How long is cessation of preoperative smoking required to improve postoperative survival of patients with pathological stage I non-small cell lung cancer?

Background Smoking can cause non-small cell lung cancer (NSCLC). However, the effects of preoperative smoking on tumor progression are not well-known. In addition, the duration of smoking cessation that can provide NSCLC patients with smoking history similar postoperative prognosis as that of nonsmokers remains unknown. This study aimed to investigate the period of smoking cessation that may "compensate" for past smoking history regarding postoperative survival in cases of resected pathological stage I NSCLC by examining the relationship between clinicopathological factors and preoperative smoking. Methods We retrospectively examined clinicopathological factors including preoperative smoking status and postoperative survival in 453 patients with pathologically proven stage I NSCLC at our Institute. Smoking status was evaluated using the following four parameters: cigarettes per day, number of years of smoking, pack-years, and number of years since smoking cessation. Results Pathological factors that reflect tumor invasiveness including vascular invasion (VI) and pleural invasion (PL) were associated with the degree of preoperative smoking in adenocarcinomas, particularly invasive diameters of 2-3 cm. Such a relationship was not identified for non-adenocarcinomas. Heavy smoking status was significantly related to PL in lepidic or papillary predominant adenocarcinomas and to VI in acinar or solid predominant adenocarcinomas. Former smokers who quit smoking for ≥10 years had similar postoperative survival as non-smokers for adenocarcinoma ≤3 cm. Conclusions Accumulative smoking habit correlated with VI and PL, particularly in 2-3 cm adenocarcinoma, whereas larger adenocarcinomas and non-adenocarcinomas of any size appear to grow and become invasive independent of preoperative smoking status. Longer smoking cessation ≥10 years can result in postoperative survival similar to that of non-smokers with adenocarcinomas ≤3 cm. Current smokers should quit smoking immediately to ensure longer survival even though they suffer from small-sized lung adenocarcinomas in the future.