A prospective study of induced abortion and breast cancer in African-American women.
OBJECTIVE
There continues to be controversy about whether induced abortion influences the risk of breast cancer. Because case-control studies of this relation are subject to recall bias, there is a need for prospective data. Further, there has been little study of abortion and breast cancer in African-American women. We assessed the relation of abortion to risk of breast cancer in a prospective follow-up study of African-American women.


METHODS
Black Women's Health Study participants have been followed by mailed questionnaires every two years since enrollment in 1995. Participants reported 348 incident breast cancers during 205,983 person-years of follow-up. Women who had an induced abortion were compared with women who had never had one, with nulliparous and parous women analyzed separately. Incidence rate ratios (IRR) with two-sided 95% confidence intervals (CI) were derived from Cox regression models that controlled for age, age at first birth, number of births, history of spontaneous abortion, and other factors.


RESULTS
Among nulliparous women, the IRR for any induced abortion relative to none was 0.9 (95% CI = 0.5-1.4), and among parous women, the comparable IRR was 1.1 (95% CI = 0.8-1.4). Risk did not vary by number of abortions, age at first abortion, age at diagnosis or a family history of breast cancer in either nulliparous or parous women.


CONCLUSIONS
Our findings indicate that induced abortion does not increase breast cancer risk in African-American women.
Palmer
Julie R
JR
Slone Epidemiology Center, Boston University School of Public Health, 1010 Commonwealth Avenue, Boston, MA 02215, USA. jpalmer@slone.bu.edu
Wise
Lauren A
LA
Adams-Campbell
Lucile L
LL
Rosenberg
Lynn
L
D000028:Abortion, Induced / Q000009:adverse effects* / Q000706:statistics & numerical data; D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000368:Aged; D001943:Breast Neoplasms / Q000208:ethnology / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D015999:Multivariate Analysis; D010298:Parity; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology