Objective:To explore the sex-based heterogeneity in demographic and pathological trends of lung cancer during the past 30 years.Methods:Patients with primary lung cancer who received surgical treatment in the Department of thoracic surgery, Shanghai Pulmonary Hospital Tongji University from 1989 to 2018 were retrospectively analyzed. The differences between male and female patients in age, smoking history, pathological stage and type were compared. Mann- Kendall trend test was performed for trend analysis. Results:A total of 58 433 patients were included in this study, encompassing 30 729(52.6%) men and 27 , 704(47.4%) women. Compared with male patients, female patients were younger(56.0 years old vs. 59.7 years old), and had a higher proportion of non-smokers(98.3% vs. 52.3%), stage Ⅰ lung cancers(60.6% vs. 49.3%), and adenocarcinoma(93.7% vs. 56.1%, all P-values <0.001). Trend analyses revealed that the proportion of female patients increased year by year, and surpassed males in 2015, with the current ratio of male to female being 1∶1.5. After 2013, the age of onset in females was getting younger, and the average age decreased from 58.7 years old to 54.7 years old( P=0.02). The decrease in the proportion of smoking patients was mainly reflected by male patients(from 68.5% to 31.1%, P<0.01). Stage Ⅰ lung cancers in male and females outnumbered advanced stage in 2012 and 2010, respectively, with a much higher proportion in female patients. Among male patients, adenocarcinoma has replaced squamous cell carcinoma as the most common pathological type since 2012, while in female patients adenocarcinoma remained the most common pathological type of lung cancer, and its proportion continued to increase reaching over 98%. Conclusion:A dramatic change in gender distribution was noticed during the past 30 years. Female patients became the primary population in surgically-treated lung cancers, with a trend of getting younger. The proportion of smokers and squamous cell carcinoma decreased significantly in male patients, and adenocarcinoma has become the most common pathological type of lung cancer. The proportion of stage Ⅰ lung cancers was on a dramatic rise, with the popularization of CT screening for lung cancer.