An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates.
BACKGROUND
The role of diet in the etiology of breast carcinoma has been debated for decades. The ecologic approach generally finds that dietary fat is highly associated with breast carcinoma mortality, with fish intake and solar ultraviolet-B (UV-B) radiation, a source of vitamin D, inversely associated. Case-control and cohort studies generally find a variety of chemical, nonfat dietary, environmental, genetic, lifestyle, and reproductive factors to be important.


METHODS
An ecologic study was conducted using breast carcinoma mortality rates (1989-1996), dietary supply data, and latitude (an index of solar UV-B radiation) from 35 countries.


RESULTS
The fraction of energy derived from animal products (risk) combined with that from vegetable products (risk reduction), followed by solar UV-B radiation and, to a lesser extent, energy derived from alcohol (risk) and fish intake (risk reduction), were found to explain 80% of the variance of breast carcinoma mortality rates. Dietary fat contributed insignificantly in regressions involving the other factors.


CONCLUSIONS
It is hypothesized that animal products are associated with risk for breast carcinoma because they are associated with greater amounts of insulin-like growth factor-1 and lifetime doses of estrogen. Vegetable products contain several risk reduction components including antioxidants and phytoestrogens. The association with latitude is very likely because of solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts. Fish intake is associated with risk reduction through vitamin D and n-3 oils. These results are consistent with those of many case-control and cohort studies but should be assessed in well designed cohort studies.
Grant
William B
WB
Newport News, Virginia, USA. wbgrant@infi.net
D000428:Alcohol Drinking; D000975:Antioxidants; D001943:Breast Neoplasms / Q000453:epidemiology / Q000401:mortality*; D004032:Diet; D004463:Ecology; D004781:Environmental Exposure; D004967:Estrogens; D004968:Estrogens, Non-Steroidal; D014943:Global Health; D006801:Humans; D007334:Insulin-Like Growth Factor I; D007529:Isoflavones; D016014:Linear Models; D008460:Meat; D048789:Phytoestrogens; D028321:Plant Preparations; D012307:Risk Factors; D017747:Seafood; D014466:Ultraviolet Rays; D014675:Vegetables
D000975:Antioxidants; D004967:Estrogens; D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D007334:Insulin-Like Growth Factor I