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Papers by Christian Ekanger

Research paper thumbnail of Salvage Reirradiation for Locally Recurrent Prostate Cancer: Results From a Prospective Study With 7.2 Years of Follow-Up

Journal of clinical oncology, Apr 23, 2024

Research paper thumbnail of IMRT pelvic radiotherapy with simultaneous integrated boost in high-risk prostate cancer: Results after 10 years

Journal of Clinical Oncology, May 20, 2019

5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (I... more 5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (IMRT) with hypofractionated simultaneous integrated boost (SIB) in high-risk prostate cancer. Methods: Between 2007 and 2009, 97 patients with an estimated risk of lymph node metastases above 15% (Roach equation) were prospectively included in a phase II study. Patients were treated with 2-2.7 Gy to the prostate, vesicula seminalis and elective pelvic field in 25 fractions over 5 weeks with androgen deprivation therapy for 2 years. Toxicity was scored according to RTOG criteria and biochemical free survival (BFS) using the Phoenix definition. Patients were divided into three groups; very high-risk patients (VHR) according to NCCN 2015 criteria (n=50), high-risk patients (HR) (n=32), and patients with N+ disease and/or pretreatment s-PSA ≥100 (n=15). Differences were examined using Kaplan Meier estimates with log rank test. Results: Ten year BFS in the entire cohort was 63%. Metastasis-free survival (MFS) was 77% and prostate-cancer-specific-survival (PCSS) 88%. Overall survival (OS) was 69% and local failure rate was 11%. VHR vs. HR subgroups had significant different BFS; 58% vs 84% (p=0.01) respectively. MFS and PCSS in the VHR group compared to the HR group was 78% vs 91% (p=0.108) and 86% vs 97% (p=0.157) respectively. Patients with N+ and/or PSA>100 had worse outcome compared to the HR/VHR groups, but not all had treatment failure. BFS was 33% vs 68% (p=0.001), MFS 47% vs 83% (p=0.000) and PCSS 73 % vs 90% (p=0.04), respectively. Patients who reached a PSA nadir value below 0.1 (n=80) had significant better outcomes, with PCSS 93% vs 65% (p= 0.001) and BFS 74% vs 12% (p=0.000), respectively. Acute gr 2 GI and GU toxicity was observed in 27% and 40%, gr 3 GI and GU toxicity in 1% and 3%. Late gr 2 GI and GU toxicity at 3 years appeared in 3% and 4% with no gr 3 toxicity. Conclusions: High-risk prostate cancer patients treated with IMRT with SIB obtained favorable outcomes with few serious side effects. There were significant better results in the HR versus the VHR group, both better than the N+/PSA≥100 group.

Research paper thumbnail of PD-0165 Combining patient and population rectal shapes for re-irradiation of recurring prostate cancer

Radiotherapy and Oncology, May 1, 2023

Research paper thumbnail of Prediction of rectum and bladder morbidity following radiotherapy of prostate cancer based on motion-inclusive dose distributions

Radiotherapy and Oncology, May 1, 2013

Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the ... more Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the rectum and the bladder-display considerable motion, which may influence the dose/volume parameters predicting for morbidity. In this study we compare motion-inclusive doses to planned doses for the rectum and bladder and explore their associations with prospectively recorded morbidity. Materials and methods: The study included 38 prostate cancer patients treated with hypo-fractionated image-guided intensity-modulated RT that had an average of nine repeat CT scans acquired during treatment. These scans were registered to the respective treatment planning CT (pCT) followed by a new dose calculation from which motion-inclusive dose distributions were derived. The pCT volumes, the treatment course averaged volumes as well as the planned and motion-inclusive doses were associated with acute and late morbidity (morbidity cutoff: PGrade 2). Results: Acute rectal morbidity (observed in 29% of cases) was significantly associated with both smaller treatment course averaged rectal volumes (population median: 75 vs. 94 cm 3) and the motion-inclusive volume receiving doses close to the prescription dose (2 Gy-equivalent dose of 76 Gy). Conclusion: Variation in rectum and bladder volumes leads to deviations between planned and delivered dose/volume parameters that should be accounted for to improve the ability to predict morbidity following RT.

Research paper thumbnail of Statistical motion modelling for robust evaluation of clinically delivered accumulated dose distributions after curative radiotherapy of locally advanced prostate cancer

Radiotherapy and Oncology, Aug 1, 2018

Planned doses are used as surrogate for the actually delivered dose in radiotherapy. We have esti... more Planned doses are used as surrogate for the actually delivered dose in radiotherapy. We have estimated the delivered dose in a dose-escalation trial of locally advanced prostate cancer by statistical dose-accumulation and by DVH-summation, and compared to planned dose. Materials and method: Prescribed dose-escalation to the prostate was 67.5 Gy/25fr., corresponding to 81GyEQD2 assuming a/b = 1.5. The 21 patients had three targets (i.e. CTV67.5 + 2 mm, CTV60 + 5 mm, CTV50 + 10 mm) irradiated by a simultaneous-integrated-boost technique. Analysis was based on 213 CT scans and 5-years of follow-up. For statistical dose-accumulation, we modelled 10 000 possible treatment courses based on planned dose and deformation-vector-fields from contour-based registration. For DVH-summation we recalculated dose on repeat-CTs and estimated median D98%/EUD. Groups with/without disease recurrence were compared. Results: Discrepancies between planned and accumulated dose were mostly seen for CTV67.5, where under-dosage was found at different locations in the prostate in 12/21 patients. Delivered doseescalation (D98%) was on average 73.9GyEQD2 (range: 68.3-78.7GyEQD2). No significant difference in accumulated-D98% was found in patients with (n = 8) and without (n = 13) recurrence (p > 0.05). Average D98%/EUD with statistical dose-accumulation vs DVH-summation was significantly different in CTV60, CTV50, rectum and bladder but not in CTV67.5. Conclusion: The planned dose escalation was not received by more than half-of-the patients. Robustness of the prostate target (CTV67.5) should therefore be better prioritized in these patients given the low toxicity profile. Estimates of delivered dose were less conservative for dose-accumulation due to interaction of random organ motion with the dose matrix.

Research paper thumbnail of Risk of radiation-induced secondary rectal and bladder cancer following radiotherapy of prostate cancer

Acta Oncologica, Jul 31, 2015

Research paper thumbnail of PO-0912: The risk of radiation-induced cancer following VMAT vs. IMPT of prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of OC-0400: Dosimetric consequences of organ deformations in IMRT of locally advanced prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of Impact of positive surgical margins on secondary treatment, palliative radiotherapy and prostate cancer‐specific mortality. A population‐based study of 13 198 patients

The Prostate, Sep 30, 2019

Background: The results of studies evaluating the impact of positive surgical margins on prostate... more Background: The results of studies evaluating the impact of positive surgical margins on prostate cancer-specific mortality have been inconsistent. We, therefore, evaluated the impact of surgical margin status on subsequent secondary treatment, palliative radiotherapy, and prostate cancer-specific mortality. Methods: A total of 14 837 men treated with radical prostatectomy (RP) during the period 2001 to 2015 were identified from the Cancer Registry of Norway. Of those, 13 198 (89%) patients had complete data on the preoperative prostate-specific antigen level, pathological T-category, Gleason score in the prostatectomy specimen, and margin status. Multivariable Cox proportional hazards models were used to evaluate the risk, and flexible parametric models for the cumulative incidence were fitted to predict the probabilities of secondary treatment (salvage radiotherapy or prophylactic breast radiation), palliative radiotherapy, and prostate cancer-specific mortality. Results: After a median follow-up time of 5.2 years (3591 patients with ≥8 years of follow-up), positive surgical margins (PSMs) were independently predictive of secondary treatment (hazard ratio [HR] = 2.43, 95% confidence interval [CI] = 2.21-2.66) and palliative radiotherapy (HR = 1.45, 95% CI = 1.03-2.05). After 10 years, the absolute increased risk for palliative radiotherapy in patients with PSMs after RP varied between 0.1% in pT2 tumors with a Gleason score of 6, to 12% for pT3b tumors with a Gleason score of 9 to 10. PSMs were not independently associated with prostate cancer-specific mortality (HR = 1.14, 95% CI = 0.82-1.59). Conclusion: PSMs were associated with increased application of secondary treatment and palliative radiotherapy but were not predictive of prostate cancer-specific mortality. As the use of palliative radiotherapy was only marginally increased in

Research paper thumbnail of PO-0861: Prediction of normal tissue morbidity in radiotherapy of prostate cancer using motion inclusive dose distributions

Radiotherapy and Oncology, Mar 1, 2013

In the lower graph (Fig. 1C), we can observe an increase in ΔADC as dose increases, although the ... more In the lower graph (Fig. 1C), we can observe an increase in ΔADC as dose increases, although the data are not relevant enough because of the few number of patients analyzed. Conclusions: ADC maps can be used not only for treatment assessment, but also for quantification of tumour response voxel by voxel. Even more, the joint use of MRI diffusion data and PET/CT can be useful for delimiting the hypoxic areas, due to glucose consumption enhancement by Pasteur effect. The main weakness of this method is the rigid registration process, and non rigid registration algorithms are needed for the registration of highly distorted images from diffusion studies.

