Studies that relate to population-based data on cancer prevalance and incidence
The Women's Health Trial Vanguard Study was conducted to examine the feasibility of a nationwide, randomized multicenter intervention trial to test the hypothesis that a low-fat diet followed for a period of 10 years will reduce breast cancer risk. Women ages 45-69 years at increased risk of breast cancer were randomized into intervention (low-fat diet, n = 184) and control (usual diet, n = 119) groups. On the basis of 4-day food records, baseline fat intakes were comparable in the two groups, averaging 1,718 kcal with 39% of energy as fat.
A 5.5-fold range in breast cancer incidence rates in 21 countries shows strong correlation with national estimates of per capita intake of dietary fat, but not with other caloric sources (proteins and carbohydrates). It is argued that certain breast cancer and hormone factors may contribute little to the explanation of such international variations in incidence of this neoplasm.
Current awareness of the importance of environmental factors such as diet in the etiology of human cancer has stimulated renewed interest in animal models for studying effects of diet on tumorigenesis. Diet can influence cancer in animals by affecting the initiation or subsequent preneoplastic stage of tumorigenesis, but it has less effect on tumor growth. Caloric restriction has a general inhibitory influence on tumorigenesis. Dietary fat, on the other hand, tends to promote tumorigenesis, but only certain types of tumors, such as mammary tumors, are affected.
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.
Some data, including our findings from the Health Professionals Follow-Up Study (HPFS) from 1986 through January 31, 1992, suggest that frequent intake of tomato products or lycopene, a carotenoid from tomatoes, is associated with reduced risk of prostate cancer. Overall, however, the data are inconclusive. We evaluated additional data from the HPFS to determine if the association would persist.
Several human studies have observed a direct association between retinol (vitamin A) intake and risk of prostate cancer; other studies have found either an inverse association or no association of intake of beta-carotene (the major provitamin A) with risk of prostate cancer. Data regarding carotenoids other than beta-carotene in relation to prostate cancer risk are sparse.
We concluded a prospective cohort study to examine the relationship between the intake of various carotenoids, retinol, fruits, and vegetables and the risk of prostate cancer.
Mean serum insulin-like growth factor-I was 9% lower in 233 vegan men than in 226 meat-eaters and 237 vegetarians (P = 0.002).
The articles included in this library are original, peer-reviewed research papers, also known as "primary sources". Peer-reviewed papers are those published in journals who use a committee of other scientists to carefully review the author's study methods, analysis, and conclusions, and to provide feedback for improvements before publication. The result are papers whose authors who are rigorously held accountable for their statements. Click here for a list of inclusion criteria.
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