Skin cancer was once considered a disease that affected mainly adults as a result of years of exposure to ultraviolet (UV) rays. In recent years, however, doctors began seeing skin cancer in children as well. Since children have not had the years of sun exposure believed to be needed for cancer development, scientists began to look for another reason. Research found that a defective gene may be to blame.
When the enzymes responsible for repairing DNA damage, called nucleotide excision repair enzymes, are mutated, it can lead to mutations in other cells, altering the genes in them. If one of these genes is a type that suppresses cancer, it may actually reverse its actions and begin inducing tumors.
Nucleotide excision repair enzymes are also responsible for repairing UV damage. The mutated enzyme is unable to repair damage, leaving skin vulnerable to additional damage each time it is exposed to UV radiation. In severe cases, sunlight must be avoided completely.
The disorder of mutated nucleotide repair enzymes is called xeroderma pigmentosum, or XP for short. This condition is an autosomal recessive genetic disorder. There must be two copies of the mutated gene. If both parents are carriers, individuals who have a defective gene but are otherwise unaffected, there is a 25% chance that their child will not carry the gene, a 25% chance their child will have xeroderma pigmentosum and a 50% chance that their child will become a carrier.
This disorder often leads to the development of skin cancer in children. Any of the three types of skin cancer may develop. However, metastatic malignant melanoma and squamous cell carcinoma are typically the cause of death for patients with this disorder. The prognosis for affected individuals is grim. Over 60% do not live past th age of twenty, although mild cases have lived to middle age.
While the condition is rare in the United States, approximately one case per million people, in other countries it is more prevalent. Japan has an estimated one case per forty thousand people. North African and Middle Eastern populations also appear to have a higher incidence of skin cancer in children.
The first symptom is usually the appearance of a severe sunburn after a very short exposure to sunlight. The sunburn may last for weeks. Other signs may include early development of freckles, thin skin that is extremely dry, painfully sensitive eyes in sunlight or premature aging.
Treatment involves limiting exposure and, in some cases, taking medications or supplements. Parents of children with xeroderma pigmentosum should strictly limit the child’s sunlight exposure. If exposure is unavoidable, care should be taken to block as much of the UV rays as possible. The use of sunscreen, UV protective clothing, sunglasses, hats or other protective devices should be used.
Individuals who develop keratosis, keratin growths on the skin, may be prescribed Isotretinoin. However, there are significant side effects with the medication. Since limiting sunlight inhibits the body’s production of Vitamin D, a supplement may also be necessary.
There is no cure for this disorder that causes skin cancer in children. The damage is done before the child is even born. While protection from the destructive effects of UV radiation is important for all children, it is even more so for children with xeroderma pigmentosum.
by A Hurrell