RECALL BIAS IN THE ASSOCIATION OF MICRONUTRIENT INTAKE AND BREAST-CANCER

A nested case-control study within the Canadian National Breast Screen ing Study was conducted to examine whether there was evidence for reca ll bias in the reporting of past micronutrient intake. Dietary data co llected upon enrollment between 1982 and 1985 from 325 breast cancer c ases and 628 matched controls were compared with data collected in 198 8 after disease diagnosis. The retrospective estimates of mean micronu trient intakes from food sources were found to be very similar to the prospective estimates for cases and controls. Errors of omission and c ommission for the reporting of previous supplementary vitamin use were identical for both subject groups. The odds ratios estimated for the association of micronutrient intake and breast cancer for the prospect ive and retrospective data were similar in magnitude and the 95% confi dence intervals overlapped considerably. There was no evidence for rec all bias in the estimation of past micronutrient intake by breast canc er cases as compared to controls.