LOS ANGELES, CALIFORNIA – A new study by researchers at UCLA says that gay or bisexual women who cohabit with their same-sex partners may be at greater risk for developing fatal breast cancer. The study, published this spring in the Journal of Women’s Health, found that women partnered in same-sex couples were more than three times at risk as those in different sex relationships.

This year, more than 220,000 U.S. women will be diagnosed with breast cancer, and the disease will kill about 37,000, according to the National Cancer Institute. The study analyzed data from 136,865 gay or bisexual women, aged 18 to 80. The researchers, led by Susan D. Cochran and Vickie M. Mays, found that lesbians and bisexual women are more likely than other women to have more risk factors for breast cancer. Gay women are less likely to seek routine health screenings, such as mammograms, professional breast exams, and breast self-exams. They are also less likely to give birth by age 30, which increases risk of breast cancer.