Session Item

To analyze the clinical outcomes and toxicities of patients older than 75 years treated at our institution with hypofractionated treatments (IMRT and SBRT) to prostate and seminal vesicles volumes alone, as well as the risk factors associated with greater biochemical relapse.

Retrospective, descriptive and observational study of 90 patients older than 75 years with organ-confined prostate cancer treated with hypofractionated treatments for prostate volume +/- seminal vesicles (IMRT 20Fx/60Gy and SBRT 5Fx/36.25Gy) at the Centro de Radioterapia Dean Funes. None of the patients received pelvic lymph node irradiation. The data extracted from the institutional medical records of the patients treated with their respective follow-ups were analyzed. To assess risk factors (PSAi ≥20, ISUP≥4, T≥2c, high-grade PIN, IPN, compromised cylinders ≥50%, high-grade NCCN), univariate and multivariate analysis with Cox regression were performed. To assess overall survival, biochemical relapse-free survival (BRFS), and metastasis-free survival (MFS), Kaplan Meier curves were performed.

90 patients older than 75 years were treated, with a mean age of 78.3 years. The mean follow-up was 3 years. 60% presented high risk according to NCCN classification, 40% unfavorable intermediate risk. Androgen blockade was performed in 60% of the patients. 86% performed IMRT and 14% SBRT. No patient had to discontinue treatment. At follow-up, 90% of the patients were alive, 5% had biochemical relapse and 2% had distant metastases. The BRFS at 2 years was 100% and at 3 years 95%. The MFS was 100% at two years and 97% at 3 years. Among the risk factors analyzed, high-grade PIN (p=0.01), involvement >50% of cylinders in the biopsy (p=0.001) and T≥2c (p=0.04) were predictors of biochemical relapse in univariate analysis; however, only T≥2c(p=0.02) and high-grade PIN(p=0.03) were confirmed as independent variables in the multivariate analysis. Regarding toxicity, 60% had acute toxicity GU G 1-2 (dysuria-polyaquiuria) and 1% G3. At the GI level, 25% had G1-2 toxicity (diarrhea) and 4% G3. G1-2 late GU toxicity was 17% and G3 1%, G1-2 late GI toxicity was 9% and G3 1%. There was no statistically significant difference in BRFS (p=0.31) or acute or late toxicity depending on the applied technique.

The results obtained in this work agree with the international literature in the general population, therefore the omission of pelvic radiotherapy and hypofractionated radiotherapy to the prostate volume in elderly patients with organ-confined prostate cancer is a safe and effective treatment, with excellent local control and good tolerance. Longer follow up is need to evaluate the pattern of recurrences.