NEW research suggests that patients with prostate cancer treated with radiotherapy may have an increased risk of developing bladder cancer or lung cancer. The study, carried out by Steven Monda, University of California Davis, Sacramento, USA, and colleagues, found that the risk of developing and dying from these other cancers was higher amongst patients treated with radiotherapy compared to those treated with radical prostatectomy alone, regardless of whether brachytherapy or external beam radiation therapy (EBRT) was used.
The research team used SEER-17 data from 2000–2019 in order to compare rates of secondary malignancy and related deaths in patients with prostate cancer being treated with radical prostatectomy, EBRT, brachytherapy, ERBT plus brachytherapy, or radical prostatectomy followed by EBRT. The study included 261,609 patients, with a median age of 64 years in all treatment groups. It was found that at a median follow-up of 11.6 years, 4,876 patients had received a bladder cancer diagnosis, while 6,891 patients had been diagnosed with lung cancer.
When comparing the results of each treatment group, it was found that patients who received treatments other than radical prostatectomy alone had an increased risk of developing bladder cancer and lung cancer. Patients who received EBRT, brachytherapy, or EBRT plus brachytherapy had a higher risk of death from bladder cancer or lung cancer. Additionally, it was found that hazard ratios for lung cancer diagnosis and death were lower than those for bladder cancer diagnosis and death.
Monda and colleagues also observed that the incidence of bladder cancer 10 years after radiotherapy was roughly twice the incidence in patients who had radical prostatectomy (0.35 and 0.15 per 100 person-years, respectively). However, the researchers noted that this is a small absolute rate, and that “with these numbers, 500 person-years of radiation versus radical prostatectomy would be needed to observe one additional case of bladder cancer.” They concluded: “For older patients, this is likely not clinically significant. For younger men with longer life expectancies, however, this increased risk of bladder cancer may factor into initial treatment decisions for prostate cancer.”