Research paper thumbnail of Prediction of rectum and bladder morbidity following radiotherapy of prostate cancer based on motion-inclusive dose distributions

Radiotherapy and Oncology, 2013

Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the ... more Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the rectum and the bladder-display considerable motion, which may influence the dose/volume parameters predicting for morbidity. In this study we compare motion-inclusive doses to planned doses for the rectum and bladder and explore their associations with prospectively recorded morbidity. Materials and methods: The study included 38 prostate cancer patients treated with hypo-fractionated image-guided intensity-modulated RT that had an average of nine repeat CT scans acquired during treatment. These scans were registered to the respective treatment planning CT (pCT) followed by a new dose calculation from which motion-inclusive dose distributions were derived. The pCT volumes, the treatment course averaged volumes as well as the planned and motion-inclusive doses were associated with acute and late morbidity (morbidity cutoff: PGrade 2). Results: Acute rectal morbidity (observed in 29% of cases) was significantly associated with both smaller treatment course averaged rectal volumes (population median: 75 vs. 94 cm 3) and the motion-inclusive volume receiving doses close to the prescription dose (2 Gy-equivalent dose of 76 Gy). Conclusion: Variation in rectum and bladder volumes leads to deviations between planned and delivered dose/volume parameters that should be accounted for to improve the ability to predict morbidity following RT.

Research paper thumbnail of PD-0297: Estimating the probability of active tumor in cervical cancer derived from PET/MR-imaging

Radiotherapy and Oncology, 2020

Research paper thumbnail of PO-0912: The risk of radiation-induced cancer following VMAT vs. IMPT of prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of OC-0400: Dosimetric consequences of organ deformations in IMRT of locally advanced prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of Ten years results from a phase II study on image guided Intensity–Modulated Radiation Therapy with simultaneous integrated boost in high-risk prostate cancer

Advances in Radiation Oncology

There is no consensus on how to treat high-risk prostate cancer, and long-term results from hypof... more There is no consensus on how to treat high-risk prostate cancer, and long-term results from hypofractionated radiation therapy are lacking. We report 10-year results after image guided, intensity modulated radiation therapy with hypofractionated simultaneous integrated boost and elective pelvic field. Methods and Materials: Between 2007 and 2009, 97 consecutive patients with high-risk prostate cancer were included, treated with 2.7 to 2.0 Gy  25 Gy to the prostate, seminal vesicles, and elective pelvic field. Toxicity was scored according to Radiation Therapy Oncology Group criteria and biochemical disease-free survival (BFS) defined by the Phoenix definition. Patients were subsequently divided into 3 groups: high risk (HR; n Z 32), very high risk (VHR; n Z 50), and Nþ/seprostate-specific antigen (PSA) !100 (n Z 15). Differences in outcomes were examined using Kaplan-Meier analyses. Results: BFS in the patients at HR and VHR was 64%, metastasis-free survival 80%, prostate cancer-specific survival 90%, and overall survival (OS) 72%. VHR versus HR subgroups demonstrated significantly different BFS, 54% versus 79% (P Z .01). Metastasis-free survival and prostate cancer-specific survival in the VHR group versus HR group were 76% versus 87% (P Z .108) and 74% versus

Research paper thumbnail of PO-0861: Prediction of normal tissue morbidity in radiotherapy of prostate cancer using motion inclusive dose distributions

Radiotherapy and Oncology, 2013

Research paper thumbnail of Clinical iterative model development improves knowledge-based plan quality for high-risk prostate cancer with four integrated dose levels

