DIETARY FACTORS AND 2ND PRIMARY CANCERS - A FOLLOW-UP OF ORAL AND PHARYNGEAL CANCER-PATIENTS

To investigate the possible relationship between dietary factors and t he development of multiple primary cancer, a nested case-control study was carried out within a cohort of 1,090 oral and pharyngeal cancer p atients. This patient group, enrolled in 1984-1985 in a population-bas ed case-control study conducted in four areas of the United States, wa s followed up through June 1989 for the occurrence of second primary c ancer. Information on a number of risk factors, including diet, ascert ained from interviews conducted at baseline (1984-1985) and at follow- up were compared between 80 patients with histologically confirmed sec ond primary cancers (39% in the upper aerodigestive tract, 32% in the lung 29% elsewhere) and 189 sex- and survival matched control patients free of second cancers. Although few significant trends emerged, the results were suggestive of a protective effect provided by higher inta ke of vegetables. Risk of second primary cancers was 40-60% lower amon g those with the highest levels of intake for total vegetables and mos t vegetable subgroups, including dark yellow, cruciferous, and green l eafy vegetables and legumes. Risks were also nonsignificantly lower am ong those with high consumption of vitamin C and carotenoids, with the adverse effects of alcohol being most evident among heavy drinkers wi th low vitamin Cor carotenoid intake. There was also some evidence of an interaction between smoking and vitamin C consumption, but numbers of nonsmokers were small. Among other dietary factors considered, posi tive associations were found with increasing consumption of meats, liv er, and retinol. The findings suggest that dietary factors contribute along with alcohol and smoking to the excess risks of second primary c ancers among patients with oral and pharyngeal cancers.