Roland L. Phillips

Dietary and lifestyle characteristics were evaluated in relation to subsequent prostatic cancer risk in a cohort of approximately 14,000 Seventh-day Adventist men who completed a detailed lifestyle questionnaire in 1976 and who were monitored for cancer incidence until the end of 1982. During the 6-year follow-up period, 180 histologically confirmed prostatic cancers were detected among some 78,000 man-years of follow-up. Increasing educational attainment was associated with significantly decreased risk of prostate cancer in this study; age at first marriage was also inversely associated with risk, although this was not significant. There was no relationship between body mass index (as measured by Quetelet's Index) and risk. A history of prostate "trouble" was associated with a 60% increase in risk which was highly significant. Although there were suggestive relationships between increasing animal product consumption and increased risk, these results did not persist after accounting for the influence of fruit and vegetable consumption. Nor was exposure to the vegetarian lifestyle during the childhood years associated with alterations in subsequent risk. However, increasing consumption of beans, lentils and peas, tomatoes, raisin, dates, and other dried fruit were all associated with significantly decreased prostate cancer risk.

The Seventh-Day Adventist population abstains from smoking and drinking; about 50% follow a lacto-ovo-vegetarian diet; and most avoid the use of coffee, tea, hot condiments, and spices. Existing data on cancer mortality in Seventh-Day Adventists clearly document mortality rates that are 50 to 70% of general population rates for most cancer sites that are unrelated to smoking and drinking. Several approaches to determining whether this reduced risk is due to the unique Seventh-Day Adventist life-style or selective factors related to who choses to become and remain a Seventh-Day Adventist are described. A comparison of the mortality experience of Seventh-Day Adventist and non-Seventh-Day Adventist physicians shows equal cancer mortality, which is consistent with the hypothesis that the apparent reduced risk of cancer death in all Adventists may be due to selective factors. However, the results of a small case-control study of colon and breast cancer among Adventists show statistically significant relative risks for colon cancer of 2.8 for past use of meat. For current food use, the significant relative risks are 2.3 for beef, 2.7 for lamb, and 2.1 for a combined group og highly saturated fat foods. This strongly suggests that the lacto-ovo-vegetarian diet may protect against colon cancer. However, the evidence linking diet to breast cancer is less clear. Because of the marked variability in dietary habits within the Seventh-Day Adventist population, they will be a productive group for further study of diet and cancer.

Epidemiologic studies of diet and pancreas cancer are few, and include ecologic comparisons and a limited number of prospective and case-control studies. Foods and/or nutrients that have been suggested to be associated with increased risk of this cancer include total fat intake, eggs, animal protein, sugar, meat, coffee and butter. Consumption of raw fruits and vegetables has been consistently associated with decreased risk. Dietary habits and medical history variables were evaluated in a prospective study of fatal pancreas cancer among 34,000 California Seventh-day Adventists between 1976 and 1983. Forty deaths from pancreas cancer occurred during the follow-up period. Compared to all US whites, Adventists experienced decreased risk from pancreas cancer death (standardized mortality ratio [SMR] = 72 for men; 90 for women), which was not statistically significant. Although there was a suggestive relationship between increasing meat, egg, and coffee consumption and increased pancreatic cancer risk, these variables were not significantly related to risk after controlling for cigarette smoking. However, increasing consumption of vegetarian protein products, beans, lentils, and peas as well as dried fruit was associated with highly significant protective relationships to pancreas cancer risk. A prior history of diabetes was associated with increased risk of subsequent fatal pancreas cancer, as was a history of surgery for peptic or duodenal ulcer. A history of tonsillectomy was associated with a slight, nonsignificant protective relationship as was history of various allergic reactions. These findings suggest that the protective relationships associated with frequent consumption of vegetables and fruits high in protease-inhibitor content are more important than any increase in pancreas cancer risk attendant on frequent consumption of meat or other animal products. Furthermore, the previously reported positive associations between diabetes and abdominal surgery and pancreas cancer risk are supported in these data.

In previous reports concerning cancer among Seventh-Day Adventists (SDA), comparisons were made only with the general population. This report compared California SDA to a sample of non-SDA who were demographically similar to SDA. The study consisted of 17 years of follow-up (1960--76) on 22,940 white California SDA and 13 years of follow-up (1960--72) on 112,725 white California non-SDA. Both groups completed the same base-line questionnaire in 1960. Deaths were ascertained by annual contacts with each study member and by computer-assisted record linkage with the California State death certificate file. Results indicated that, with the exception of colon-rectal cancer and smoking-related cancers, the difference in risk of fatal cancer between SDA and non-SDA was substantially reduced when SDA were compared with a more socioeconomically similar population. The persistence of the low risk for colon-rectal cancer can probably be attributed to some aspect of the diet or life-style of the SDA.