medwireNews: Men who receive radiotherapy for localized prostate cancer have a significantly elevated risk for a second primary cancer relative to their counterparts not exposed to radiotherapy, suggests a database analysis.
The investigators stress that both “the incidence and risk of developing a second primary cancer were low,” but highlight that the risk increased over time.
“Moreover, prostate cancer is common, occurring in approximately 1 in 8 men in the US, and even a low-risk event can have consequences for a large absolute number of patients,” they continue. “Careful consideration of risks and benefits among accepted treatment modalities is therefore paramount.”
For the study, the researchers collated data from the Veterans Affairs Corporate Data Warehouse on 143,886 men with no history of cancer before being diagnosed with T1–T3 prostate cancer during 2000–2015. Patients were aged a median of 65 years at diagnosis and just under two-thirds (63.3%) were White.
In all, 36.8% of the patients received primary radiotherapy in the year after diagnosis, and of the remaining 63.2% who did not, the majority (65.7%) underwent active surveillance, medical management, or observation, while the rest (34.3%) had surgery.
As reported in JAMA Network Open, the incidence of a second primary cancer at more than a year after the prostate cancer diagnosis was higher among patients who did versus those who did not receive radiotherapy, at 3.7% and 2.5%, respectively.
Multivariable analysis adjusting for demographic and clinical covariates showed a significantly increased risk for second primary cancer in the radiotherapy versus non-radiotherapy cohort in the 5 years after the prostate cancer diagnosis, at a hazard ratio (HR) of 1.24.
Radiotherapy-treated patients remained at increased risk for a second primary cancer over time, with significant HRs for the 5–10, 10–15, and 15–20 years after diagnosis of 1.50, 1.59, and 1.47, respectively.
The results were consistent in a sensitivity analysis in which the control group included just patients who underwent surgery, and also in an analysis including a smoking history covariate, report Hilary Bagshaw and colleagues from Stanford University in Palo Alto, California, USA.
“This study’s findings suggest that it is important that shared decision-making among patients with prostate cancer includes discussion of late toxic effects, including the risk of developing a second primary cancer, and that the possibility of developing a second primary cancer after radiotherapy be considered during evaluation of symptoms among survivors,” concludes the team.
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