1231P Significant impact of preoperative smoking period on postoperative prognosis in patients with surgically resected non-small cell lung cancer

The pack-year index, which is calculated by multiplying a smoking period by the number of cigarette packs smoked per day, is frequently used to investigate the risk of developing lung cancer. Notably, however, whether the smoking period or the number of packs per day is more predictive of postoperative prognosis remains unclear in non-small cell lung cancer (NSCLC) patients who receive curative lung resection. Initial screening included 2,055 consecutive lung cancer patients who had underwent curative lung resection between 2000 and 2016 at a single center in Japan. Data from 1,134 NSCLC patients with smoking history were ultimately analyzed. Time-dependent areas under the curve (AUCs) were used to compare diagnostic accuracy. In univariate analysis the number of packs smoked per day was not a significant predictor of disease-free survival (DFS; p= 0.2387) or overall survival (OS; p= 0.1357). In multivariable analysis smoking period was an independent predictor of DFS and OS (both p< 0.0001). Time-dependent smoking period AUCs were superior to those of number of packs smoked per day. In subgroup analyses patients with a smoking period of ≥ 40 years had significantly shorter DFS and OS than those with a smoking period of < 40 years, independent of sex, clinical stage, and histological type. In the present study smoking period was a significant prognostic indicator in NSCLC patients who underwent curative lung resection.Smokers may need to instigate a non-smoking period, rather than reduce the number of packs smoked per day.