Breast cancer: Having moles on your skin can increase risk of cancer, studies show

Breast cancer is the most common type of cancer diagnosed in women with a 2021 research showing 1 in 10 new cancer diagnoses is breast cancer. Experts advise regular checkup for women for early detection and best treatment outcomes. It is also prudent to be aware of what the risk factors are, including having moles, which has been linked to higher susceptibility to the tumour.

Having moles and risk of cancer

Moles also known as nevi in the medical community, are small growths on the skin that are dark, pink or tan with a distinct edge which develop when pigment cells grow in clusters.

It is estimated that most adults have between 10 and 40 of them on parts of the body that are mostly exposed to the sun. According to breastcancer.org:

While common moles aren’t cancerous, people who have more than 50 common moles have a higher risk of developing skin cancer.

A 2014 study found that women with ‘very many’ moles, stand a 13% risk of breast cancer than those without any or fewer moles. The conclusion was reached based on data from the analysis of 89,902 women in France - analysed over the course of many years - out of which 5,959 developed breast cancer.

The researchers also established that women who spot more moles, are also likely to have a family member with a history of breast cancer.

Role of estrogen

Another study conducted the same year, had similar findings after researchers studied 24 years of health data from 74,523 female nurses. During the course of the research, 5,483 of the nurses developed invasive breast cancer. According to healthline.com:

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.

However, both research teams concluded that more work needs to be done in this area to understand the role of estrogen in the link between having moles and risk of breast cancer.

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