Improved survival for patients with prostate cancer receiving high-dose-rate brachytherapy boost to EBRT compared with EBRT alone

Introduction Escalating or ”boosting” radiation dose to prostate cancer (PCa) by adding HDR to external radiation is a standard treatment for PCa with theoretical advantages for men. Previous randomised controlled studies have demonstrated improved biochemical control by dose-escalation with external radiation and with HDR but no improvement in decreasing PCa mortality. We have been using HDR for PCa for 20 years and wondered if HDR in our men improved survival. Materials and Methods We performed a retrospective review of patients with localised prostate adenocarcinoma. Follow up with regular PSA testing was performed in all patients, and toxicity data was available for the 3DCRT+HDR cohort by IPSS scoring. Statistical analysis was performed with Stata, using a multivariable Cox regression model. Survival was assesesed with Kaplan-Meyer curves and log-rank statistics. Results 654 patients were treated during the study period, with median follow-up of almost 10 years. 439 patients were treated with 3DCRT alone, receiving 70 Gy in 35#. 215 patients had a HDR boost (20Gy in 4#) after 3DCRT (46 Gy in 23#). There was a long term disease-specific survival advantage of approximately 18% at 15 years in all patients. There were few severely symptomatic patients at 5 years, and there was good recovery from the initial post-treatment decline in erectile function. Conclusions In our cohort, overall and disease-specific survival were better in the men treated with the addition of HDR to 3DCRT, most obvious in men with high risk disease. The toxicity profile was acceptable, with low rates of severe bowel toxicity. Our results are consistent with hypothesis that there is more benefit from brachytherapy than dose escalation of external beam radiotherapy.

Kendrick Koo

The Alfred Hospital

Kendrick is a radiation oncology registrar based at the Alfred Hospital. He has recently completed a PhD in cancer genomics.