Radiotherapy in metastatic castration resistant prostate cancer patients with oligo-progression during abiraterone-enzalutamide treatment: a mono-institutional experience.

BACKGROUND: Some patients experience oligo-progression during androgen receptor targeted therapy (ARTT) treatments. This progression might not indicate a real systemic drug resistance, but a selective monoclonal resistance. With the aim to delay the start of new line treatments we treated oligo-progressive sites with radiotherapy. METHODS: From June 2011 to Febrary 2019, 29 consecutive metastatic castration resistant prostate cancer (mCRPC) patients were submitted to radiotherapy for oligo-progression (1-3 sites) during ARTT for a total of 37 lesions treated. Thirty-one (83.8%) lesions were treated with conformal radiotherapy and 6 (16.2%) with stereotactic radiotherapy. After radiotherapy all patients continued ARTT. RESULTS: Median OS (calculated from ARTT start) was 46,6 months (range 4.4-97.5 months), 2 and 3-year OS were 82.8 and 70.7%, respectively. Median PFS was 18,4 months (range 4.4-45.3 months), 2 and 3-year PFS were 38.3 and 8.5%, respectively. Median overall duration of ARTT treatment was 14.8 months (range 4.4-45.3 months) and median duration of ARTT after radiotherapy was 4.6 months (range 1-33.8 months). Patients submitted to radiotherapy > 6 months from the start of ARTT presented a better PFS (p < 0.001) and a trend toward a better OS (p = 0.101). None patient presented RT and drug related toxicities. CONCLUSIONS: Radiotherapy of oligoprogressive sites may prolong the duration of disease control under ARTT in mCRPC patients with a possible delay in the start of new line treatment. Patients progressing within 6 months from the start of ARTT did not benefit from this approach. More studies are necessary to confirm our results and to evaluate other prognostic factor in order to select patients with high benefit from this approach.

Moderate Hypofractionation in Patients with Low-risk Prostate Cancer: Long-term Outcomes.

BACKGROUND/AIM: To evaluate outcomes in patients with low-risk prostate cancer treated with hypofractionated radiotherapy (HyRT). PATIENTS AND METHODS: Between April 2004 and December 2015, 175 patients with low-risk prostate cancer were treated with HyRT 60 Gy in 20 fractions with or without image guidance and reduction of margin from clinical target volume to planning target volume. RESULTS: The median follow-up was 66 months. The 8-year overall survival for the whole patient cohort was 88.9%. The 8-year biochemical no evidence of disease was higher in patients treated with image-guided HyRT (98.8% vs. 88%, p=0.023). During treatment, patients treated with image-guided HyRT presented a lower rate of grade 1-2 gastrointestinal toxicity (25.3% vs. 42.2%, p=0.001). At the last follow-up, the grade 1 Gastro-intestinal toxicity rate was 4.0% and the grade 1-2 genito-urinary toxicity rate was 25.1%. CONCLUSION: Our study demonstrated the efficacy of the schedule used with a low rate of acute and late toxicities. Therefore, reduction of margins with image-guided HyRT is safe.