Objectives: To determine the failure rate of brachytherapy as definitive treatment for localized prostate cancer in transplant and otherwise immunosuppressed patients compared with patients not undergoing immunosuppressive therapy.
Methods: A retrospective study of 314 patients treated with brachytherapy for prostate cancer between July 1995 and March 2007, 7 of whom were previously transplanted and currently on immunosuppression (4 heart transplants, 3 renal transplants), and 10 of whom were on immunosuppression for other medical conditions. Outcomes were defined by both American Society for Radiation Oncology (ASTRO) and Phoenix definitions of biochemical failure.
Results: The mean patient age at implant was 67.3±7.3 years; mean follow-up was 7.5±2.8 years, with a minimum follow-up of 3 years. In the nonimmunosuppressed group, a 15.8% failure rate by the ASTRO definition and 13.6% rate by the Phoenix definition were observed. When excluding patients with previous external beam radiation and/or neoadjuvant hormone therapy, a 13.6% failure rate by the ASTRO definition and 11.4% rate by the Phoenix definition were observed. Within the transplanted patient subset, failure rates by both ASTRO and Phoenix definitions were 14.3%. For all immunosuppressed patients, failure rates were 11.8% by both definitions. While performing a Fisher exact test, there was no statistical difference in failure rates between all groups by either definition of failure.
Conclusions: Immunosuppressed prostate cancer patients treated by brachytherapy seem to enjoy similar cancer control rates as the similarly treated nonimmunosuppressed population. It is recognized, however, that a much larger cohort of immunosuppressed patients would need to be studied to demonstrate statistical equivalence.