Safety of high-dose-rate brachytherapy in patients with prostate cancer and inflammatory bowel disease: A case series.

Introduction: Inflammatory bowel disease (IBD) is a relative contraindication to external beam radiation therapy (EBRT) for prostate cancer patients due to fear of increased risk of gastrointestinal (GI) toxicity. High-dose-rate (HDR) brachytherapy, capable of minimizing radiation dose to surrounding tissues, is a feasible alternative. Given limited data, this study examined the safety profile of HDR brachytherapy in this setting. Material and methods: We conducted a retrospective review of patients with localized prostate cancer and IBD treated with HDR brachytherapy at the University of California San Francisco (UCSF), between 2010 and 2022. Eligibility criteria included biopsy-proven prostate cancer, no distant metastases, absence of prior pelvic radiotherapy, IBD diagnosis, and at least one follow-up visit post-treatment. Results: Eleven patients were included, with a median follow-up of 28.7 months. The median dose administered was 2700 cGy (range, 1500-3150 cGy) over 2 fractions (range, 1-3 fractions). Two patients also received EBRT. Rectal spacers (SpaceOAR) were applied in seven patients. All patients experienced acute genitourinary (GU) toxicity, ten of which were grade 1 and one was grade 2. Eight patients experienced late grade 1 GU toxicity, and three patients had late grade 2 GU toxicity. GI toxicities were similarly low-grade, with six grade 1 acute toxicity, no grade 2 or higher acute toxicity, six grade 1 late toxicity, and one late grade 2 GI toxicity. No grade 3 or higher acute or late GI or GU toxicities were reported. Conclusions: HDR brachytherapy appears to be a safe and tolerable treatment modality for patients with prostate cancer and IBD, with minimal acute and late GI and GU toxicity. These findings warrant multi-institutional validation due to small sample size.

Safety of high-dose rate (HDR) brachytherapy for patients with prostate cancer and history of prior chemoradiation for rectal cancer: A case series.

PURPOSE: A history of prior pelvic radiation therapy (RT) for rectal cancer is a relative contraindication for definitive RT for prostate cancer. High-dose-rate (HDR) brachytherapy can significantly limit the dose to surrounding tissues compared to external beam RT. However, there is limited data surrounding its safety in patients with prior pelvic RT. METHODS AND MATERIALS: A retrospective chart review was performed at the University of California, San Francisco to identify patients diagnosed with prostate cancer with a history of pelvic RT for rectal cancer who were treated with high-dose-rate brachytherapy (HDR-BT) between 2006 and 2022. Inclusion criteria were biopsy-confirmed prostate cancer with no evidence of distant disease on clinical examination or imaging, and at least one post-treatment clinic appointment. RESULTS: Seven patients were treated with salvage HDR-BT at a median interval of 17.7 years after RT for rectal cancer. HDR-BT doses included 3600 cGy in six fractions (n = 5), 2700 cGy in 2 fractions (n=1), or 2800 cGy in four fractions (n = 1). There was no acute grade ≥2 gastrointestinal toxicity, and 1 patient developed late grade 2 rectal bleeding. Two patients developed acute grade 2 genitourinary toxicity consisting of urinary frequency and urgency, which persisted through long-term follow up. At a median follow up of 29.5 months after HDR brachytherapy, one patient developed regional and distant failure, and another had seminal vesicle recurrence. CONCLUSIONS: HDR-BT is a safe treatment for patients with prostate cancer who previously received RT for rectal cancer. Further studies are needed to better characterize the long-term toxicity of HDR-RT in this population.