Second primary bladder cancer less likely in patients treated with radical prostatectomy vs EBRT
The risk of a second primary bladder cancer (BCa) is higher in prostate cancer (PCa) patients treated with external beam radiotherapy (EBRT) than radical prostatectomy (RP), reports a recent study.
Researchers evaluated 84,397 patients diagnosed with localized PCa who underwent either RP (39 percent; n=33,252; median age at surgery 69 years) or EBRT (61 percent; n=51,145; median age at surgery 74 years). The development of a second primary BCa or renal cancer (RCa) was the primary outcome.
Over a median follow-up of 69 months, 1,660 cases of pelvic tumours were reported, most of which were of BCa (n=1,236; RCa: n=432). The cumulative incidence-derived 5-year probabilities of developing BCa and RCa were 1.06 percent and 0.37 percent, respectively, while the corresponding 10-year rates were 2.04 percent and 0.74 percent.
Stratifying by treatment received, the probabilities of BCa were significantly higher in patients treated with EBRT vs RP (5-year: 0.75 percent vs 1.26 percent; 10-year: 1.63 percent vs 2.34 percent; p<0.001). No such effect was observed for RCa (5-year: 0.32 percent vs 0.36 percent; 10-year: 0.73 percent vs 0.69 percent; p=0.4).
Multivariable competing-risk regression analyses further confirmed these results. PCa patients treated with EBRT were significantly more likely to develop a second primary pelvic cancer (hazard ratio [HR], 1.27; 95 percent CI, 1.13–1.43; p<0.001) and BCa (HR, 1.35; 1.18–1.55; p<0.001), but not RCa (p=0.4).
The detrimental effect of EBRT remained significant even when participants were stratified according to smoking status. However, patients >80 years of age did not show differing risks of a second primary tumour regardless of initial treatment.