Acta Oncologica

Background: Manual volumetric modulated arc therapy (VMAT) treatment planning for high-risk prost... more Background: Manual volumetric modulated arc therapy (VMAT) treatment planning for high-risk prostate cancer receiving whole pelvic radiotherapy (WPRT) with four integrated dose levels is complex and time consuming. We have investigated if the radiotherapy planning process and plan quality can be improved using a well-tuned model developed through a commercial system for knowledge-based planning (KBP). Material and methods: Treatment plans from 69 patients treated for high-risk prostate cancer with manually planned VMAT were used to develop an initial KBP model (RapidPlan, RP). Prescribed doses were 50, 60, 67.5, and 72.5 Gy in 25 fractions to the pelvic lymph nodes, prostate and seminal vesicles, prostate gland, and prostate tumour(s), respectively. This RP model was in clinical use from July 2019 to February 2020, producing another set of 69 clinically delivered treatment plans for a new patient group, which were used to develop a second RP model. Both models were validated on an independent group of 40 patients. Plan quality was compared by D 98% and the Paddick conformity index for targets, mean dose (D mean) and generalised equivalent uniform dose (gEUD) for bladder, bowel bag and rectum, and number of monitor units (MU). Results: Target coverage and conformity was similar between manually created and RP treatment plans. Compared to the manually created treatment plans, the final RP model reduced average D mean and gEUD with 2.7 Gy and 1.3 Gy for bladder, 1.2 Gy and 0.9 Gy for bowel bag, and 2.7 Gy and 0.8 Gy for rectum, respectively (p < .05). For rectum, the interpatient variation (i.e., 95% confidence interval) of DVHs was reduced by 23%. Conclusion: KBP improved plan quality and consistency among treatment plans for high-risk prostate cancer. Model tuning using KBP-based clinical plans further improved model outcome.

Research paper thumbnail of Impact of positive surgical margins on secondary treatment, palliative radiotherapy and prostate cancer‐specific mortality. A population‐based study of 13 198 patients

The Prostate

Background: The results of studies evaluating the impact of positive surgical margins on prostate... more Background: The results of studies evaluating the impact of positive surgical margins on prostate cancer-specific mortality have been inconsistent. We, therefore, evaluated the impact of surgical margin status on subsequent secondary treatment, palliative radiotherapy, and prostate cancer-specific mortality. Methods: A total of 14 837 men treated with radical prostatectomy (RP) during the period 2001 to 2015 were identified from the Cancer Registry of Norway. Of those, 13 198 (89%) patients had complete data on the preoperative prostate-specific antigen level, pathological T-category, Gleason score in the prostatectomy specimen, and margin status. Multivariable Cox proportional hazards models were used to evaluate the risk, and flexible parametric models for the cumulative incidence were fitted to predict the probabilities of secondary treatment (salvage radiotherapy or prophylactic breast radiation), palliative radiotherapy, and prostate cancer-specific mortality. Results: After a median follow-up time of 5.2 years (3591 patients with ≥8 years of follow-up), positive surgical margins (PSMs) were independently predictive of secondary treatment (hazard ratio [HR] = 2.43, 95% confidence interval [CI] = 2.21-2.66) and palliative radiotherapy (HR = 1.45, 95% CI = 1.03-2.05). After 10 years, the absolute increased risk for palliative radiotherapy in patients with PSMs after RP varied between 0.1% in pT2 tumors with a Gleason score of 6, to 12% for pT3b tumors with a Gleason score of 9 to 10. PSMs were not independently associated with prostate cancer-specific mortality (HR = 1.14, 95% CI = 0.82-1.59). Conclusion: PSMs were associated with increased application of secondary treatment and palliative radiotherapy but were not predictive of prostate cancer-specific mortality. As the use of palliative radiotherapy was only marginally increased in

Research paper thumbnail of IMRT pelvic radiotherapy with simultaneous integrated boost in high-risk prostate cancer: Results after 10 years

Journal of Clinical Oncology

5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (I... more 5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (IMRT) with hypofractionated simultaneous integrated boost (SIB) in high-risk prostate cancer. Methods: Between 2007 and 2009, 97 patients with an estimated risk of lymph node metastases above 15% (Roach equation) were prospectively included in a phase II study. Patients were treated with 2-2.7 Gy to the prostate, vesicula seminalis and elective pelvic field in 25 fractions over 5 weeks with androgen deprivation therapy for 2 years. Toxicity was scored according to RTOG criteria and biochemical free survival (BFS) using the Phoenix definition. Patients were divided into three groups; very high-risk patients (VHR) according to NCCN 2015 criteria (n=50), high-risk patients (HR) (n=32), and patients with N+ disease and/or pretreatment s-PSA ≥100 (n=15). Differences were examined using Kaplan Meier estimates with log rank test. Results: Ten year BFS in the entire cohort was 63%. Metastasis-fre...

