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Triple-Negative Breast Cancer Risk Factors

Minority Women and BRCA1 Carriers Are At High Risk

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Updated April 10, 2009

Triple-negative breast cancer (TNBC) tests negative for estrogen, progesterone, and HER2 receptors. Although TNBC responds to chemotherapy treatments, there have not been effective targeted treatments for this aggressive type of breast cancer. Diagnosis is usually made at a late stage, has shorter survival rates, and has a high rate of relapse 5 years after treatment. Researchers are working on targeted therapies to treat this disease, but women who are at high risk should be proactive in monitoring their own health, because early detection could help boost survival rates.

African American Women Are At Highest Risk For TNBC

In a study of invasive breast cancer patients done at M. D. Anderson Cancer Center between 2001 and 2006,18.9% of those patients were diagnosed with triple-negative breast cancer. Within the group of women who had TNBC, Asian women had the lowest risk, Caucasians and Latinas had a moderate risk, and African Americans had triple the average risk. African Americans and Latinas have low risk of developing breast cancer, but when they are diagnosed, they tend to have triple-negative breast cancer. Survival rates for African Americans are not good, as only 14% of patients are still alive five years after diagnosis. But for TNBC patients who survive from 7 to 10 years beyond treatment, rates of recurrence are low.

Age and Socioeconomic Status

African Americans under 40 who are living at low socioeconomic status have the highest risk for a diagnosis of TNBC. But young Latinas living at or near the poverty level had the second-highest risk. It is still being studied, but researchers think that genetics, lack of health education, and inadequate access to medical care may be related to the disproportionate number diagnoses in low-income minority women. Ongoing stress and social isolation, due to life in areas with high crime may also contribute to development of some types breast cancer.

Genetic Risk Linked with TNBC

Having the BRCA1 mutation raises a woman's risk for triple-negative breast cancer. In a study of women with triple-negative breast cancer, it was discovered that 90% of TNBC patients had the BRCA1 mutation. Fewer than 10% of patients in this study had the BRCA2 mutation. Research on the link between genetic mutations and triple-negative breast cancer is still going on, but the early studies strongly suggest that having the BRCA1 mutation does increase the risk for developing this type of breast cancer.

Effects of Pregnancy and Breastfeeding on TNBC Risk

It's too early to know for sure, but scientists think that there may be some relationship between a woman's number of full-term pregnancies, the amount of time she spends breastfeeding, and her risk for developing TNBC. For Latinas, 3 or more full-term pregnancies and a shorter period of breastfeeding may relate to an increased risk. For African American and Asian women, number of pregnancies and breastfeeding time appears to have no relation to increased risk.

High-Risk Women Should Be Vigilant About Breast Health

Dr. Olufunmilayo Olopade, who is doing research on triple-negative breast cancer patients in Chicago and Nigeria says, "Women with triple negative breast cancer need to know that a diagnosis is not a death sentence. It's aggressive but can be treated. The earlier the detection, the better." The standard guidelines for starting mammograms at age 40 are not helping women at risk for TNBC. "If you're at risk," Olopade says, "you don't want to wait until you're 40 to be screened." Women should start doing a monthly breast self-exam at age 20, and have annual clinical breast exams. If you are under 40, find a breast lump and suspect you may be at high risk, talk to your doctor about having a breast ultrasound or a mammogram.

Sources:

Association of triple-negative breast cancer phenotype with parity and breastfeeding duration. S. S. Shinde, M. R. Forman, H. M. Kuerer, K. K. Hunt, L. Pusztai, W. F. Symmans. ASCO 2008 Breast Cancer Symposium, Abstract No: 77.

Descriptive Analysis of Estrogen Receptor (ER)-Negative, Progesterone Receptor (PR)-Negative, and HER2-Negative Invasive Breast Cancer, the So-called Triple-Negative Phenotype: A Population-Based Study From the California Cancer Registry," KR Bauer, M Brown, RD Cress, CA Parise, V Caggiano, CANCER, May 1, 2007.

Parity and breastfeeding are protective against breast cancer in Nigerian women. Huo D, Adebamowo CA, Ogundiran TO, Akang EE, Campbell O, Adenipekun A, Cummings S, Fackenthal J, Ademuyiwa F, Ahsan H, Olopade OI. Br J Cancer. 2008 Mar 11;98(5):992-6.

Prevalence of BRCA1 mutations in triple negative breast cancer. M. J. Kandel, Z. Stadler, S. Masciari, L. Collins, S. Schnitt, L. Harris, A. Miron, A. Richardson and J. E. Garber. Journal of Clinical Oncology, 2006 ASCO Annual Meeting Proceedings (Post-Meeting Edition). Vol 24, No 18S (June 20 Supplement), 2006: 508.

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