Prognostic impact of radiation therapy to the primary tumor in patients with non-small cell lung cancer and oligometastasis at diagnosis.

Abstract

We investigated prognostic factors associated with survival in patients with non-small cell lung cancer (NSCLC) and oligometastatic disease at diagnosis, particularly the influence of local treatment to the primary site on prognosis. From January 2000 through June 2011, 78 consecutive patients with oligometastatic NSCLC (<5 metastases) at diagnosis underwent definitive chemoradiation therapy (≥45 Gy) to the primary site. Forty-four of these patients also received definitive local treatment for the oligometastases. Survival outcomes were estimated using the Kaplan-Meier method, and risk factors were identified by univariate and multivariate analyses. Univariate Cox proportional hazard analysis revealed better overall survival (OS) for those patients who received at least 63 Gy of radiation to the primary site (P=.002), received definitive local treatment for oligometastasis (P=.041), had a Karnofsky performance status (KPS) score >80 (P=.007), had a gross tumor volume ≤124 cm³ (P=.002), had adenocarcinoma histology (P=.002), or had no history of respiratory disease (P=.016). On multivariate analysis, radiation dose, performance status, and tumor volume retained significance (P=.004, P=.006, and P<.001, respectively). The radiation dose also maintained significance when patients with and without brain metastases were analyzed separately. Tumor volume, KPS, and receipt of at least 63 Gy to the primary tumor are associated with improved OS in patients with oligometastatic NSCLC at diagnosis. Our results suggest that a subset of such patients may benefit from definitive local therapy.