Research paper thumbnail of Statistical motion modelling for robust evaluation of clinically delivered accumulated dose distributions after curative radiotherapy of locally advanced prostate cancer

Radiotherapy and Oncology

Research paper thumbnail of Salvage Reirradiation for Locally Recurrent Prostate Cancer: Results From a Prospective Study With 7.2 Years of Follow-Up

Journal of clinical oncology, Apr 23, 2024

Research paper thumbnail of IMRT pelvic radiotherapy with simultaneous integrated boost in high-risk prostate cancer: Results after 10 years

Journal of Clinical Oncology, May 20, 2019

5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (I... more 5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (IMRT) with hypofractionated simultaneous integrated boost (SIB) in high-risk prostate cancer. Methods: Between 2007 and 2009, 97 patients with an estimated risk of lymph node metastases above 15% (Roach equation) were prospectively included in a phase II study. Patients were treated with 2-2.7 Gy to the prostate, vesicula seminalis and elective pelvic field in 25 fractions over 5 weeks with androgen deprivation therapy for 2 years. Toxicity was scored according to RTOG criteria and biochemical free survival (BFS) using the Phoenix definition. Patients were divided into three groups; very high-risk patients (VHR) according to NCCN 2015 criteria (n=50), high-risk patients (HR) (n=32), and patients with N+ disease and/or pretreatment s-PSA ≥100 (n=15). Differences were examined using Kaplan Meier estimates with log rank test. Results: Ten year BFS in the entire cohort was 63%. Metastasis-free survival (MFS) was 77% and prostate-cancer-specific-survival (PCSS) 88%. Overall survival (OS) was 69% and local failure rate was 11%. VHR vs. HR subgroups had significant different BFS; 58% vs 84% (p=0.01) respectively. MFS and PCSS in the VHR group compared to the HR group was 78% vs 91% (p=0.108) and 86% vs 97% (p=0.157) respectively. Patients with N+ and/or PSA&amp;amp;amp;amp;amp;amp;amp;gt;100 had worse outcome compared to the HR/VHR groups, but not all had treatment failure. BFS was 33% vs 68% (p=0.001), MFS 47% vs 83% (p=0.000) and PCSS 73 % vs 90% (p=0.04), respectively. Patients who reached a PSA nadir value below 0.1 (n=80) had significant better outcomes, with PCSS 93% vs 65% (p= 0.001) and BFS 74% vs 12% (p=0.000), respectively. Acute gr 2 GI and GU toxicity was observed in 27% and 40%, gr 3 GI and GU toxicity in 1% and 3%. Late gr 2 GI and GU toxicity at 3 years appeared in 3% and 4% with no gr 3 toxicity. Conclusions: High-risk prostate cancer patients treated with IMRT with SIB obtained favorable outcomes with few serious side effects. There were significant better results in the HR versus the VHR group, both better than the N+/PSA≥100 group.

Research paper thumbnail of PD-0165 Combining patient and population rectal shapes for re-irradiation of recurring prostate cancer

Radiotherapy and Oncology, May 1, 2023

Research paper thumbnail of Prediction of rectum and bladder morbidity following radiotherapy of prostate cancer based on motion-inclusive dose distributions

Radiotherapy and Oncology, May 1, 2013

Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the ... more Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the rectum and the bladder-display considerable motion, which may influence the dose/volume parameters predicting for morbidity. In this study we compare motion-inclusive doses to planned doses for the rectum and bladder and explore their associations with prospectively recorded morbidity. Materials and methods: The study included 38 prostate cancer patients treated with hypo-fractionated image-guided intensity-modulated RT that had an average of nine repeat CT scans acquired during treatment. These scans were registered to the respective treatment planning CT (pCT) followed by a new dose calculation from which motion-inclusive dose distributions were derived. The pCT volumes, the treatment course averaged volumes as well as the planned and motion-inclusive doses were associated with acute and late morbidity (morbidity cutoff: PGrade 2). Results: Acute rectal morbidity (observed in 29% of cases) was significantly associated with both smaller treatment course averaged rectal volumes (population median: 75 vs. 94 cm 3) and the motion-inclusive volume receiving doses close to the prescription dose (2 Gy-equivalent dose of 76 Gy). Conclusion: Variation in rectum and bladder volumes leads to deviations between planned and delivered dose/volume parameters that should be accounted for to improve the ability to predict morbidity following RT.

