Marmur Medical Blog

My family has a history of melanoma . . . what does this mean for me?

I come from a family where one side is plagued by heart attacks, and the other afflicted by cancer. At the moment, my chances of surviving over the age of 60 are looking pretty slim. Thankfully, I seem to have inherited the low blood pressure and cholesterol of my cancer-afflicted side of the family, so I have one of my odds beaten. Since starting medical school and becoming interested in dermatology, I have become painfully aware of just how many things can go wrong with your skin, including cancer. Though I wear SPF-containing lotion every day, I still wonder how worried I should be about developing the deadliest skin cancer of them all, melanoma.

Melanomas are malignant tumors composed of melanocytes, the cells in our body responsible skin coloration. Though melanoma is a less common skin cancer, it is nevertheless one of the most dangerous. According to the WHO, in 2006, melanomas were the cause of 48,000 deaths worldwide, accounting for over 70% of all skin cancer-related deaths. If caught early, the prognosis of melanoma is quite good with a five-year survival rate of around 90%; however, with time, melanomas have the capability of metastasizing to distant areas of skin, lymph nodes and even lungs, thus lowering the survival rate to below 20%. It sounds scary, but really all the statistics are saying is that if caught early, the chances of death due to a melanoma or a melanoma-related malignancy is relatively low.

Just like any other cancer, melanomas are caused by DNA damage, either environmental or inherited. Most likely, if one develops melanoma it will be due to a build-up of acquired (as opposed to inherited) mutations over a lifetime of sun-damage (UV A and UV B), chemical exposure (coal tar, pitch, creosote, arsenics, radium), and other “life” factors (let’s face it, living is a fatal undertaking). However, there are some people in the population who may be predisposed to develop a cancer such as melanoma due to their “genetic make-up”.

Statistics gathered by national cancer agencies have shown that one in ten patients with melanoma has a family member previously diagnosed with melanoma; those who had first-degree relatives (father, mother, siblings) diagnosed with melanoma were 50% more likely to develop a melanoma themselves. Most “inherited” melanoma, known as familial melanoma, is genetically heterogeneous meaning a person from a family known to have melanoma history has inherited one “bad” copy and one “good” copy of a gene locus thought to predispose the development of melanoma. Without getting into a genetics lesson, it’s obvious that being afflicted with one “bad” copy of a gene at birth, makes it is much easier to damage the one “good” gene left during the course of life. Just like ice-cream, gene mutations come in a variety of different flavors (i.e. severities) from high penetrance (the chance of carrying a mutation at birth is very high) to low penetrance (the chance of carrying a mutation at birth is low). In addition, some mutations may confer a higher or lower risk to developing of melanoma. For example, the MC1R gene encodes for dark hair and dark skin. A person with a mutated MC1R gene (light hair and light skin) is two to four times more likely to develop melanoma than a person who carries two wild-type (i.e. non-mutated) copies of the MC1R gene. Other genes that may be mutated in ways that promote the development of melanoma include BRAF, p53 and CDKN2A, all genes controlling cell proliferation and cell repair mechanisms. Mutations in these genes may cause abnormal growth and the inability to repair damage caused by environmental factors.

If you don’t feel the particular need to have your genome tested for predisposing genes at this point in your life, there are some things that you should be aware of. Even if the genes passed on to you by your mother and father are mutation free, there are many factors that will still increase the risk of developing melanoma including: UV A and UV B exposure (whether it be from direct sun or the tanning salon), a history of blistering sun burns, fair skin with light hair and eyes, a greater number of moles on your body (especially “funny” looking atypical moles known as dysplastic nevi, so remember the ABCDE rule), a compromised immune system (from chemotherapy, HIV/AIDS, organ transplant or lymphoma) and a personal history of a previous melanoma (just like with any cancer, once developed there is always an increased risk for the development of the same cancer again). Even though there is a familial “passing-on” of the melanoma torch, you can reduce your risk of developing melanoma by applying sunscreen, wearing a hat, performing skin checks (on yourself and at the dermatologist’s office to catch the progression of cancerous moles early) and avoiding contact with environmental carcinogens.

Being predisposed to developing melanoma doesn’t mean life as you know it is over, it just means you have be a little more careful with environmental assaults on your skin and a little more vigilant when it comes to checking your moles. If you’re not genetically predisposed to melanoma, it doesn’t hurt to take a few minutes each day to put on sunscreen or check your skin; protecting your skin more will keep you from becoming a WHO statistic. When you’re 90 and melanoma free or the survivor of a melanoma caught early, you’ll be happy that you beat the odds.

Note: Melanoma can also involve the colored part of the eye. Just like you skin, eyes have melanocytes to produce pigment! Though material on melanoma of the eye is not covered in this article, many optometrists and ophthalmologists look for melanomas during yearly check-ups. If you have a family history of melanoma, it may be prudent to warn your eye doctor so they can keep a close “eye” (pun fully intended) on you.

Written by:
Margit Lai Wun Juhasz
Mount Sinai Medical Student