Various factors may increase a woman's risk of developing breast cancer. But the size of a woman's breasts may not help doctors determine the gravity of that risk.
Researchers have uncovered connections between some genes that determine a woman's breast size and those involved with breast cancer, but those discoveries are not enough to determine a definitive link.
Scientists at commercial DNA testing service 23andMe in California have found a correlation between the genes that determine whether a woman will wear a B cup or a D cup bra and the genes associated with breast cancer risk. Data from more than 16,000 female customers who had their genetic makeup examined was analyzed, particularly single nucleotide polymorphisms, or SNPs. SNPs are variations in DNA that may or may not have impact on predisposition to certain traits or illnesses. The researchers identified seven SNPs as "significantly associated" with breast size, three of which had previously been linked to breast cancer risk.
Doctors say that it is unlikely breast size alone will dictate propensity for breast cancer. Others have argued the DNA study was preliminary and possibly flawed because it failed to account for complete information, such as breast density, participants' weight or alcohol consumption -- all factors that can contribute to breast cancer risk.
Excess body weight, which can contribute to larger breast size, may be a more likely culprit in the correlation between cup size and cancer. The American Cancer Society says that as many as 20 percent of all cancer-related deaths were impacted by excess body weight. Being overweight or obese is clearly linked with an increased risk of breast cancer, especially in women past menopause, but not necessarily in women of childbearing age. The reasons for this are unclear.
There is not a large enough body of evidence to link large breast size to an increased risk of breast cancer. It's true that larger breasts have more breast cells susceptible to mutation, but many surmise that genetics and lifestyle factors are more likely than breast size to elevate a woman's breast cancer risk.
Women concerned with breast cancer risk should complete a family history and speak with their doctors to address their concerns. Frequent self-examinations as well as routine physicals can make women more familiar with their breasts and more likely to recognize if anything is amiss.
What about implants?
According to a study published in the Journal of the American Medical Association, although breast implants may decrease accuracy of mammograms, they do not raise a person's risk of developing breast cancer. Women who have larger breasts due to implants do not necessarily have a greater risk of developing breast cancer. Likewise, women who have had implants used in breast reconstruction procedures do not need to worry about their cancer coming back due to the implants. In fact, newly developed implants may deter the growth of cancerous cells in breast reconstruction patients. Researchers at Brown University developed a new kind of implant that has a microscopically bumpy surface, which can impede the growth of blood vessels that typically feed cancerous tumors.