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How many moles do you have on your skin? New study reveals some correlation between the number of moles & the incidence of breast cancer.

Breast cancer is one of the leading causes of death among American women right now. Researchers are constantly conducting studies relating to the disease to look for factors that show what might cause a woman to have an increased risk in getting breast cancer. Experts hope that such discoveries can help women who are at a higher risk by making them aware that they are at an increased risk and then encouraging them to take preventative measures. What could these measures include? There are many things women can do such as regularly check for lumps, get screened earlier, get extra testing to see if they are a BRCA gene carrier etc. The health and science community is buzzing this weekend about two particular new studies linking the number of moles women have to a higher propensity of acquiring breast cancer.

Reuters reports that the number of moles a woman has may be tied to her risk of developing breast cancer. Reuters explains what the studies are trying to show, “The studies do not prove that moles cause breast cancer or that women with a lot of moles will definitely get breast cancer. Instead, they suggest there may be a small genetic or hormonal link between the two.”

Many researchers expect that moles will possibly be used to help predict a woman’s risk of acquiring breast cancer based on the findings of these studies.

A team from Brigham and Women’s Hospital in Boston conducted one of the studies. “They used data collected on 74,523 female nurses between 1986 and 2010 to measure women’s breast cancer risk by the number of moles on their arms. Women with no moles had about an 8.5 percent chance of developing breast cancer during the study, compared to an 11.4 percent chance of breast cancer among women with 15 or more moles on their left arm,” according to Reuters. Women were told to count the number of moles on their left arm instead of their right because it is found that they use that arm more when driving, giving that arm more sun exposure (and sun exposure often causes moles, especially on fair skin).

The second study published similar findings. Reuters reports that these experts found, “That French women who reported having ‘very many moles’ were 13 percent more likely to develop breast cancer between 1990 and 2008 than women who had no moles. That study included 89,902 total women.”

The studies were published in PLOS Medicine this week. Many experts are taking the studies seriously and trying to delve further into whether this new connection should be used as a measuring tool in deciphering whether a woman will get breast cancer. They say this information is particularly relevant for when women reach middle age.

Dr. Gansler of the American Cancer Society commented on the study when speaking to CNN, “Women with a lot of moles are a little more likely to be diagnosed with breast cancer than were women with very few moles.”

He stated that there does seem to be a causal connection. What could be causing this link? Many say it is probably caused by estrogen, which influences hormones. Breast cancer and moles are both influenced by hormonal levels and researchers are saying it is not that the moles are causing breast cancer. It is that this connection shows that estrogen and hormonal levels which both reflect the number of moles on a woman’s body are affecting a woman’s propensity to get breast cancer later in life.

Estrogen is generally believed to drive breast cancer growth and researchers give special importance to any similar links that further this theory. Another expert explained to CNN how this new connection could be used for prevention, “Moles may be an indicator of a particular genetic make-up that predisposes women to be susceptible to cancer. If we can identify important causes, we can target them with interventions to reduce risk.”

CBS reports on the statistics offered by the studies.

“In two separate studies, American and French scientists found that the more moles a woman had, the greater her average risk of breast cancer. In one study, women with 15 or more moles on a single arm were 35 percent more likely to develop breast cancer than women with no moles,” according to CBS. While thirty-five percent sounds high it does not mean that if you have a lot of moles you will definitely get breast cancer, but rather it just says that there is most likely a connection between moles and the likelihood of getting breast cancer.

CBS news furthered the same idea that Reuters touched on...estrogen plays a more critical role in the development of breast cancer than any other hormone. Experts say estrogen feeds the growth of many types of breast tumors. And researchers have found that it influences mole growth as well. An example of this is the way moles get larger and darker during pregnancy. Experts told CBS that moles could be a lifetime marker of an exposure to estrogen, which explains why a high quantity of moles might mean a higher risk of getting breast cancer.

There is no concrete proof yet that women with a larger quantity of moles should start getting screened for breast cancer sooner. CBS gives a broad explanation of the statistics behind the study from Indiana University’s Simon Cancer Center, which looked at over 74,000 female nurses in the U.S.

“Back in 1986 -- when the women were 40 to 65 years old -- they were asked to count the number of moles on their left arm. Over the next 24 years, almost 5,500 women were diagnosed with breast cancer. And the odds, inched up with the number of moles the women had. Among women with none, 8.5 percent developed breast cancer; that rate was 11.4 percent among women with 15 or more moles. Women with 1 to 14 moles fell in between, with almost 10 percent developing breast cancer. Han's team considered a range of other factors -- including women's ages, lifestyle habits, weight, skin tone and sun exposure. Even then, women with the most moles were 35 percent more likely to develop breast cancer than those with none.”

Do not start frantically counting the number of moles on your body. Researchers are emphasizing the fact that there are still many other factors that are important in assessing whether a woman has a predisposition to getting breast cancer. One of these methods is genetic information. Genetic facts such as having the BRCA gene are still considered the primary way of assessing whether a woman has a higher risk of acquiring breast cancer.

Time magazine is voicing some particularly skeptical views about the new studies.

Time says, “The author of the second study, Dr. Kvaskoff of Brigham & Women’s Hospital and Harvard Medical School, says it’s possible it’s a hormonal issue, since it is known that moles get darker during pregnancy and skin pigment is responsive to hormones. But there could also be a genetic component, since when Kvaskoff and her colleagues adjusted for history of breast disease, they found the association decreased.”

Time emphasizes the fact that other experts in the field such as Dr. Schnabel of NYU Perlmutter Cancer Center say that the studies will not change medical standards of dealing with breast cancer at all. Dr. Schnabel told Time, “The modest connection does not tell us much at all. From the perspective of why there’s an association, there is really not much to say. This is one of those situations where you have statistical connection, but there is no sense of underlying mechanism. There is no clear causality and nothing to explain why.” She further stated that genetic history is the most effective tool in predicting whether a woman is highly susceptible to developing breast cancer.

While some are uncertain about how helpful the studies’ findings are, many experts in the field are stating that the newly found link is a breakthrough. Researchers plan to go forward with more studies to see whether high mole numbers truly can be used to assume that a woman has a higher predisposition to getting breast cancer. In today’s world where breast cancer is killing countless American women every year experts are eager to discover any causal factors so that they can help women at risk take preventative steps.  


Gerry Oginski
NY Medical Malpractice & Personal Injury Trial Lawyer