Outcomes following brachytherapy boost for intermediate- and high-risk prostate cancer: A retrospective bicenter study by the SFRO brachytherapy group.

INTRODUCTION: Radiotherapy dose escalation improves biochemical control in intermediate- or high-risk prostate cancer. Brachytherapy boost was shown to further improve biochemical control compared to radiotherapy alone in three randomized trials. The SFRO brachytherapy group sought to evaluate the efficacy and toxicity of BT-boost for intermediate and high-risk prostate cancer in real life, and to determine prognostic factors for efficacy and toxicity. MATERIAL AND METHOD: A retrospective study was conducted, including all patients with intermediate- or high-risk prostate cancer treated with a combination of external beam radiotherapy (EBRT) and high dose-rate brachytherapy boost (HDR-BB), from 2006 until December 2019 at two centers. Patient characteristics, initial disease, treatment and follow-up were collected. RESULTS: 709 patients from two centers were analyzed given a short follow-up in the other centers. Out of those, 277 were intermediate risk (170 favorable and 107 unfavorable) and 432 were high risk. The median EBRT and HDR-BB doses were 46 Gy (35-50) and 14 Gy (10-20). After a median follow-up of 62 months, biochemical control at 5 years was 87.5 % for the overall population, 91 % and 85 % for intermediate- and high-risk cancers, respectively. At 5 years, biochemical and clinical relapse-free survival, metastasis-free survival and local control rates were 83 %, 90 % and 97 % respectively. 5-years overall survival was 94 %. Late grade 2 or higher GU or GI toxicity was found in 36 patients (5 %) and 9 patients (1.3 %). CONCLUSION: This bicenter analysis shows the efficacy and tolerability of HDR-BB as a complement to external radiotherapy. Further improvements such as combination with new hormonal agents or new brachytherapy-radiotherapy fractionation regimens are warranted to improve further the outcomes and therapeutic ratio.

[Non-metastatic prostate cancer treated with exclusive radiotherapy: prognosis of patients according to lymph node radiologic or surgical assessment method. Multivariate retrospective analysis]. / Cancers de prostate non métastatiques traités par radiothérapie exclusive: devenir des patients selon la méthode d'évaluation ganglionnaire radiologique ou chirurgicale. Une analyse rétrospective multivariée.

PURPOSE: To compare retrospectively the outcome of localized prostate cancers treated by curative external radiotherapy in which the negative lymphatic status was either surgically or radiologically assessed. METHODS AND MATERIALS: From January 1986 to December 1995, 112 patients with localized prostate cancers were found to have no evidence of lymphatic disease in the pelvis. N0 status was assessed either surgically (61 patients, group pN-) or after a CT scan procedure (51 patients, group cN0). The treatment consisted of conventional external radiotherapy using a four-fields box technique to a total dose of 65 Gy. The pelvis was never irradiated. RESULTS: The two groups did not statistically differ according to age, PSA level, Gleason score, T stage and hormonal therapy. Actuarial NED survival rates were 80% and 60% at five and ten years respectively. At ten years, the actuarial NED survival rates were 78% and 34% in the pN- and cN0 groups respectively (p = 0.003). The multivariate analysis corroborated the positive impact of lymphatic dissection before radiotherapy on disease free survival of T1-T2 patients, but not for T3 stages. CONCLUSIONS: This retrospective study suggests the inability of CT scan to accurately evaluate the lymph node status in carcinoma of the prostate. Systematic ilio-obturator nodal dissection is strongly recommended in early stages before curative radiotherapy. Only pN-patients should be included in high dose conformal irradiation trials.