Your search found 1 Results
AMERICAN JOURNAL OF EPIDEMIOLOGY. 1994 Nov 15; 140(10):956.A paper by Nischan and colleagues, "Comparison of Recalled and Validated Oral Contraceptive Histories," which examines the accuracy of the histories of oral contraceptive use (defined as agreement with gynecologists' records concerning duration of use, times since first and last use, and individual preparations used) in a WHO case-control study of breast cancer, "WHO Collaborative Study of Neoplasia and Steroid Contraceptives," fails to comment on the more frequent validity of the histories among those persons with breast cancer. Of 253 contraceptive histories from persons with breast cancer, for whom responses from at least 1 gynecologist were available, 234 (92.4%) were confirmed; of those from 621 controls, 524 were. The difference is statistically significant (chi-square test, p < 0.01). This better recall of ever-use of oral contraceptives among breast cancer patients creates a bias that makes an association between breast cancer and ever-use of oral contraceptives stronger than it is. The slight elevation in breast cancer risk associated with ever-use of oral contraceptives found in the WHO study may be due to this. There is no information about the accuracy of negative oral contraceptive histories.