Research paper thumbnail of Statistical motion modelling for robust evaluation of clinically delivered accumulated dose distributions after curative radiotherapy of locally advanced prostate cancer

Radiotherapy and Oncology, Aug 1, 2018

Planned doses are used as surrogate for the actually delivered dose in radiotherapy. We have esti... more Planned doses are used as surrogate for the actually delivered dose in radiotherapy. We have estimated the delivered dose in a dose-escalation trial of locally advanced prostate cancer by statistical dose-accumulation and by DVH-summation, and compared to planned dose. Materials and method: Prescribed dose-escalation to the prostate was 67.5 Gy/25fr., corresponding to 81GyEQD2 assuming a/b = 1.5. The 21 patients had three targets (i.e. CTV67.5 + 2 mm, CTV60 + 5 mm, CTV50 + 10 mm) irradiated by a simultaneous-integrated-boost technique. Analysis was based on 213 CT scans and 5-years of follow-up. For statistical dose-accumulation, we modelled 10 000 possible treatment courses based on planned dose and deformation-vector-fields from contour-based registration. For DVH-summation we recalculated dose on repeat-CTs and estimated median D98%/EUD. Groups with/without disease recurrence were compared. Results: Discrepancies between planned and accumulated dose were mostly seen for CTV67.5, where under-dosage was found at different locations in the prostate in 12/21 patients. Delivered doseescalation (D98%) was on average 73.9GyEQD2 (range: 68.3-78.7GyEQD2). No significant difference in accumulated-D98% was found in patients with (n = 8) and without (n = 13) recurrence (p > 0.05). Average D98%/EUD with statistical dose-accumulation vs DVH-summation was significantly different in CTV60, CTV50, rectum and bladder but not in CTV67.5. Conclusion: The planned dose escalation was not received by more than half-of-the patients. Robustness of the prostate target (CTV67.5) should therefore be better prioritized in these patients given the low toxicity profile. Estimates of delivered dose were less conservative for dose-accumulation due to interaction of random organ motion with the dose matrix.

Research paper thumbnail of Risk of radiation-induced secondary rectal and bladder cancer following radiotherapy of prostate cancer

Acta Oncologica, Jul 31, 2015

Research paper thumbnail of PO-0912: The risk of radiation-induced cancer following VMAT vs. IMPT of prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of OC-0400: Dosimetric consequences of organ deformations in IMRT of locally advanced prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of Impact of positive surgical margins on secondary treatment, palliative radiotherapy and prostate cancer‐specific mortality. A population‐based study of 13 198 patients

The Prostate, Sep 30, 2019

Background: The results of studies evaluating the impact of positive surgical margins on prostate... more Background: The results of studies evaluating the impact of positive surgical margins on prostate cancer-specific mortality have been inconsistent. We, therefore, evaluated the impact of surgical margin status on subsequent secondary treatment, palliative radiotherapy, and prostate cancer-specific mortality. Methods: A total of 14 837 men treated with radical prostatectomy (RP) during the period 2001 to 2015 were identified from the Cancer Registry of Norway. Of those, 13 198 (89%) patients had complete data on the preoperative prostate-specific antigen level, pathological T-category, Gleason score in the prostatectomy specimen, and margin status. Multivariable Cox proportional hazards models were used to evaluate the risk, and flexible parametric models for the cumulative incidence were fitted to predict the probabilities of secondary treatment (salvage radiotherapy or prophylactic breast radiation), palliative radiotherapy, and prostate cancer-specific mortality. Results: After a median follow-up time of 5.2 years (3591 patients with ≥8 years of follow-up), positive surgical margins (PSMs) were independently predictive of secondary treatment (hazard ratio [HR] = 2.43, 95% confidence interval [CI] = 2.21-2.66) and palliative radiotherapy (HR = 1.45, 95% CI = 1.03-2.05). After 10 years, the absolute increased risk for palliative radiotherapy in patients with PSMs after RP varied between 0.1% in pT2 tumors with a Gleason score of 6, to 12% for pT3b tumors with a Gleason score of 9 to 10. PSMs were not independently associated with prostate cancer-specific mortality (HR = 1.14, 95% CI = 0.82-1.59). Conclusion: PSMs were associated with increased application of secondary treatment and palliative radiotherapy but were not predictive of prostate cancer-specific mortality. As the use of palliative radiotherapy was only marginally increased in

Research paper thumbnail of PO-0861: Prediction of normal tissue morbidity in radiotherapy of prostate cancer using motion inclusive dose distributions

Radiotherapy and Oncology, Mar 1, 2013

In the lower graph (Fig. 1C), we can observe an increase in ΔADC as dose increases, although the ... more In the lower graph (Fig. 1C), we can observe an increase in ΔADC as dose increases, although the data are not relevant enough because of the few number of patients analyzed. Conclusions: ADC maps can be used not only for treatment assessment, but also for quantification of tumour response voxel by voxel. Even more, the joint use of MRI diffusion data and PET/CT can be useful for delimiting the hypoxic areas, due to glucose consumption enhancement by Pasteur effect. The main weakness of this method is the rigid registration process, and non rigid registration algorithms are needed for the registration of highly distorted images from diffusion studies.

