Second primary malignancies after stereotactic body radiotherapy vs surgery for early-stage lung cancer: a U.S....

Stereotactic body radiotherapy (SABR) plays an essential role in the curative treatment of early-stage lung cancer. Second primary malignancy (SPM) has become a significant concern in lung cancer management because of the increasing number of cancer survivors. However, whether SABR increases the risk of SPMs in early-stage lung cancer remains unknown.

Patients with T1-2N0M0 primary lung cancer who underwent either surgery or SABR between 2010 and 2015 were enrolled from the Surveillance, Epidemiology, and End Results (SEER) database. A Kaplan-Meier analysis was conducted to compare the cumulative incidence of SPMs between patients who underwent radiotherapy and those who underwent surgery. Multivariable Cox regression analyses were performed to evaluate the risk of SPMs.

The study included 22,809 2-year early-stage lung cancer survivors (radiotherapy, 3236; surgery, 19,573) and 17,048 5-year survivors (radiotherapy, 1501; surgery, 15,547). 196 second haematologic cancers and 1642 second solid malignancies were diagnosed. SABR was not associated with a higher overall risk of second haematologic cancers or second solid malignancies. However, after adjusting for independent influencing factors of SPMs, SABR was associated with a 38.5% higher cumulative incidence of secondary primary lung cancer. The risk was increased only when compared to the lobectomy group.

SABR for early-stage lung cancer was not associated with a higher overall risk of developing SPMs; however, it did increase the risk of second primary lung cancers when compared to the lobectomy group. Randomised controlled trials should be conducted in the future to validate our conclusions further.