External beam radiotherapy increases the risk of bladder cancer in patients with prostate cancer

This study aimed to investigate the risks of bladder or rectal cancer for patients who have had surgery or external beam radiotherapy (EBRT) as a treatment for prostate cancer. This study found that radiation therapy led to a higher risk of bladder cancer, as compared to prostate surgery. 

Surgery and radiation therapy are options in the treatment of prostate cancer. Many patients achieve long-term survival after radical prostatectomy (RP; complete removal of the prostate) or external beam radiotherapy (EBRT; a radiation beam is directed at the prostate from outside the body).

The prostate is located very close to the bladder and the rectum, and treatment to the prostate could affect them. There is a risk of developing a second primary tumor after treatment for prostate cancer. A second primary tumor is unrelated to the first one and is not a spread of disease. However, the risks of developing a second tumor are unknown with current treatments for prostate cancer.

84 397 individuals with prostate cancer were included in the study. 39% were treated with RP and 61% with EBRT. Patients were followed up for an average of 69 months.

A total of 1660 (1.97%) individuals developed pelvic tumors within 5.8 yr after treatment with RP or EBRT. Of these, 1236 had bladder cancers and 432 had rectal cancers.

Patients treated with EBRT have a 72% increased risk of developing a second primary bladder cancer within 5 years when compared with patients treated with RP. There were no differences regarding the risk of developing a second primary rectal cancer between the two treatments for prostate cancer.

This study found that patients treated with EBRT for prostate cancer have an increased risk of developing a second primary bladder cancer.

This study looked back at the medical records of patients. Data collected in this way is not always complete.