ANI, Aug 4, 2010, 12.01pm IST
The study results were based on data from the Black Women’s Health Study (BWHS), a large follow-up study of 59,000 African American women from across the U.S. conducted by investigators at the Slone Epidemiology Center since 1995.
Researchers from the Slone Epidemiology Center at Boston University School of Medicine (BUSM) followed 53,848 participants in the BWHS for 12 years, during which time 789 cases of breast cancer developed on which information on receptor status was obtained.
The incidence of estrogen receptor negative cancer was 65 per cent greater among women who had ever used oral contraceptives than among nonusers.
Estrogen receptor positive tumors have a better prognosis than estrogen receptor negative breast cancers.
Lead author Lynn Rosenberg, an associate director of the Slone Epidemiology Center and professor of epidemiology at BUSM, pointed out- that oral contraceptive formulations have changed over time, making it relevant to assess the effects of more recent formulations on breast cancer risk.