Breast cancer is the most common cancer diagnosed in women. According to 2021 research, it accounts for 1 in 10 new cancer diagnoses each year. Early detection of breast cancer is key to having the best treatment outcome, and knowing your risk factors makes detection that much easier.

Research tells us that there may be a link between having moles on your skin and developing breast cancer.

Common moles, also known as nevi, can be present on your skin from the time you are born. They can also appear on your skin because of sun exposure, as a natural part of aging, or even for no reason at all. Having moles doesn’t mean that you are going to develop breast cancer, even if you have quite a few.

Let’s take a look at what we know so far about the link between moles and breast cancer.

A 2014 study suggests that women with more moles might be at a higher risk of developing premenopausal breast cancer. Researchers analyzed records of 89,902 women in France. Out of that number, 5,956 developed breast cancer.

The study found that the women with “very many” nevi were more likely to have a family history of breast cancer. They were also more likely to develop the condition.

In another 2014 study with similar findings, researchers analyzed 24 years of health data from 74,523 female nurses. During those years, 5,483 of them developed invasive breast cancer.

The nurses with no moles were less likely to be diagnosed with breast cancer than the ones who had some nevi. Nurses in the study who had 15 or more nevi were 3 percent more likely to develop breast cancer.

Researchers from both studies theorized that hormones may play a role in how many moles you develop over your lifetime. Your levels of the hormone estrogen may be linked to both developing breast cancer and to having a higher number of moles. As of now, more studies are needed to understand the way estrogen does (or doesn’t) work to connect these two things.

Can a mole on your breast or nipple turn into cancer?

Moles anywhere on your body can become malignant. That includes moles on your breasts and nipples.

Cancerous moles are a symptom of melanoma, the most common type of skin cancer. In most cases, melanomas can be removed safely, noninvasively, and before the cancer cells have spread.

Having a melanoma on your breast is not the same as having breast cancer, which typically involves a lump or tumor. Follow-up for melanoma removal rarely involves chemotherapy, radiation, or biologic drugs that are usually part of a breast cancer treatment plan.

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Common moles are small growths on your skin. They’re typically darker than your natural skin color. Nevi form when pigment cells in your skin grow in clusters.

Most adults have between 10 and 40 moles. They tend to show up in areas that are exposed to the sun, like your face, hands, shoulders, and neck. When you have 50 or more moles, you may be at a higher risk of melanomas (skin cancer) as well as other types of cancer.

Everyone’s skin may look a little bit different with moles, but here are images of both benign and cancerous moles.

What do cancerous moles look like?

Cancerous moles look a little different from common moles. The National Cancer Institute (NCI) recommends using the ABCDE rule to identify moles that need attention from a doctor.

  • Asymmetry (A). A cancerous mole’s shape may be different on one half than on the other half.
  • Border (B). A cancerous mole may have a ragged or uneven border instead of presenting as round.
  • Color (C). A cancerous mole can be unevenly colored instead of one pigment throughout, with pink, black, white, or gray present.
  • Diameter (D). A cancerous mole may grow in size, taking on a thicker appearance.
  • Evolving (E). A cancerous mole may look different from how it looked a few weeks or months ago.
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Having a large number of moles is not currently an indicator that you need to be screened more often for breast cancer. However, it could be a good idea to get checked more often for melanomas.

According to the NCI, having 50 or more common moles is an indicator that you are at a higher risk of skin cancer. If you have a large number of moles but don’t have any other risk factors, you are still considered at average risk of developing breast cancer.

According to current breast cancer screening guidelines from the American Cancer Society:

  • Women ages 40 to 44 have the option to start getting mammograms every year and can perform a self-check every month.
  • Women ages 45 to 54 should get mammograms every year if they’re at average risk.
  • Women who are 55 years and older can switch to a mammogram every other year if they are still considered low risk at that point.

There are other risk factors for breast cancer that experts know more about. These risk factors can provide more concrete information as you consider your personal risk. According to the Centers for Disease Control and Prevention (CDC), they include:

  • Family history. If you have an immediate family member like a mother, sister, or daughter who has had breast or ovarian cancer, your odds of developing the condition are increased.
  • Genetic mutations. Inherited changes to certain genes have been identified as strong predictors of whether you will develop breast cancer.
  • Lifestyle choices. High amounts of alcohol consumption and low levels of physical activity have been linked to a stronger likelihood of breast cancer.
  • Reproductive history. If you do not become pregnant before the age of 30, do not experience a full-term pregnancy, and do not breastfeed, these are factors that may increase your personal breast cancer risk.
  • Medications. Radiation therapy, hormone replacement therapy, and the drug diethylstilbestrol have been connected to higher rates of breast cancer.

The number of moles you have may give some indication about your level of breast cancer risk. More research will hopefully shed light on exactly how strong this link is.

For now, counting your moles won’t necessarily give you a clear picture of your breast cancer risk. And evaluating your moles isn’t a better way of risk assessment than other proven methods we already have, such as analyzing your family history and checking for certain genetic markers.

If you are concerned about your breast cancer risk, talk with a doctor. They can determine your level of risk and provide individualized screening recommendations.