Risk of Developing a Second Primary Cancer in Male Breast Cancer Survivors: A Systematic Review and Meta-Analysis

Abstract

Abstract

Background:

With increasing survival after cancer diagnosis, second primary cancers (SPCs) are becoming more prevalent. We investigated the incidence and site of non-breast SPC risks following male breast cancer (BC).

Methods:

PubMed, Embase and Web of Science were systematically searched for studies reporting standardized incidence ratios (SIRs) for SPCs published by March 2022. Meta-analyses used the generic inverse-variance method, assuming a random-effects model. We evaluated SIRs for overall SPCs, site-specific risks, by age at BC onset, time since BC onset and geographic region. We assessed study quality using routine techniques.

Results:

Eight population-based retrospective cohort studies were identified. SIRs ranged from 1.05 to 2.17. The summary SIR estimate was 1.27 (95%CI: 1.03-1.56, I2: 86%) and there were increased colorectal (SIR: 1.29, 95%CI: 1.03-1.61), pancreatic (SIR: 1.64, 95%CI: 1.05-2.55) and thyroid (SIR: 5.58, 95%CI: 1.04-30.05) SPC risks. When an outlying study was excluded, the summary SIR for men diagnosed with BC before age 50 was 1.50 (95%CI: 1.21-1.85), significantly higher than men diagnosed at older ages (SIR: 1.14, 95%CI: 0.98-1.33).

Conclusions:

Male BC survivors are at elevated risks of developing second primary colorectal, pancreatic, and thyroid cancers. The estimates may assist their clinical management and guide decisions on genetic testing.