Prostate brachytherapy and second primary cancer risk: a competitive risk analysis

Area of Science:

• Oncology
• Radiation Oncology
• Urologic Oncology

Background:

• Prostate cancer is a common malignancy in men.
• Treatment options include brachytherapy and prostatectomy.
• Assessing long-term risks, such as second primary cancer (SPC), is crucial for treatment comparison.

Purpose of the Study:

• To compare the risk of SPC after [(125)I]iodine prostate cancer brachytherapy versus prostatectomy.
• To evaluate SPC risk relative to the general population.

Main Methods:

• A cohort of 1,888 prostate cancer patients treated with either brachytherapy (n=1,187) or prostatectomy (n=701) was analyzed.
• SPC incidence was determined through linkage with the Dutch Cancer Registry.
• Standardized incidence rates (SIRs) and absolute excess risks (AERs) were calculated.

Main Results:

• Overall SPC incidence did not differ significantly between brachytherapy and prostatectomy groups (Hazard Ratio: 0.87; 95% CI, 0.64 to 1.18).
• No increased SPC risk was observed compared to the general population (SIR: 0.94 for brachytherapy, 1.04 for prostatectomy).
• A higher incidence of bladder SPC was noted after brachytherapy in younger patients and within the first 4 years post-treatment, potentially due to lead time or screening bias.

Conclusions:

• Prostatectomy and brachytherapy demonstrate comparable rates of second primary cancer development.
• There is no evidence of an elevated overall cancer risk post-treatment compared to the general population.
• Further investigation into the early increase in bladder cancer risk following brachytherapy is warranted, acknowledging potential biases.