Risk of developing a subsequent primary lung cancer among adult non-lung cancer survivors: implications for lung cancer screening and supportive care

Background An increasing number of people are living with and beyond a cancer diagnosis. We aim to characterize the risk of developing a subsequent primary lung cancer (SPLC) among survivors of non-lung first primary cancers (FPC). Methods All adults diagnosed with cancer in Alberta between 2000 and 2021 who survived 6+ months were included. We estimated incidence rate differences and standardized incidence ratios (SIR) for SPLC compared to the cancer-free population and high-risk individuals included in a lung cancer screening trial. Multivariable Fine-Gray models were used to identify risk factors within cancer survivorship groups. Results Cancer survivors (n=180,325) have a higher risk of developing SPLC compared to those without a personal cancer history overall (SIR=1.37, 95% CI: 1.32-1.42) and at later stages (III/IV). The increase in late-stage SPLC risk was highest beyond 5 years from FPC diagnosis. Thirteen out of twenty-one FPC sites have significant increases in SPLC risk and smoking-related FPC sites carried the highest risks. For survivors of head and neck or bladder cancers, the six-year absolute risks of developing SPLC were 2.7% and 2.6%, respectively, which is higher than the thresholds commonly used for lung screening program eligibility. Five FPC sites had SIRs higher than the control arm of a lung cancer screening trial. Site-specific SPLC risk varied by age, sex, socioeconomic status, comorbidities, stage of FPC, and treatments. Conclusion Cancer survivors carry significant risks of developing SPLC yet many survivors may not be considered for long term surveillance or screening for early lung cancer detection.