Skin Cancer

Skin cancer is the most diagnosed cancer in this country. The most common type of skin cancer is keratinocyte cancers such as basal cell carcinomas and squamous cell carcinomas, which come from the main cell type of the epidermis and are most often caused by the effects of ultraviolet radiation on the skin. They are generally localized and rarely move to other areas. These cancers are easily identified as sores that won’t go away or crusting patches that grow mostly on sun-exposed parts of the body such as the hands, neck, arms, and face, they can be treated with routine surgical procedures. Malignant melanoma is a potentially serious type of skin cancer due to uncontrolled growth of pigment cells, called melanocytes. Melanomas are most common in white skinned people, but rarely develop in those with dark skin. There are many factors that can affect who deals with this, including inherited genes and genetic defects (gene mutations) that are acquired due to environment factors, such as excessive sun exposure. Gene mutations that are passed down from parent to child can increase the risk of melanoma.

Variation in skin, hair, and eye pigmentation between people of different ancestries is one of the most noticeable human characteristics; it is very well known and understood that human skin color, hair color, and eye color is mostly genetic. The MC1R gene provides instructions for making a protein called the melonocartin 1 receptor. This receptor plays an important role in normal pigmentation such as red hair, freckling, and sun sensitivity. This receptor is primarily located on the surface of our melanocytes, which are the specialized cells that produce the pigment called melanin. Differences in pigmentation between people are largely the result of differences in the amount and types of melanin produced, and packaging of melanin, and not the number of melanocytes. A number of influences are at work to explain this diversity of colors. First, repeated exposure to UV Rays causes an increase in melanin production and possibly an increase in melanocytes. Second, different body sites are preprogrammed to have different numbers of melanocytes and melanin production. Third, the amount and type of melanin production vary with age and by site made, with children being paler skinned than adults, and females paler than males.
“Many cancers begin when one or more genes in a cell are mutated (changed), creating an abnormal protein. A person may either be born with a genetic mutation in all of their cells (germline mutation) or acquire a genetic mutation in a single cell during his or her lifetime sometimes as a result of exposure to environmental factors, such as UV rays from the sun. Most melanomas (about 90%) are considered sporadic, meaning that the damage to the genes occurs by chance after a person is born, and there is no risk of passing on the gene to a person's children. An increased risk of melanoma occurs when specific gene mutations are passed within a family from generation to generation. Such inherited melanoma is sometimes called familial melanoma. An inherited risk of melanoma is suspected if two or more first-degree relatives (parents, brothers, sisters) are diagnosed with melanoma. The risk is higher if several family members that live in different locations have been diagnosed with melanoma.” (paragraph 3)

Citations

Nouri, K. (2008). Skin Cancer. New York: McGraw-Hill Medical.
Ghayourmanesh, S. P. (2014). Skin cancer. Magill’S Medical Guide (Online Edition),
Nouri, K. (2008). Skin Cancer. New York: McGraw-Hill Medical. Anoma Ranaweera B.V. Sc; PhD. (2015). Clinical Biochemistry, University of Liverpool, UK