Histology and smoking history of lung cancer cases and implications for prevention in Thailand

Lung cancer is now a major public health problem in Thailand. This descriptive study looked at the issue of whether tumor histology varied with smoking status among lung cancer patients in Bangkok, Thailand.

A retrospective descriptive study was made of the 1,600 Thai patients with histologically proven lung cancer admitted to University of Siriraj Hospital between 1967 and 1991. Cigarette smoking histories were obtained, and histologies were classified and related to tobacco consumption.

Overall, 78% were smokers, 72% being heavy smokers. The male to female ratio was 13:1 for smokers and 0.4:1 for nonsmokers. There were 29% squamous cell, 29% adenocarcinoma, 24% large cell, and 13% small cell carcinomas. Squamous cell carcinoma was significantly more frequent among cases with a history of smoking Thai cigarettes, which are known (from other studies) to be high in tar and nicotine, than among nonsmoking cases. Among the 350 nonsmokers, 252 of whom were female, adenocarcinoma was the most common (58%).

The results suggest that Thai smokers can reduce their risk for lung cancer by quitting smoking, or by substituting lower tar brands. Antismoking programs should therefore be a public health priority. Given the prevalence of adenocarcinoma among nonsmokers, further work should be done to identify environmental causes.