Oral contraceptives and the risk of ductal breast carcinoma in situ.

UNLABELLED: Recent evidence suggests that oral contraceptive use is associated with little to no increased risk of invasive breast carcinoma. No study has examined the relationship between oral contraceptive use and the risk of non-invasive breast carcinoma, that is, breast carcinoma in situ.

OBJECTIVE

To define the role of oral contraceptive use in the development of breast carcinoma in situ.

METHODS

The data are 875 ductal carcinoma in situ (DCIS) cases diagnosed among residents of the state of Connecticut from September 15, 1994 to March 14, 1998 and between the age of 20 and 79 years as well as 999 control subjects. Controls are female Connecticut residents collected via random-digit-dial and frequency matched to the cases by 5-year age intervals. Telephone interviews were used to collect information on risk factors and cancer screening history. Logistic regression was used to provide maximum likelihood estimates of the odds ratios (OR) with 95% confidence intervals (95% CI).

RESULTS

The risk of being diagnosed with DCIS for women who had ever used oral contraceptives was not increased relative to women who had never used them (OR: 1.0, 95% CI: 0.8, 1.2). The risk did not significantly increase with duration of oral contraceptive use, nor with duration of high estrogen use, time since last use, progestin or estrogen type, or age at first use. Furthermore, the association between oral contraceptive use and DCIS risk did not vary by the presence of a family history of breast cancer or by menopausal status.

CONCLUSIONS

In these data, no evidence was found for an increased risk of ductal carcinoma in situ associated with the use of oral contraceptives.