Oral contraceptive use and estrogen/progesterone receptor-negative breast cancer among African American women.
BACKGROUND
Oral contraceptive formulations have changed over time, making it relevant to assess the effect of more recent formulations on breast cancer risk. In addition, some studies have found stronger positive associations of oral contraceptive use with estrogen receptor-negative (ER(-)) than with ER-positive (ER(+)) breast cancer. We carried out the first assessment of the effect of oral contraceptive use on the incidence of breast cancer classified by receptor status among African American women, a group disproportionately affected by ER(-) cancer.


METHODS
We followed 53,848 Black Women's Health Study participants from 1995 to 2007 through biennial health questionnaires, in which participants reported information about incident breast cancer, oral contraceptive use, and breast cancer risk factors. Pathology information was obtained on receptor status for 789 incident cases. Incidence rate ratios (IRR) with 95% confidence intervals (95% CI) were derived from Cox regression models with control for confounding factors.


RESULTS
Ever use of oral contraceptives was more strongly associated with ER(-)PR(-) breast cancer (279 cases; IRR, 1.65; 95% CI, 1.19-2.30) than with ER(+)PR(+) cancer (386 cases; IRR, 1.11; 95% CI, 0.86-1.42). The risk of ER(-)PR(-) breast cancer increased with increasing duration of use among recent users.


CONCLUSIONS
These results indicate that the oral contraceptive formulations used in recent decades increase breast cancer risk in African American women, with a greater effect for ER(-) than ER(+) cancer.


CONCLUSIONS
Mechanisms to explain the adverse influence of oral contraceptive use on ER(-) breast cancer need to be elucidated.
Rosenberg
Lynn
L
Slone Epidemiology Center at Boston University, 1010 Commonwealth Avenue, Boston, MA 02215, USA. lrosenbe@bu.edu
Boggs
Deborah A
DA
Wise
Lauren A
LA
Adams-Campbell
Lucile L
LL
Palmer
Julie R
JR
D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D001943:Breast Neoplasms / Q000208:ethnology* / Q000378:metabolism; D002626:Chemistry, Pharmaceutical; D003276:Contraceptives, Oral / Q000008:administration & dosage* / Q000737:chemistry; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D008875:Middle Aged; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult
D003276:Contraceptives, Oral; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone