Effect of Smoking Duration and Pack-Year History on Histological Subtypes of Lung Cancer

Abstract

Background: Lung cancer is the leading cause of cancer-related mortality worldwide, with smoking as the principal risk factor. The histological subtypes of lung cancer, including adenocarcinoma, squamous cell carcinoma, and small cell carcinoma, vary according to smoking history and intensity. This study investigates the effect of smoking duration and pack-year history on the histological subtypes of lung cancer in Bangladesh. Methods: A cross-sectional study was conducted at the National Institute of Diseases of the Chest and Hospital (NIDCH) from July 2007 to June 2008. A total of 98 patients with confirmed primary lung cancer were included, comprising 81 smokers and 17 non-smokers. Results: Among the 98 patients, 45% had adenocarcinoma, 28.6% squamous cell carcinoma, 16.3% small cell carcinoma, 6.1% large cell carcinoma, and 3.1% other subtypes. Smokers exhibited a higher incidence of squamous cell carcinoma (33.3%) and small cell carcinoma (19.8%), while adenocarcinoma was more common in non-smokers (88.2%). Majority (94.1%) of the patients with lesions in the upper lobe was smokers compared to 56.7% of patients with lesions in the lower lobe (p < 0.001) Ratio of upper and lower lobe tumour among smoker was roughly of 4:1. A significant association was found between smoking duration, pack-years, and the occurrence of squamous and small cell carcinoma (p < 0.001). Conclusion: Smoking duration and pack-years have a significant impact on the histological subtypes of lung cancer. Squamous cell carcinoma and small cell carcinoma are more prevalent in smokers, while adenocarcinoma is more common in non-smokers.