Research paper thumbnail of Prediction of rectum and bladder morbidity following radiotherapy of prostate cancer based on motion-inclusive dose distributions

Radiotherapy and Oncology, 2013

Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the ... more Background and purpose: In radiotherapy (RT) of prostate cancer the key organs at risk (ORs)-the rectum and the bladder-display considerable motion, which may influence the dose/volume parameters predicting for morbidity. In this study we compare motion-inclusive doses to planned doses for the rectum and bladder and explore their associations with prospectively recorded morbidity. Materials and methods: The study included 38 prostate cancer patients treated with hypo-fractionated image-guided intensity-modulated RT that had an average of nine repeat CT scans acquired during treatment. These scans were registered to the respective treatment planning CT (pCT) followed by a new dose calculation from which motion-inclusive dose distributions were derived. The pCT volumes, the treatment course averaged volumes as well as the planned and motion-inclusive doses were associated with acute and late morbidity (morbidity cutoff: PGrade 2). Results: Acute rectal morbidity (observed in 29% of cases) was significantly associated with both smaller treatment course averaged rectal volumes (population median: 75 vs. 94 cm 3) and the motion-inclusive volume receiving doses close to the prescription dose (2 Gy-equivalent dose of 76 Gy). Conclusion: Variation in rectum and bladder volumes leads to deviations between planned and delivered dose/volume parameters that should be accounted for to improve the ability to predict morbidity following RT.

Research paper thumbnail of PD-0297: Estimating the probability of active tumor in cervical cancer derived from PET/MR-imaging

Radiotherapy and Oncology, 2020

Research paper thumbnail of PO-0912: The risk of radiation-induced cancer following VMAT vs. IMPT of prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of OC-0400: Dosimetric consequences of organ deformations in IMRT of locally advanced prostate cancer

Radiotherapy and Oncology, Apr 1, 2015

Research paper thumbnail of Ten years results from a phase II study on image guided Intensity–Modulated Radiation Therapy with simultaneous integrated boost in high-risk prostate cancer

Advances in Radiation Oncology

There is no consensus on how to treat high-risk prostate cancer, and long-term results from hypof... more There is no consensus on how to treat high-risk prostate cancer, and long-term results from hypofractionated radiation therapy are lacking. We report 10-year results after image guided, intensity modulated radiation therapy with hypofractionated simultaneous integrated boost and elective pelvic field. Methods and Materials: Between 2007 and 2009, 97 consecutive patients with high-risk prostate cancer were included, treated with 2.7 to 2.0 Gy  25 Gy to the prostate, seminal vesicles, and elective pelvic field. Toxicity was scored according to Radiation Therapy Oncology Group criteria and biochemical disease-free survival (BFS) defined by the Phoenix definition. Patients were subsequently divided into 3 groups: high risk (HR; n Z 32), very high risk (VHR; n Z 50), and Nþ/seprostate-specific antigen (PSA) !100 (n Z 15). Differences in outcomes were examined using Kaplan-Meier analyses. Results: BFS in the patients at HR and VHR was 64%, metastasis-free survival 80%, prostate cancer-specific survival 90%, and overall survival (OS) 72%. VHR versus HR subgroups demonstrated significantly different BFS, 54% versus 79% (P Z .01). Metastasis-free survival and prostate cancer-specific survival in the VHR group versus HR group were 76% versus 87% (P Z .108) and 74% versus

Research paper thumbnail of PO-0861: Prediction of normal tissue morbidity in radiotherapy of prostate cancer using motion inclusive dose distributions

Radiotherapy and Oncology, 2013

Research paper thumbnail of Clinical iterative model development improves knowledge-based plan quality for high-risk prostate cancer with four integrated dose levels

