Complete resection of the primary lesion improves survival of certain patients with stage IV non-small cell lung cancer

The standard treatment for patients with stage IV non-small cell lung cancer (NSCLC) is systemic chemotherapy. However, certain patients, such as those with oligometastasis or M1a disease undergo resection of the primary lesion. We conducted a retrospective review of the records of 1,471 consecutive patients with NSCLC who underwent resection of the primary lesion for between June 2005 and May 2016. The present study included 38 patients with stage IV NSCLC who underwent complete resection of the primary lesion as first-line treatment. The median follow-up duration for the 38 patients (27 men) was 17.7 months (range, 1-82.3 months). The T factors were T1/T2/T3/T4 in 4/16/12/6 patients, respectively. The N factors were N0/N1/N2/N3 in 16/8/12/2 patients, respectively. The M factors were M1a/M1b/M1c in 19/13/6 patients, respectively. Of the 19 M1a patients, 11 were classified as cM0. We introduced the novel classification M-better/M-worse. M-better includes cM0 patients and M1b and M1c patients in whom all lesions have been locally controlled. M-worse includes cM1a patients and M1b and M1c patients in whom lesions cannot be locally controlled. The new M-better/M-worse statuses were 24/14 patients, respectively. The histology of NSCLC was adenocarcinoma/squamous cell carcinoma/others in 30/5/3 patients, respectively. The 5-year overall survival rate was 29%, and the median survival time was 725 days. Squamous cell carcinoma and M-worse were significant factors predicting poor outcomes (P=0.0017, P=0.0007, respectively). Even for stage IV NSCLC patients, resection of the primary lesion may be beneficial, especially for those with M-better status and those not diagnosed with squamous-cell carcinoma (SCC).