The link between moles and the development of melanoma is not as direct as many people assume. In fact, moles themselves are not an indicator of the risk of melanoma and skin cancers, but rather the actual physical appearance of the mole is the key. According to the Melanoma Education Foundation the risk of a normal mole developing melanoma is approximately one in 3,000 while the same risk goes up to 1 in 100 if the mole is atypical. To further demonstrate this issue they also report that only about 30% of melanomas of the skin develop from pre-existing moles with approximately 65% developing on unblemished areas of the skin.1
Although moles are a significant concern and should be routinely monitored with self skin exams as well as check ups with your doctor most people with moles will never develop any form of melanoma. Taking precautions such as protecting your skin from exposure to the ultraviolet rays of the skin is one of the most proactive protections that can be put in place. This is particularly important if you have light skin, light colored hair, red hair and freckles or have a history of burning.2
The following are considered the risk factors for people with moles in the development of melanoma, the most significant form of skin cancer.
Number of Moles
Research shows that individuals with multiple moles, typically more than 50 over their body, are at greater risk for developing melanoma than people with fewer than 50 moles. This is because with increased moles is the increased likelihood of abnormal melanocytes, which is an indicator of cancer. The greater the number of moles that you have on your body the greater the chance that some will be atypical, which is the biggest risk factor for cancer.3
Atypical Moles
Atypical moles are irregular in shape and borders, have variations in color within the mole and are larger than approximately 5 millimeters in diameter. The size component is not always accurate as a predictor; some smaller moles can also be cancerous if there are other variations present. Atypical moles, also known as dysplastic nevi, are common on areas of the body that have been exposed to the sun, sunburns or other types of light sources such as tanning beds.
Atypical moles can also be found in families. This is known as atypical mole syndrome or familial atypical multiple mole-melanoma (FAMMM). Having this condition, which is characterized as groupings of moles combined with a history of melanoma in the family, can also predispose individuals to a higher incidence of systemic cancers.4
Atypical moles need to be carefully monitored using the ABCD system that checks for changes in asymmetry, borders, color and diameter of the mole. In addition new moles that develop after the age of 20 or in areas of the body not typically associated with exposure to the skin should be checked by a dermatologist as quickly as possible. Moles that start with a bump or lump under the skin are also high risk moles and may actually be a condition known as nodular melanoma. This is a highly aggressive and potentially rapidly spreading melanoma that, if diagnosed early, can be very successfully treated.
Geographical Location
The closer people live to the equator, which allows more direct UV exposure, and those that live at higher elevations are more likely to develop melanomas. This is particularly true if light skin is combined with these geographic locations. Even people with dark skin that live in areas of high altitudes and high sunlight are more likely to develop atypical moles and melanomas than those with the same skin coloration and ethnic backgrounds living in lower or more moderate climates. Research in Australia shows that melanoma is also linked to where you live. People living in the city reported lower rates of skin cancers compared to people in the same geographic area that live in rural areas.5
Researchers believe that men in rural areas are also more likely to experience sunburns and longer exposure to the sun without any protection for the skin. This may be factored into the increasing rate of melanomas in men worldwide.
Family History
Individuals with a family history of melanoma or skin cancers should very carefully monitor any moles that they have on their body. This is because there is a genetic component to melanoma that may or may not be accompanied by large numbers of moles and freckles on the body. Even family members with very few moles that have an immediate relative such as a father, mother, sister, brother or a child that has been diagnosed with melanoma are at greater risk for developing melanoma themselves.
People with a family or personal history of skin cancer and that have moles or dysplastic nevi should have regular skin examinations by a dermatologist, not just a family doctor. The dermatologist can be much more effective in determining early and slight changes in the structures of the moles because of his or her specialized training. This early detection is essential in effective treatment since approximately 5 to 10% of all people with melanoma will have a reoccurrence.6
There are other risk factors that, when atypical moles are present, increase the risk of developing melanoma. This can include patients that are being treated for autoimmune disorders and those that have recently undergone transplants.
References
1 About Melanoma: How Does It Start. (n.d.). Retrieved from Melanoma Education Foundation: www.skincheck.org/Page2.htm#moles
2 Melanoma. (n.d.). Retrieved from National Cancer Institute: www.cancer.gov/
cancertopics/wyntk/moles-and-dysplastic-nevi/page4
3 Melanoma Risk Factors. (n.d.). Retrieved from Mayo Clinic: www.mayoclinic.com/health/melanoma/DS00439/DSECTION=risk-factors
4 Bergman, W. (1990). Systemic cancer and the FAMMM syndrome. British Journal of Cancer 61 (6) , 932-936.
5 Duncan, M. J. (2008). Geographical locale and sunburn in Queensland adults. Australian Journal of Rural Healthy (16) , 181-182.
6 What are the risk factors for melanoma? (n.d.). Retrieved from American Cancer Society: www.cancer.org/Cancer/SkinCancer-Melanoma/DetailedGuide/melanoma-skin-cancer-risk-factors
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