267705 Pregnancy weight gain may protect against breast cancer in women with polycystic ovarian syndrome: Prospective evidence from the Child Health and Development Studies pregnancy cohort

Monday, October 29, 2012

Piera M. Cirillo, MPH , Child Health and Development Services, Public Health Institute, Berkeley, CA
Erica Wang, MD MAS , Reproductive Endocrinology & Infertility, UCSF Center for Reproductive Health, San Francisco, CA
Roberta Christianson, MS , Child Health and Development Studies, Public Health Institute, Berkeley, CA
Marcelle I. Cedars, MD , Director, Division of Reproductive Endocrinology and Infertility, UCSF Center for Reproductive Health, San Francisco, CA
Barbara Cohn, PhD , Director, Child Health and Development Studies, Public Health Institute, Berkeley, CA
Polycystic ovarian syndrome (PCOS) could modify the impact of pregnancy on risk of breast cancer. PCOS is characterized by irregular menstrual cycles evident in early life and comprise a subgroup where early intervention is possible. Although some women with PCOS are infertile, the majority achieve pregnancy. Here we examine whether PCOS modifies the known association between greater pregnancy weight gain and breast cancer in a prospective pregnancy cohort, The Child Health and Development Studies.

Subjects were Caucasians with single liveborns (N=9,387). Menstrual irregularity, cycles >35 days or anovulation was identified in 13% as a proxy for PCOS. Linkage to the California Cancer Registry identified 201 breast cancer cases diagnosed by age 54.

Greater pregnancy weight gain predicted increased breast cancer risk in women with regular cycles, but not among women with PCOS (p <0.01 for interaction). Women with PCOS who gained at least 16 lbs (lowest quartile) had a 50 percent reduction in breast cancer risk (95% CI = 0.27,0.99) regardless of baseline weight. To investigate this surprising finding we examined the relation of PCOS and weight gain to third trimester serum testosterone (T) and sex hormone binding globulin (SHBG). Greater weight gain predicted higher T and lower SHBG only among women with PCOS (p <0.05 for each interaction), consistent with higher levels of bioavailable testosterone, a possible protective mechanism. Findings show consequences of pregnancy weight gain are complex. Women with PCOS and low pregnancy weight gain may be a target for early breast cancer screening and intervention.

Learning Areas:
Basic medical science applied in public health
Clinical medicine applied in public health

Learning Objectives:
Demonstrate the effects of pregnancy weight gain on the risk of breast cancer in a prospective cohort. Evaluate the impact of irregular menstrual cycle status, a proxy for polycystic ovary syndrome (PCOS), on the pregnancy weight gain association with breast cancer. Discuss possible mechanisms to explain the different associations for women with irregular vs. regular menstrual cycles.

Keywords: Breast Cancer, Women's Health

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am a research scientist with the Public Health Institute, who has worked on the Child Health and Development Studies cohort for more than 20 years, mentored by the director and the CHDS bio-statisticians over the span of many research projects.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.