Breast Cancer Risk Factors: Lesbian and Heterosexual Women

Institution: University of California, San Francisco
Investigator(s): Suzanne  Dibble , D.N.Sc., RN - Stephanie  Roberts , M.D. -
Award Cycle: 1998 (Cycle IV) Grant #: 4BB-1501 Award: $186,214
Award Type: CRC Full Research Award
Research Priorities
Etiology>Environment and gene/environment interactions: nature vs. nurture

This is a collaboration with: 4BB-1500 -

Initial Award Abstract (1998)
Some scientists have looked at the risk factors for breast cancer and the little that is known about lesbians and speculated that the risk for developing breast cancer may be two to three times higher for lesbians than for heterosexual women. But no scientific studies have been published on this issue. We have just finished a small study comparing information contained in the medical records of lesbian and heterosexual women and have found some differences in the distribution of some breast cancer risk factors. We need to do a larger study because some of the established risk factors for developing breast cancer are not collected in medical records. Also, the women whose records we studied attended a clinic that mostly serves young, urban, poor women. Therefore, we would like to compare a larger group of women from throughout California who are of different sexual orientations, living situations, and incomes to explore the distribution of risk factors for breast cancer.

The research question that we would like to answer is: Are the distributions of the standard risk factors for developing breast cancer different for women who call themselves lesbians in contrast with their heterosexual sisters or heterosexual female friends? We will ask lesbians throughout California to complete an anonymous survey. The lesbians will be asked to give the same survey to a sister (if she has one) and a heterosexual female friend. Then we will compare the differences between them. Lesbians will be recruited through articles, flyers, advertisements, a toll-free telephone number, clinics like Lyon-Martin Women's Health Services that specialize in serving lesbians, and through doctors who are members of the Gay and Lesbian Medical Association. We will use special techniques to be sure that we get a variety of women who represent the mix of lesbians living in California, and that help reach women who are not public about being lesbian.

If we find in this larger study that the lesbians have a different distribution of risk factors for developing breast cancer than their heterosexual sisters and friends, then lesbians and their health care providers need to know this. More studies can then be done to see if these risk factors can be modified or if lesbians need to have more frequent breast exams, mammograms, or biopsies than do heterosexual women.


Final Report (2002)
Scientists have explored the risk factors for the development of breast cancer with the small amount of information that is "known" about Lesbians and proposed that the risk of developing breast cancer may be two to three times higher for lesbians than for heterosexual women. The purpose of this project was to determine whether lesbians have a higher risk profile for the development of breast cancer compared to heterosexual women. We distributed surveys to lesbians, age 40 and older throughout the state of California. Additionally, we asked each lesbian participant to have a heterosexual female friend who lives in California and a sister (if they have one) closest in age to fill out an identical survey. A total of 765 women (255 groups) contributed data to the triad analysis. There were no significant differences in age, ethnicity, employment status, or insurance status among the three groups.

Lesbians had significantly more education than either their friends (p<.001) or sisters (p<.001) Lesbians were more likely to live in urban areas (50%) than their sisters (31 %, p<.001). Lesbians had significantly (p<.02) less live births, miscarriages, and abortions when compared to their sisters and friends. Lesbians used birth control pills significantly less when compared to their sisters (p<.001) and friends (p<.001). There were no significant differences in current alcohol use between lesbians when compared to their sisters or friends, however lesbians reported significantly more problems with alcohol than either their friends (p<.001) or sisters (p=.001).

Lesbians currently smoked significantly less than their sisters (p= .014) but had a history of smoking more when compared to their friends (p= .016) or their sisters (p= .023).

Lesbians had a significantly higher BMI (weight to height ratio) than their friends (p= .009) or their sisters (P= .009). There were no significant differences in weekly exercise, being a vegetarian, or eating a low-fat diet among the groups. There were no significant differences in breast self exam rates or clinical breast examination rates among the groups. Lesbians had statistically significant more breast biopsies than their friends (P=.006) and more biopsies (p=.003) and mammograms (p=.005} than their sisters. There was a trend that the lesbians had more diagnoses of breast cancer (7.8%) than their friends (3.9%, p<.08). When the sisters (n=324) were compared using the Gail Risk Model, the lesbians had a significantly higher 5 year (1.2 vs. 1.1; p<.001) and lifetime risk for developing breast cancer (11.1 vs. 10.6; p=.011).

In summary, lesbians may have a higher risk profile for developing breast cancer based on this sample; but it is by no means two or three times higher than for heterosexual women.
Differences in Risk Factors for Breast Cancer: Lesbian & Heterosexual Women
Periodical:Journal of Gay and Lesbian Medical Association
Index Medicus:
Authors: Roberts, S., Dibble, S., Scanlon, J., Paul, S., & Davids, H.
Yr: 1998 Vol: 2 Nbr: 3 Abs: Pg:93-101