Morbidity and mortality in relation to cigarette smoking in Shanghai, China. A prospective male cohort study.

OBJECTIVE

To evaluate prospectively the health risk of cigarette smoking in middle-aged men in Shanghai, China.

DESIGN

Prospective cohort study with annual follow-up.

PARTICIPANTS

A total of 18 244 male residents of Shanghai, China, enrolled in the study during January 1, 1986, through September 30, 1989, and actively followed via annual visits.

RESULTS

By September 30, 1993, 852 deaths and 554 incident cancer cases were identified during the follow-up period, which averaged 5.4 years per subject. The overall incidence rate for cancer was 568 per 100 000 man-years, with the 3 leading sites being lung (146/100 000), stomach (116/100 000), and liver (81/100 000). Forty-one percent of all deaths were from cancer. Stroke was the most frequent cause of death unrelated to cancer, with an age-adjusted rate 4.2 times higher than that of US white men (201/100 000 vs 48/100 000), followed by ischemic heart disease, with an age-adjusted rate one-fifth that of US white men (69/100 000 vs 366/100 000). Compared with lifelong nonsmokers, the relative risks in heavy smokers (20 or more cigarettes per day) after adjustment for alcohol consumption were 2.2 for any incident cancer, 9.4 for incident lung cancer, 6.7 for head and neck cancer, and 1.8 for liver cancer. In terms of mortality, heavy smokers were at a 60% greater risk of death relative to lifelong nonsmokers; there was a 2.3-fold excess risk of death from cancer and 2-fold to 3-fold excess risk of death from heart disease.

CONCLUSIONS

Cigarette smoking is an important predictor of risk of cancer and mortality in men in Shanghai. Among the study subjects, 36% of all cases of cancer and 21% of all deaths could be attributed to cigarette smoking.