Sex differentiation of smoking effect for prognosis of lung cancer - Study of 2220 cases of primary lung cancer undergone pulmonary resection

Objective. The objective of this study was to examine the clinical characteristics and the differences between the sexes as to the effects of smoking on the survival rate in lung cancer patients who had undergone lung resection in the Department of Thoracic Surgery of Tohoku University Hospital. Methods. The clinical records and Brinkman index values (number of cigarettes for day x years smoked) of 2220 patients, 1617 men and 603 women, who had undergone pulmonary resection from 1952 to 2000 at Tohoku University Hospital were reviewed. Results. The ratio of adenocarcinoma patients was higher in women than men, while men had a higher ratio of squamous cell carcinoma and large cell carcinoma. In both sexes, the 5-year survival rates of non-smokers were significantly better than those of smokers. The larger the Brinkman index value was, the lower was the incidence of adenocarcinoma. There was no significant impact of the Brinkman index on stage progression. To clarify the effect of smoking on the survival rate, we reviewed the records of patients with pathological stage IA adenocarcinoma, since most of these patients are expected to die from non-cancerous causes. As a result, the outcome in male smokers in terms of overall survival was significantly worse than that in non-smokers. There was no significant difference, however, in survival between smokers and non-smokers, based on death due to lung cancer. Conclusion. It is suggested that smoking-related deaths resulting from causes other than cancer were not negligible in male surgically treated lung cancer patients. Although the impact of the effect of smoking on the survival of female patients with stage Ia adenocarcinoma was not clear, the overall survival of lung cancer patients with a history of smoking was worse than that of non-smokers in both sexes. As described above, smoking cessation is still an important issue in Japan.