When you visit SunDoctors for your annual skin check, the doctors will more than likely ask you if you have a family history of skin cancer. This is because melanoma can run in the family, with roughly 10% of melanoma patients reporting a family history of the disease.
Let’s take a closer look at the role of genetics in skin cancer development and discuss what steps to take if you or someone in your immediate family is diagnosed with skin cancer.
What is Skin Cancer?
Most skin cancer develops from exposure to UV radiation. This is the case in about 95% of all instances.
As our skin cells are exposed to ultraviolet light, the radiation damages their DNA, causing abnormal growths like tumours. Physical characteristics like your skin and hair colour (blonde or red hair), how many freckles or moles you have, your age and your history of sunburn impact your risk of developing skin cancer in life. Generally speaking, the older you are and the fairer you are, the more vigilant towards sun protection you should be.
Basal cell carcinoma (BCC) is the most common type of skin cancer in Australia. Despite rarely spreading to other organs in the body, it can destroy the surrounding tissue. Basal cell carcinoma appears as an open sore, a reddish patch, a growth with an elevated border and a central indentation, a bump or nodule or a scar-like area.
The other non-melanoma skin cancer is squamous cell carcinoma (SCC). It occurs in areas most exposed to the sun and develops when ultraviolet radiation mutates the outer epidermal layer of the skin and mucous membranes. Signs of squamous cell carcinoma include scaly red patches, elevated growths with a central depression, wart-like growths, nodules and open sores that may become scaly or bleed.
What is melanoma?
The most dangerous but least common skin cancer for Australians is melanoma. This type of skin cancer is highly invasive and can spread to other parts of your body if not detected early. Melanoma develops when melanocytes (pigment-producing cells) begin to grow abnormally, forming tumours and, thus, mirroring the appearance of a mole.
It's estimated that an Australian dies of melanoma every 6 hours.
The Genetic Component
People with a family history of melanoma or particular gene mutations have a higher melanoma susceptibility than the general population. This includes first-degree relatives: parents, brothers, sisters or children.
Doctors often recommend that close family members are also screened for melanoma when someone is diagnosed with it. This way, families suspected of carrying defective genes can be identified to aid prevention and treatment.
People with a combination of many unusual moles and a family history of melanoma are at an even higher risk of developing skin cancer. This is often called Familial Atypical Multiple Mole Melanoma Syndrome (FAMMM). Families with this genetic variant have moles that are called dysplastic nevi; that is, large, flat, irregular, asymmetric, and variably pigmented moles.
Key Genetic Markers
Several genetic markers and hereditary syndromes are known to increase skin cancer risk:
- Basal cell carcinoma: Basal cell nevus syndrome (BCNS) caused by pathogenic variants in PTCH1 and PTCH2.
- Squamous cell carcinoma: Oculocutaneous albinism, epidermolysis bullosa, and Fanconi anaemia syndromes.
- Melanoma: The major germline tumour suppressor gene, CDKN2A (cyclin-dependent kinase inhibitor 2A), is a risk factor for melanoma, and various pathogenic variants in it may account for 35% to 40% of all familial melanomas. CDKN2A oddly affects two proteins that control how cells divide. Germline pathogenic variants in several other genes, like CDK4, MITF, and BAP1 (BRCA1-associated protein-1) are also associated with an increased likelihood of melanoma risk.
An autosomal recessive disease called xeroderma pigmentosum (XP) is associated with an increased risk for all common skin cancer types, as it is a mutation in a gene required to repair ultraviolet radiation-induced DNA damage. Likewise, MC1R (melanocortin 1 receptor) is another tumour suppressor gene that increases melanoma risk. MC1R is important for regulating pigment in the body and is associated with freckling and red hair.
These mutations prevent the cell growth control that genes usually regulate. This causes cells that are damaged from UV exposure to only have a limited ability to repair themselves before developing into cancer.
Moreover, recent articles reveal that a hereditary breast cancer gene called BRCA2 may have associations with a slightly increased risk of melanoma.
Genetic testing is commercially available but is unlikely to alter recommendations received as part of skin cancer screenings. Since sporadic melanoma is much more common in Australia, testing won't be recommended unless three or more close relatives have developed invasive melanoma.
An option for families who know a parent carries a specific gene mutation that increases the risk of hereditary cancer syndrome is preimplantation genetic diagnosis (PGD). This medical procedure takes place in conjunction with in-vitro fertilisation (IVF) and, thus, is a complex procedure with financial, physical, and emotional factors to consider. However, PGD has been used for over two decades to mitigate the likelihood of cancer risk in children.
The procedure involves the removal of eggs and their fertilisation in a laboratory. Once the embryos have reached a certain level of development, a cell is removed for testing. If the hereditary condition in question is discovered in the embryo's cell, the parents can decide whether to transfer embryos that do not have the mutation. It is highly recommended that people seek more information at an IVF clinic.
Personalised Approaches to Prevention
Individuals with a close family member who has had melanoma should frequently and closely monitor their skin for changes. Thorough skin checks should be performed every 3 to 6 months. Be sure to follow sun safety advice — use SPF30+ sunscreen and wear protective clothing (hats, sunscreen, and high-coverage clothes).
At your skin screenings, it's helpful to ask questions tailored to your family and personal situation. Your doctors will be able to give you the most specific answers for your body, particularly if you are concerned about familial melanoma:
- Does it suggest the need for a cancer risk assessment for me and my family?
- Will you refer me and my family to a genetic counsellor?
- Should my family or I consider genetic testing?
- What preventive measures do you recommend for me and my family to reduce the risk of skin cancer?
Be on the Lookout
Ultimately, the best we can all do is watch for changes to our skin. Be aware of the number of spots you have, and any alterations in pigmentation and size, and minimise sunburns. If you have children, start early with skin checks, particularly in melanoma-prone families. Melanoma is the most common cancer in young Australians.
Fortunately, familial melanoma has a higher survival rate than non-familial melanoma due to the practice of careful observation and early detection. So, if you have FAMMM or other genetic risk factors, be sure to self-check your skin (even those hard-to-see places) more regularly and book professional skin exams several times a year.
At SunDoctors, we offer comprehensive skin care prevention, diagnosis, treatment, and management. Our clinics are equipped with resources and precise equipment for a streamlined skin cancer diagnosis, and our skin checks only take 15 minutes.
Any further questions about how your family might be at risk of skin cancer? Book a skin check appointment Online or speak to our friendly team, who are more than happy to provide any advice you may need.