There are three common genetic mistakes that can raise the risk of skin cancer. Most people know that exposure to excessive ultra-violet rays is the main pre-disposing cause of skin cancer later in life, but very few people understand why. The exposure usually occurs many years before there are any signs of skin cancer.
All cancers are diseases of DNA. Every gene has a DNA code that scientists represent by a sequence of letters. A “Genetic Mistake”, or mutation occurs when that sequence is altered for some reason.
There are two chief ways that Genetic Mistakes are brought about:
The DNA can be damaged by toxins (such as radiation, viruses or chemicals)
A Genetic Mistake can occur at the time of cell division. In normal cell division the genome in each cell duplicates itself before dividing. The copy is not always perfect, but most go un-noticed unless a key gene is changed. These cells with altered “key genes” come under different regulatory controls than normal body cells. They behave abnormally, dividing when they should not, moving out of their usual position in the body or even floating off in the blood stream and getting deposited in another organ before continuing dividing. That is how cancer comes about. It is thought to take up to 25 years from the time of the Genetic Mistake for a tumor to appear in an adult. This explains why skin cancer usually occurs later in life.
Scientists are now looking at the context of Genetic Mistakes. This helps them to identify what caused the mutation and to learn how the cancers developed. In the entire skin cancer range, all the signs point to UV rays as the cause.
There are three main types of skin cancer, basal cell carcinoma (BCC), squamus cell carcinoma (SCC) and Melanomas. Each one of these is caused by a genetic mistake occurring in a particular cell type:
- In BCC, the outer root sheath of a hair follicle is thought to be where the original genetic mistake occurs, because BCC occurs on hair-bearing skin. BCCs invade tissue locally and regionally, and have a tendency to form necrotic ulcers known as “rodent ulcers”. The gene most commonly found to be mutated in BCC’s is the “patched” (PTCH) gene that keeps cell growth in check. Changes in the gene allows cells to grow out of control.
- In SCC, the genetic mistake occurs in a more differentiated keratinocyte. It begins in smooth, hairless skin or on the border of the lip or scars. The gene most found to be altered is called the “p53”. That is the gene that normally causes damaged cells to die. When it is altered, the abnormal cells live longer and eventually become cancerous.
- In Melanomas, the genetic mistake occurs in the melanocytes along the skin base. The gene involved in controlling cell growth was changed in most melanomas. Code letters in the B-RAF gene were found to be altered in 70% of melanoma cases.
Genetic heritage may influence your risk of getting skin cancer, but skin cancers are caused by genetic mistakes, most commonly brought on by excessive exposure to UV rays in the past. In each of the three main type of skin cancer, a different cell type is mutated giving rise to that specific type of cancer. These three genetic mistakes raise the risk of suffering from skin cancer.
