Patients with breast cancer who have dense breast tissue may have a significantly increased risk for developing cancer in their other breast, according to a retrospective, case-controlled study published in Cancer.
“A big challenge in the management of breast cancer survivors is trying to counsel women appropriately on their risk for developing a second breast cancer in the contralateral side,” Carlos H. Barcenas, MD, MS, assistant professor of breast medical oncology at The University of Texas MD Anderson Cancer Center, told HemOnc Today. “There are a number of well-established risk factors for developing both primary and secondary breast cancers, such as BRCA mutations, family history and tumor’s ER status. We also know that breast density is a risk factor for the development of primary breast cancer. However, no one had looked closely at breast density as a risk factor for developing a second contralateral breast cancer.”
Due in large part to the variability of risk factors in patients, the 10-year risk for women with breast cancer developing contralateral breast cancer (CBC) can range from 2% to 40%, Isabelle Bedrosian, MD, associate professor of breast surgical oncology at The University of Texas MD Anderson Cancer Center, said in a press release.
In their study, Barcenas, Bedrosian and colleagues identified 680 women with stage I, II and III breast cancer treated at MD Anderson between 1997 and 2012. Women with BRCA mutations were excluded from the study because of their known increased risk for CBC.
Women diagnosed with cancer in the opposite breast more than 6 months after initial breast cancer diagnosis (n = 229) were compared with women who had not developed CBC (n = 451). Among women with CBC, 33.9% had nondense breast tissue, compared with 60.7% who had dense breast tissue. Among women without CBC, 48.3% had nondense breast tissue and 51.7% had dense breast tissue.
After adjusting for potential prognostic risk factors for breast cancer, the odds of developing CBC appeared significantly higher for women with dense breasts than for women with nondense breasts (OR = 1.8; 95% CI, 1.22-2.64).
“After adjusting for known breast cancer risk factors, we found almost a twofold increased risk for developing contralateral breast cancer in those survivors with dense breasts,” Barcenas said. “It was somewhat surprising to uncover such a significant association of dense breast and the risk for developing a contralateral breast cancer.”
Additionally, women who received chemotherapy or endocrine therapy were less likely to develop cancer in the other breast, findings consistent with previous studies that showed a 35% to 40% reduction in the risk for developing CBC in women who were first treated with chemotherapy or endocrine therapy.
“Our findings have valuable implications for both newly diagnosed patients with dense breasts and in breast cancer survivors as we manage their long-term risk for a secondary breast cancer,” Barcenas said. “Our future goal is to develop a risk model incorporating breast density to best assess a breast cancer survivor’s risk for developing contralateral breast cancer. One potential implication of these findings could be in the decision of which breast imaging surveillance method to use in breast cancer survivors who have dense breasts.”
Researchers noted the small size of participants as a limitation.
“In the long-term, we hope to move this research forward and use a risk model tool to counsel patients on their personal risk and their options of treatment and surveillance,” Barcenas said. “That could be, for example, to use an MRI for breast imaging surveillance in breast cancer survivors, if their risk is sufficiently high.” – by Chuck Gormley
For more information:
, MS, can be reached at Department of Medical Oncology, Unit 1354, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030; email: firstname.lastname@example.org.
The University of Texas MD Anderson Cancer Center Young Breast Cancer Survivors Program funded this study. The researchers report no relevant financial disclosures.