Acta Oncologica

Background: Manual volumetric modulated arc therapy (VMAT) treatment planning for high-risk prost... more Background: Manual volumetric modulated arc therapy (VMAT) treatment planning for high-risk prostate cancer receiving whole pelvic radiotherapy (WPRT) with four integrated dose levels is complex and time consuming. We have investigated if the radiotherapy planning process and plan quality can be improved using a well-tuned model developed through a commercial system for knowledge-based planning (KBP). Material and methods: Treatment plans from 69 patients treated for high-risk prostate cancer with manually planned VMAT were used to develop an initial KBP model (RapidPlan, RP). Prescribed doses were 50, 60, 67.5, and 72.5 Gy in 25 fractions to the pelvic lymph nodes, prostate and seminal vesicles, prostate gland, and prostate tumour(s), respectively. This RP model was in clinical use from July 2019 to February 2020, producing another set of 69 clinically delivered treatment plans for a new patient group, which were used to develop a second RP model. Both models were validated on an independent group of 40 patients. Plan quality was compared by D 98% and the Paddick conformity index for targets, mean dose (D mean) and generalised equivalent uniform dose (gEUD) for bladder, bowel bag and rectum, and number of monitor units (MU). Results: Target coverage and conformity was similar between manually created and RP treatment plans. Compared to the manually created treatment plans, the final RP model reduced average D mean and gEUD with 2.7 Gy and 1.3 Gy for bladder, 1.2 Gy and 0.9 Gy for bowel bag, and 2.7 Gy and 0.8 Gy for rectum, respectively (p < .05). For rectum, the interpatient variation (i.e., 95% confidence interval) of DVHs was reduced by 23%. Conclusion: KBP improved plan quality and consistency among treatment plans for high-risk prostate cancer. Model tuning using KBP-based clinical plans further improved model outcome.

Research paper thumbnail of Impact of positive surgical margins on secondary treatment, palliative radiotherapy and prostate cancer‐specific mortality. A population‐based study of 13 198 patients

The Prostate

Background: The results of studies evaluating the impact of positive surgical margins on prostate... more Background: The results of studies evaluating the impact of positive surgical margins on prostate cancer-specific mortality have been inconsistent. We, therefore, evaluated the impact of surgical margin status on subsequent secondary treatment, palliative radiotherapy, and prostate cancer-specific mortality. Methods: A total of 14 837 men treated with radical prostatectomy (RP) during the period 2001 to 2015 were identified from the Cancer Registry of Norway. Of those, 13 198 (89%) patients had complete data on the preoperative prostate-specific antigen level, pathological T-category, Gleason score in the prostatectomy specimen, and margin status. Multivariable Cox proportional hazards models were used to evaluate the risk, and flexible parametric models for the cumulative incidence were fitted to predict the probabilities of secondary treatment (salvage radiotherapy or prophylactic breast radiation), palliative radiotherapy, and prostate cancer-specific mortality. Results: After a median follow-up time of 5.2 years (3591 patients with ≥8 years of follow-up), positive surgical margins (PSMs) were independently predictive of secondary treatment (hazard ratio [HR] = 2.43, 95% confidence interval [CI] = 2.21-2.66) and palliative radiotherapy (HR = 1.45, 95% CI = 1.03-2.05). After 10 years, the absolute increased risk for palliative radiotherapy in patients with PSMs after RP varied between 0.1% in pT2 tumors with a Gleason score of 6, to 12% for pT3b tumors with a Gleason score of 9 to 10. PSMs were not independently associated with prostate cancer-specific mortality (HR = 1.14, 95% CI = 0.82-1.59). Conclusion: PSMs were associated with increased application of secondary treatment and palliative radiotherapy but were not predictive of prostate cancer-specific mortality. As the use of palliative radiotherapy was only marginally increased in

Research paper thumbnail of IMRT pelvic radiotherapy with simultaneous integrated boost in high-risk prostate cancer: Results after 10 years

Journal of Clinical Oncology

5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (I... more 5084 Background: To report 10 year results after image guided intensity-modulated radiotherapy (IMRT) with hypofractionated simultaneous integrated boost (SIB) in high-risk prostate cancer. Methods: Between 2007 and 2009, 97 patients with an estimated risk of lymph node metastases above 15% (Roach equation) were prospectively included in a phase II study. Patients were treated with 2-2.7 Gy to the prostate, vesicula seminalis and elective pelvic field in 25 fractions over 5 weeks with androgen deprivation therapy for 2 years. Toxicity was scored according to RTOG criteria and biochemical free survival (BFS) using the Phoenix definition. Patients were divided into three groups; very high-risk patients (VHR) according to NCCN 2015 criteria (n=50), high-risk patients (HR) (n=32), and patients with N+ disease and/or pretreatment s-PSA ≥100 (n=15). Differences were examined using Kaplan Meier estimates with log rank test. Results: Ten year BFS in the entire cohort was 63%. Metastasis-fre...

Research paper thumbnail of Statistical motion modelling for robust evaluation of clinically delivered accumulated dose distributions after curative radiotherapy of locally advanced prostate cancer

Radiotherapy and Oncology