Association between postoperative radiotherapy for young-onset nonsmall cell lung cancer and risk of second primary malignancies: comparative study.

BACKGROUND

The most common form of therapy for nonsmall cell lung cancer (NSCLC) in early stage is surgery-based combination therapy, including radiotherapy and immunotherapy. However, postoperative radiotherapy (PORT) of cancer is correlated with increasing risk of second primary malignancy (SPM), especially young-onset cancer cases. The authors aimed to quantify the risks of SPM associated with PORT treatment for young‑onset NSCLC in early stage.

METHODS

The authors screened for SPM that developed over 5 years since the diagnosis of NSCLC. Using the data from the Surveillance, Epidemiology, and End Results database, PORT-correlated risks were estimated with multivariate Logistic regression analysis. Moreover, Fine-Gray's competing risk regression analysis was used to calculate the cumulative incidence of SPMs.

RESULTS

Among the 30 308 young-onset NSCLC patients in early stage undergoing surgery, a total of 3728 patients have received PORT. Logistic regression analyses showed that PORT showed substantial correlation with elevated risks of second solid malignancies [relative risks (RR)=1.31; 95% CI: 1.17-1.46], lung cancer (RR=1.23; 95% CI: 1.07-1.42), breast cancer (RR=1.74; 95% CI: 1.16-2.74), and colon and rectum cancers (RR=1.37; 95% CI: 1.07-2.06) as well as a negligible risk of second hematologic malignancies (RR=1.15; 95% CI: 0.82-1.67). The cumulative incidence of SPMs revealed similar findings. Higher RR was obtained in NSCLC patients aged 60-69 years (RR=1.33), in white race (RR=1.36), diagnosed in 1975-2000 (RR=1.23) and 2001-2015 (RR=1.40), or diagnosed with lung adenocarcinoma (RR=1.55).

CONCLUSION

PORT for young-onset NSCLC in early stage was correlated with elevated risks of SPMs (lung cancer, breast cancer, as well as colon and rectum cancers), supporting the need for long-term surveillance of these patients.