From a scientific standpoint, triple-negative breast cancers (usually invasive ductal carcinomas) are those whose cells lack estrogen and progesterone receptors, and do not have an excess of the HER2 protein on their surfaces. Because the growth of the cancer isn’t supported by these hormones or too many HER2 receptors, it doesn’t respond to common hormonal therapy (such as tamoxifen) or therapies that target HER2 receptors, such as Herceptin.
Anyone can get triple-negative breast cancer, but it is more likely to occur in premenopausal women, says Patricia Prijatel, author of “Surviving Triple-Negative Breast Cancer” (Oxford University Press, 2012) and founder of the Positives About Negative blog (HormoneNegative.BlogSpot.com). In addition, although African-American women are less likely to get breast cancer than Caucasian women, if they do get it, they are more likely to get triple-negative.
While this group of cancers is not hereditary, Prijatel notes that it does have a strong association with the BRCA genetic mutation, which is hereditary. “The correlation works one way, but not necessarily the other,” she adds. “Women with the genetic mutation who get breast cancer are most likely to have triple-negative breast cancer than other forms, but women with triple-negative breast cancer do not necessarily have the mutation.”
Other studies have found that women with triple-negative were younger at the onset of menstruation, on average had more children (at least three) than non-triple-negative women, they were less likely to breast-feed for more than four months, and they were more likely to not breast-feed at all if they had at least three children, Prijatel says. Another risk factor she finds intriguing is related to metabolic syndrome — a combination of risk factors such as high blood glucose, high blood pressure and abdominal obesity, plus problems like low “good” cholesterol, high “bad” cholesterol and high triglycerides. “Women diagnosed with triple-negative breast cancer are much more likely to have metabolic syndrome than those with other forms of breast cancer,” Prijatel says. “Some research suggests that insulin resistance might be associated with triple-negative breast cancer.”