To evaluate the risk of second malignancies after seed migration in prostate cancer patients treated with I-125 free seeds brachytherapy.
Data from 2067 prostate cancer patients treated with I-125 free seeds brachytherapy in three Canadian centers were analyzed. Kaplan-Meier method was used to estimate the 5- and 7-year biochemical relapse-free and overall survival between patients who experienced or not seed migration.
Mean age and Median follow-up was 64 years and 44 (range 1-147) months, respectively. Seed migration occurred in 365 of 2067 patients (17.7%). The 5-, 7-year biochemical relapse-free and overall survival for the entire cohort was 96%, 91.7% and 95.9%, 93.7%, respectively. Second malignancies occurred in 4 of 365 patients (1.1%) and 21 of 1702 patients (1.2%) in patients with or without seed migration, respectively (p=0.827). Lung cancer represented the most frequent second malignancy observed and occurred in 6 patients, all in the no seed migration group. The other second malignancies observed in the no seed migration group included: larynx (3 patients), colon (2 patients), esophagus (2), pancreatic (2), renal, myeloma, glioblastoma, non-Hodgkin’s lymphoma (1) and 2 unknown. In the seed migration group, the second malignancies observed were chronic myeloid leukemia (1), colo-rectal cancer (2) and nasopharynx (1).
These results do not support an increased risk of second malignancies, particularly lung cancer with seed migration after I-125 free seeds brachytherapy for prostate cancer patients. Due to the low rate of second malignancies observed in this cohort, further studies with longer follow-up are required to better correlate seed migration and second malignancies.