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Secondary primary tumors following iodine-125 low-dose-rate brachytherapy for localized prostate cancer
Kojiro Niwa1, Koji Iinuma2, Masahiro Nakano3
1Department of Urology, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu, Gifu, 501-1194, Japan.
Background:
Low-dose-rate brachytherapy with iodine-125 (LDR-BT) is an established curative radiation treatment modality for localized prostate cancer (PCa). This study aimed to evaluate the long-term incidence of secondary primary tumors (SPTs) following LDR-BT in Japanese patients with localized PCa and identify predictive factors associated with SPTs.
Methods And Materials:
We retrospectively reviewed the clinical records of 478 consecutive patients with localized PCa who underwent LDR-BT at the Gifu University Hospital. This study's primary endpoint was SPTs incidence, including bladder and rectal/anal cancers. The secondary endpoint was the identification of risk factors for LDR-BT that predicted SPTs development.
Results:
After a median follow-up period of 105 months, SPTs developed in 13 patients (2.7%). Bladder cancer and rectal/anal canal cancer were observed in seven (1.5%) and six (1.3%) patients, respectively. Multivariate analysis showed that a biologically effective dose (BED) ≥ 197 Gy was associated with increased risk of SPTs (hazard ratio 4.145; 95% confidence interval 1.108-15.498; p = 0.035).
Conclusions:
The incidence of SPTs following LDR-BT was relatively low. In multivariate analysis, BED ≥ 197 Gy may be associated with an increased risk of SPT occurrence. Adequate tumor control can be achieved through appropriate radiation dose administration; carefully planned long-term follow-up may be beneficial for SPTs early detection.
