No abstract

Intake of dietary provitamin A (carotene) was inversely related to the 19-year incidence of lung cancer in a prospective epidemiological study of 1954 middle-aged men. The relative risks of lung cancer in the first (lowest) to fourth quartiles of the distribution of carotene intake were respectively, 7.0, 5.5, 3.0, and 1.0 for all men in the study, and 8.1, 5.6, 3.9, and 1.0 for men who had smoked cigarettes for 30 or more years. Intake of preformed vitamin A (retinol) and intake of other nutrients were not significantly related to the risk of lung cancer. Neither carotene nor retinol intake was significantly related to the risk of other carcinomas grouped together, although for men in whom epidermoid carcinomas of the head and neck subsequently developed, carotene intake tended to be below average. These results support the hypothesis that dietary beta-carotene decreased the risk of lung cancer. However, cigarette smoking also increases the risk of serious diseases other than lung cancer, and there is no evidence that dietary carotenoids affect these other risks in any way.

A positive association between elevated blood pressure and risk of death from cancer has been observed in four long-term prospective studies. In the Western Electric Health Study, the relationship was specific to death from renal cell carcinomas and epidermoid cancers of the head and neck. The relationship with epidermoid head and neck cancer was indirect, resulting from the effects of alcohol consumption on both blood pressure and on risk of this cancer. The relationship with kidney cancer was probably due to effects of abnormal renal cell activity. The association between blood pressure and cancer mortality at other sites was not significant.