Survival in patients with metachronous second primary lung cancer

Abstract

Rationale: Four to 10% of patients with non-small cell lung cancer subsequently develop a metachronous second primary lung cancer. The decision to perform surveillance or screening imaging for patients with potentially cured lung cancer must take into account the outcomes expected when detecting metachronous second primaries.

Objectives: To assess potential survival differences between patients with metachronous second primary lung cancer compared to matched patients with first primary lung cancer.

Methods: We retrospectively reviewed patients diagnosed with lung cancer at the Cleveland Clinic (2006-2010). Metachronous second primary lung cancer was defined as lung cancer diagnosed after a 4-year, disease-free interval from the first lung cancer, or if there were two different histologic subtypes diagnosed at different times. Patients with first primary lung cancer diagnosed in the same time period served as control subjects. Propensity score matching was performed using age, sex, smoking history, histologic subtype, and collaborative stage, with a 1:3 case-control ratio. Survival analyses were performed by Cox proportional hazards modeling and Kaplan-Meier estimates.

Measurements and main results: Forty-four patients met criteria for having a metachronous second primary lung cancer. There were no statistically significant differences between case subjects and control subjects in prognostic variables. The median survival time and 2-year overall survival rate for the metachronous second primary group, compared with control subjects, were as follows: 11.8 versus 18.4 months (P = 0.18) and 31.0 versus 40.9% (P = 0.28). The survival difference was largest in those with stage I metachronous second primaries (median survival time, 26.8 vs. 60.4 mo, P = 0.09; 2-year overall survival, 56.3 vs. 71.2%, P = 0.28).

Conclusions: Patients with stage I metachronous second primary lung cancer may have worse survival than those who present with a first primary lung cancer. This could influence the benefit-risk balance of screening the high-risk cohort with a previously treated lung cancer.

Keywords: lung cancer screening; lung cancer surveillance; second primary lung cancer.