Does Lactation Not Protect Women of Mexican Descent? More Research Needed

Scientific data suggest that a woman reduces her risk of breast cancer by breastfeeding, having multiple children and giving birth at a younger age. A study led by the University of California, San Diego School of Medicine and recently published online by Cancer Epidemiology, Biomarkers & Prevention, indicates that women of Mexican descent may not fit that profile. In fact, results suggest that women of Mexican descent with more children and those who breastfeed are more likely to be diagnosed with triple-negative breast cancer.

The average age when women in the study gave birth to a first child was 23 years old. These women had an average of two to three children and were likely to breastfeed for long periods of time. Based on existing research, primarily based on non-Hispanic white women, this reproductive pattern would be classified as low risk. Yet all of the women in the study developed breast cancer, says Martínez.

The study enrolled breast cancer patients, 18 years old and older, at the University of Arizona Cancer Center, the University of Texas M.D. Anderson Cancer Center and three sites in Mexico – the Universidad de Sonora, the Instituto Tecnológico de Sonora and the Universidad de Guadalajara.

The study showed that patients of Mexican descent who breastfed for 12 months or more were more than twice as likely to have triple negative breast cancer. They were younger at diagnosis and younger during their first full-term pregnancy. Patients who had three or more children were also more likely to have triple negative breast cancer. Martinez said that it is important to note that prior studies, mainly in non-Hispanic white women, have shown that these reproductive characteristics reduce the risk of breast cancer overall, possibly due to effects on the more common, better prognosis, of luminal A cancers.

The most important takeaway from this report is that the scientific community needs to do further research into populations with unique risk-factor patterns that might benefit from different screening or prevention approaches. The observations made in this study need to be replicated in populations with similar reproductive profiles to determine if the results are due to common biologic factors or specific genetic or environmental factors.

[Taken from a news release from the University of California Health System.  Edited to eliminate unnecessary references to TNBC as automatically aggressive.]

• Read more about TNBC in my book, Surviving Triple-Negative Breast Cancer.

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