Late second primary cancers affect 11.2% of older long-term cancer survivors

A retrospective SEER-Medicare cohort study examined late second primary malignancies among 90,261 people diagnosed with breast, prostate, colon, or rectal cancer in 2003–2011 at age 66 years or older who survived at least five years. The primary outcome was a new invasive cancer occurring at least five years after the initial diagnosis. Researchers assessed associations with demographic, clinical, and treatment characteristics using restricted mean survival time regression.

Overall, 10,116 survivors (11.2%) developed at least one late second primary malignancy, accounting for 10,220 cancers. Eight-year cumulative incidence was highest among prostate cancer survivors. Non-screen-detectable solid tumors comprised the largest category (47.8%). The most common sites were lung among colon and rectal cancer survivors (14.9% and 16.1%, respectively), urinary bladder among prostate cancer survivors (17.0%), and new-primary breast cancer among breast cancer survivors (36.5%).

More than 40% of late second primary malignancies were categorized as screen-detectable, supporting attention to survivorship care beyond five years. However, this observational study does not establish the benefit of any particular screening strategy. Findings apply to older long-term survivors of the four studied cancers; the abstract does not provide detailed adjusted estimates or absolute incidence by survivor group, and full text was unavailable for assessment.