Exceptionally High Incidence of Grade 2-3 Late Rectal Toxicity in Patients with Prostate Cancer Receiving Hypofractionated (2.2 Gy) Soft Tissue-matched Image-guided Intensity-modulated Radiotherapy (original) (raw)
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Strahlentherapie und Onkologie, 2006
Purpose: To compare late rectal toxicity rates after three-dimensional conformal radiotherapy to the prostate alone (P-3D-CRT) and whole-pelvis intensity-modulated radiotherapy along with a prostate boost (WP-IMRT/PB) to the same nominal total dose to the prostate. Patients and Methods: 68 patients treated with conformal radiotherapy to the prostate only to 76 Gy at the National Institute for Cancer Research, Genoa, Italy, represented the first group (P-3D-CRT). The second group consisted of 45 patients treated at the University of Texas Medical Branch (UTMB), Galveston, TX, USA, with IMRT covering the pelvic nodes and seminal vesicles to 54 Gy at 1.8 Gy per fraction and the prostate to 60 Gy in the same 30 fractions. A separate phase boosted the prostate to 76 Gy (WP-IMRT/PB). Major aspects of planning were remarkably similar at both institutions leaving the inclusion or not of pelvic nodes as the main treatment-related difference between the two groups. Late rectal toxicity was prospectively scored according to the RTOG scale. All patients have a 12-month minimum follow-up, and mean follow-up, similar in both groups, is 25.9 months (SD [standard deviation]: 8.4 months). Results: At 2 years, the estimated cumulative incidence of grade 2 late rectal toxicity is 6% ± 4% for WP-IMRT/PB and 21.2% ± 6% for P-3D-CRT (p = 0.06). The difference became significant (HR [hazard ratio] = 0.1, 95% CI [confidence interval]: 0.0-0.6; p = 0.01) at multivariate analysis. None of the patients developed grade 3+ toxicity. Conclusion: Despite the larger treated volume, WP-IMRT/PB allows more rectal sparing than P-3D-CRT.
Rectal dose reduction with IMRT for prostate radiotherapy.
Dose escalation in radiation therapy has led to increased control rates with some clinical trial evidence that rectal toxicity may be reduced when using intensity-modulated radiotherapy (IMRT) over 3D conformal radiotherapy (3DCRT) for dose-escalated prostate radiotherapy. However, IMRT for prostate patients is not yet standard in many Australian radiation oncology centres. This study investigates dosimetric changes that can be observed between IMRT and 3DCRT in prostate radiotherapy. Fifteen patients were selected for analysis. Two target definitions were investigated – prostate-only and prostate plus seminal vesicles (p + SVs). A five-field 3DCRT and seven field IMRT plan were created for each patient and target definition. The planning target volume coverage was matched for both plans. Doses to the rectum, bladder and femoral heads were compared using dose volume histograms. The rectal normal tissue complication probabilities (NTCPs) were calculated and compared for the 3DCRT and IMRT plans. The delivery efficiency was investigated. The IMRT plans resulted in reductions in the V25, V50, V60, V70 and V75 Gy values for both the prostate-only and p + SVs targets. Rectal NTCP was reduced with IMRT for three different sets of model parameters. The reductions in rectal dose and NTCP were much larger for the p + SVs target. Delivery of IMRT plans was less efficient than for 3DCRT plans. IMRT resulted in superior plans based on dosimetric and biological endpoints. The dosimetric gains with IMRT were greater for the more complex p + SVs target. The gains made came at the cost of decreased delivery efficiency.
Radiation Oncology, 2014
Background: Image-guided radiotherapy (IGRT) facilitates the delivery of a very precise radiation dose. In this study we compare the toxicity and biochemical progression-free survival between patients treated with daily imageguided intensity-modulated radiotherapy (IG-IMRT) and 3D conformal radiotherapy (3DCRT) without daily image guidance for high risk prostate cancer (PCa). Methods: A total of 503 high risk PCa patients treated with radiotherapy (RT) and endocrine treatment between 2000 and 2010 were retrospectively reviewed. 115 patients were treated with 3DCRT, and 388 patients were treated with IG-IMRT. 3DCRT patients were treated to 76 Gy and without daily image guidance and with 1-2 cm PTV margins. IG-IMRT patients were treated to 78 Gy based on daily image guidance of fiducial markers, and the PTV margins were 5-7 mm. Furthermore, the dose-volume constraints to both the rectum and bladder were changed with the introduction of IG-IMRT. Results: The 2-year actuarial likelihood of developing grade > = 2 GI toxicity following RT was 57.3% in 3DCRT patients and 5.8% in IG-IMRT patients (p < 0.001). For GU toxicity the numbers were 41.8% and 29.7%, respectively (p = 0.011). On multivariate analysis, 3DCRT was associated with a significantly increased risk of developing grade > = 2 GI toxicity compared to IG-IMRT (p < 0.001, HR = 11.59 [CI: 6.67-20.14]). 3DCRT was also associated with an increased risk of developing GU toxicity compared to IG-IMRT. The 3-year actuarial biochemical progression-free survival probability was 86.0% for 3DCRT and 90.3% for IG-IMRT (p = 0.386). On multivariate analysis there was no difference in biochemical progression-free survival between 3DCRT and IG-IMRT. Conclusion: The difference in toxicity can be attributed to the combination of the IMRT technique with reduced dose to organs-at-risk, daily image guidance and margin reduction.
