TITLE: A population-based case-control study of diet and breast cancer in Australia.

AUTHORS: Rohan TE; McMichael AJ; Baghurst PA

AUTHOR AFFILIATION: CSIRO Division of Human Nutrition, Adelaide, Australia.

SOURCE: Am J Epidemiol 1988 Sep;128(3):478-89

CITATION IDS: PMID: 3414656 UI: 88324377

NOTE FROM THE COALITION: This 1988 study, which was conducted on Australian women, revealed the reluctance of researchers to publish data showing the association between induced abortion and breast cancer. Abortion-breast cancer data obtained by the Rohan researchers were not published with the rest of the data in the American Journal of Epidemiology and were withheld for seven years, in spite of the fact that induced abortion was found to be the strongest risk factor found. The data were not published until Nadine Andrieu's 1995 meta-analysis of six studies examining the synergistic effect between family history and induced abortion came out in France. This was the first time that the abortion-breast cancer data in the Rohan study was ever published, and it revealed a 160% increased risk of breast cancer among Australian women who had had induced abortion. It was the only variable in the Rohan study which was statistically significant, even surpassing family history in increased risk. Spontaneous abortion was not linked with breast cancer.

ABSTRACT: The relation between diet and breast cancer was examined in a population-based case-control study conducted in Adelaide, South Australia, involving 451 case-control pairs aged 20-74 years. Cases were identified through the state cancer registry between April 1982 and July 1984; for each case, one age-matched control was selected from the electoral register.

Dietary intake was measured by self-administered quantitative food frequency questionnaires. There was little variation in risk across levels of daily intake of energy, protein, and total fat; for energy, the relative risk of breast cancer at the uppermost fifth of intake, relative to a risk of unity for the lowest fifth, was 1.22 (95% confidence interval (CI) 0.80-1.86); for protein, the corresponding relative risk was 1.09 (95% CI 0.72-1.64), and for total fat, the relative risk was 0.90 (95% CI 0.59-1.38). Variation in risk in association with sugar and starch intake was also insubstantial, while for fiber, there was a nonuniform reduction in risk at the three uppermost fifths of intake. Risk varied little with level of retinol intake, but it decreased with increasing intake of beta-carotene, a trend that was statistically significant; the relative risk of breast cancer at the uppermost fifth of beta-carotene intake was 0.76 (95% CI 0.50-1.18). Multivariate adjustment for the effects of potentially confounding variables did not alter these patterns. The study does not support a role for dietary fat in the etiology of breast cancer.