Pretreatment endorectal magnetic resonance imaging and magnetic resonance spectroscopic imaging features of prostate cancer as predictors of response to external beam radiotherapy - PubMed (original) (raw)

Pretreatment endorectal magnetic resonance imaging and magnetic resonance spectroscopic imaging features of prostate cancer as predictors of response to external beam radiotherapy

Tim Joseph et al. Int J Radiat Oncol Biol Phys. 2009.

Abstract

Purpose: To evaluate whether pretreatment combined endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) findings are predictive of outcome in patients who undergo external beam radiotherapy for prostate cancer.

Methods and materials: We retrospectively identified 67 men with biopsy-proven prostate cancer who underwent combined endorectal MRI and MRSI at our institution between January 1998 and October 2003 before whole-pelvis external beam radiotherapy. A single reader recorded tumor presence, stage, and metabolic abnormality at combined MRI and MRSI. Kaplan-Meier survival and Cox univariate and multivariate analyses explored the relationship between clinical and imaging variables and outcome, using biochemical or metastatic failure as endpoints.

Results: After a mean follow-up of 44 months (range, 3-96), 6 patients developed both metastatic and biochemical failure, with an additional 13 patients developing biochemical failure alone. Multivariate Cox analysis demonstrated that the only independent predictor of biochemical failure was the volume of malignant metabolism on MRSI (hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.29-2.06; p < 0.0001). The two independent predictors of metastatic failure were MRI tumor size (HR 1.34, 95% CI 1.03-1.73; p = 0.028) and the finding of seminal vesicle invasion on MRI (HR 28.05, 95% CI 3.96-198.67; p = 0.0008).

Conclusions: In multivariate analysis, MRI and MRSI findings before EBRT in patients with prostate cancer are more accurate independent predictors of outcome than clinical variables, and in particular, the findings of seminal vesicle invasion and extensive tumor predict a worse prognosis.

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Conflict of interest statement

Conflict of interest: none.

Figures

Fig. 1

(A) Axial T2-weighted magnetic resonance imaging (MRI) section in a 68-year-old man with newly diagnosed Gleason 6 prostate cancer, serum prostate-specific antigen level of 4.6 ng/mL, and clinical stage of T2B. A large focus (arrows) of reduced T2 signal intensity is seen in the left peripheral zone of the prostate. (B) Photomontage showing the axial T2-weighted image on the left side with an overlaid grid that corresponds to the magnetic resonance spectroscopic imaging (MRSI) spectral array on the right side. The voxels that correspond to the focus of reduced T2 signal intensity show high choline peaks (arrows), consistent with prostate cancer. (C) Axial T2-weighted MRI section through the base of the prostate (at a more superior level than in panel a) shows gross extracapsular extension of tumor, with seminal vesicle invasion (Stage T3B). The patient developed metastatic recurrence 21 months after external beam radiotherapy.

Fig. 2

Graph showing the cumulative percentage of patients without metastatic recurrence of prostate cancer after external beam radiotherapy, when stratified by stage assigned by combined endorectal magnetic resonance imaging and magnetic resonance spectroscopic imaging. Kaplan-Meier analysis shows a significant difference (p value of log–rank test to compare three stages, <0.001) between those with organ-confined (T1 or T2) tumor (n = 38; upper line), extracapsular extension (T3A, n = 21; middle line), and seminal vesical invasion (T3B, n = 8; lower line).

References

1. Obek C, Louis P, Civantos F, et al. Comparison of digital rectal examination and biopsy results with the radical prostatectomy specimen. J Urol. 1999;161:494–498. - PubMed
1. Mettlin CJ, Black B, Lee F, et al. Workgroup 2. Screening and detection: Reference range/clinical issues of PSA. Cancer. 1993;71:2679–2680. - PubMed
1. Salomon L, Colombel M, Patard JJ, et al. Value of ultrasound-guided systematic sextant biopsies in prostate tumor mapping. Eur Urol. 1999;35:289–293. - PubMed
1. Smith JA, Scardino PT, Resnick MI, et al. Transrectal ultrasound versus digital rectal examination for the staging of carcinoma of the prostate: Results of a prospective multi-institutional trial. J Urol. 1997;157:902–906. - PubMed
1. Partin AW, Kattan MW, Subong EN, et al. Combination of prostate-specific antigen, clinical stage, and Gleason score to predict pathological stage of localized prostate cancer: A multi-institutional update. JAMA. 1997;277:1445–1451. - PubMed

Pretreatment endorectal magnetic resonance imaging and magnetic resonance spectroscopic imaging features of prostate cancer as predictors of response to external beam radiotherapy - PubMed (original) (raw)