EBRT for prostate cancer linked to increased rates of secondary malignancies
MedWire News: Men treated with external beam radiotherapy (EBRT) for prostate cancer may have a higher risk for developing secondary bladder cancer (BC), lung cancer (LC), and renal cancer (RC) than their surgically treated counterparts, researchers report.
The study results corroborate the findings of previous research comparing EBRT with radical prostatectomy (RP), this time among a cohort of French–Canadian men.
“The rationale for the analysis stemmed from the potentially different genetic makeup of the predominantly French–Canadian population, relative to the previously studied American cohorts,” explain Pierre Karakiewicz, from the University of Montreal in Quebec, Canada, and colleagues.
The team believes that the increased rates of these secondary malignancies seen in EBRT-treated patients should be considered when patients are asked for informed consent to treatment.
The incidence rates of BC, LC, and RC at 60 and 120 months or longer after treatment were assessed among a cohort of 17,845 prostate cancer patients from the Province of Quebec who underwent either EBRT (n=9390) or RP (8455).
Multivariate analysis, adjusted for age, comorbidities, and year of treatment showed that at 60 months or more after treatment, men treated with EBRT had a 1.5-fold increased risk for BC, a 1.8-fold increased risk for LC, and a 1.9-fold increased risk for RC compared with men treated with RP.
The researchers performed the same analysis using incidence data at 120 months or more and found that, although hazard ratios for BC and RC did not reach significance, men treated with EBRT were 2.9 times more likely to develop LC than men treated with RP.
With regard to 15-year event-free survival, the absolute rate differences between EBRT and RP for BC, LC, and RC incidence were 2.8%, 2.2%, and 0.9%. These figures translate to a number needed to harm with EBRT, compared with RP, of 36 for BC, 45 for LC, and 111 for RC.
“Our findings demonstrated that EBRT is associated with higher rates of BC, LC, and RC when incident cases diagnosed 5 or more years after definitive therapy are considered,” write Karakiewicz et al in the International Journal of Radiation Oncology Biology Physics.
“These rates should be included in informed consent consideration,” the team concludes.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Sarah Guy