Smoking and lung cancer in Harbin, northeast China.

BACKGROUND: We studied the relationship between smoking and lung cancer risk in Harbin, Heilongjiang province, northeast China, an area with a very high baseline risk of lung cancer in both sexes, using data from a case-control study of lung cancer conducted between 1987 and 1990. PATIENTS AND METHODS: Cases were 218 patients with incident, histologically confirmed lung cancer and controls were 436 patients admitted to the same hospital with non-neoplastic and non-lung diseases. RESULTS: Compared with never-smokers, the multivariate odds ratio (OR) for current smokers was 3.47 [95% confidence interval (CI) 2.31--5.20], and for ex-smokers 1.53 (95% CI 0.81--2.87). Lung cancer risk increased by 20% (95% CI 14% to 28%) for an increment of 5 years in smoking duration, and by 29% (95% CI 15% to 45%) for an increment of five cigarettes per day. The OR for smokers reporting occupational exposure to selected known or likely lung carcinogens was 7.22, compared with non-smokers without occupational exposure. CONCLUSIONS: This study further confirms that cigarette smoking is a strong determinant of lung cancer also in this high-risk area of northeast China.