Radiation oncology (London, England), 2016
To determine whether dose/volume specific endpoints (DVSE) or Area under the rectal DVH curve (rAUC) better predict acute gastrointestinal (GI) toxicity in prostate cancer patients treated with IMRT in the era of daily image guidance (IG-IMRT). A set of DVSE was recorded from V25 to V75 (increments of 5Gy) (both in % and in cc) for 180 men. The rAUC was calculated for doses ranging between 25Gy and 50Gy (rAUC25-50). Univariate and multivariate logistic regressions were performed to determine the relationship between DVSE or rAUC25-50 and the appearance of any acute GI toxicity. The rates of acute grade 1 (G1), G2 and G3 GI toxicities were 53.3 %, 10.6 % and 1.1 %, respectively. No G4+ toxicity was observed. Rectal V25 to V75 expressed in % were not predictive of G ≥ 1 GI toxicity (p ≥ 0.12) whereas rectal V25 to V50 expressed in cc did correlate with GI toxicity G ≥ 1 (p ≤ 0.04). rAUC25-50 expressed in cc. Gy correlated significantly with the occurrence of any acute GI toxicity G ≥ ...
Urologic Oncology: Seminars and Original Investigations, 2004
Purpose: When Ͼ25% of the rectum is irradiated to Ն70 Gy, the risk of developing Grade 2 or higher rectal complications is significantly increased. This study evaluates the impact on dose to the rectum from the use of an intrarectal (IR) balloon device, previously shown to immobilize the prostate gland and localize the rectum, in patients receiving dose escalated 3-dimentional (3D) conformal radiation therapy. Materials and Methods: From July 2001 through February 2003, 28 consecutive patients with prostate cancer underwent computerized tomography-based simulation with and without the IR balloon in place. Treatment planning was performed for three clinical paradigms in which the IR balloon was not used at all (0 Gy), used during the cone-down for 15 treatments (28.35 Gy), or used for the entire course of 40 treatments (75.6 Gy). The three plans were compared for differences in the percent of rectum receiving Ͼ70 Gy. Results: Dose volume histogram (DVH) analysis revealed that the median(range) of percent rectal volume exceeding 70 Gy was 25% (12.7-41.5%), 7.5% (0.9 -19.5%), and 3.6% (0 -8.7%) for patients in whom the IR balloon was used for 0, 15, and 40 treatments, respectively. The percent of rectum exceeding 70 Gy was significantly different for all treatment plan comparisons (P Ͻ 0.0001). Conclusions: Grade 2 or higher rectal toxicity may be minimized during dose escalated 3D conformal radiation therapy through the use of an IR balloon during the 3-week cone down portion of an 8-week treatment course.
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, 2014
To define rectal dose volume constraints (DVC) to prevent ⩾grade2 late rectal toxicity (LRT) after intensity modulated radiotherapy (IMRT) for prostate cancer (PC). Six hundred thirty-seven PC patients were treated with primary (prostate median dose: 78Gy) or postoperative (prostatic bed median dose: 74Gy (adjuvant)-76Gy (salvage)) IMRTwhile restricting the rectal dose to 76Gy, 72Gy and 74Gy respectively. The impact of patient characteristics and rectal volume parameters on ⩾grade2 LRT was determined. DVC were defined to estimate the 5% and 10% risk of developing ⩾grade2 LRT. The 5-year probability of being free from ⩾grade2 LRT, non-rectal blood loss and persisting symptoms is 88.8% (95% CI: 85.8-91.1%), 93.4% (95% CI: 91.0-95.1%) and 94.3% (95% CI: 92.0-95.9%) respectively. There was no correlation with patient characteristics. All volume parameters, except rectal volume receiving ⩾70Gy (R70), were significantly correlated with ⩾grade2 LRT. To avoid 10% and 5% risk of ⩾grade2 LRT ...
Rectal dose variation during the course of image-guided radiation therapy of prostate cancer
Radiotherapy and Oncology, 2010
Background and purpose: To investigate the change in rectal dose during the treatment course for intensity-modulated radiotherapy (IMRT) of prostate cancer with image-guidance. Materials and methods: Twenty prostate cancer patients were recruited for this retrospective study. All patients have been treated with IMRT. For each patient, MR and CT images were fused for target and critical structure delineation. IMRT treatment planning was performed on the simulation CT images. Interfractional motion during the course of treatment was corrected using a CT-on-rails system. The rectum was outlined on both the original treatment plan and the subsequent daily CT images from the CT-onrails by the same investigator. Dose distributions on these daily CT images were recalculated with the isocenter shifts relative to the simulation CT images using the leaf sequences/MUs based on the original treatment plan. The rectal doses from the subsequent daily CTs were compared with the original doses planned on the simulation CT using our clinical acceptance criteria. Results: Based on 20 patients with 139 daily CT sets, 28% of the subsequent treatment dose distributions did not meet our criterion of V 40 < 35%, and 27% did not meet our criterion of V 65 < 17%. The inter-fractional rectal volume variation is significant for some patients. Conclusions: Due to the large inter-fractional variation of the rectal volume, it is more favorable to plan prostate IMRT based on an empty rectum and deliver treatment to patients with an empty rectum. Over 70% of actual treatments showed better rectal doses than our clinical acceptance criteria. A significant fraction (27%) of the actual treatments would benefit from adaptive image-guided radiotherapy based on daily CT images.