Naomi Johnston, age 15, of Akron, Ohio, for her question:
ARE SKIN CANCERS COMMON?
Skin cancers are the most common malignant tumors. A recent study estimates that there are more than 300,000 new cases of skin cancer each year, nearly three times as many as the most prevalent cancers of other organs.
But the good news in contrast to other cancers is that skin cancers are readily seen and detected and thus can be treated promptly.
The two most common types of skin cancer are called basal cell carcinoma and squamous cell carcinoma. They account for 29 out of 30 cases of all skin cancer. They are usually discovered when still localized and can be treated rather easily. They rarely lead to death.
Habitual or chronic exposure to the sun increases the risk of developing the basal cell and squamous cell forms of cancer. Persons most susceptible are those who sunburn easily and tan poorly, such as those of Irish, Scottish or Welsh background, and persons who work outdoors and receive prolonged sun exposure over many years, such as sailors or farmers.
Persons who have dark skin or who keep well covered have a lower incidence of skin cancer than those of fair complexion who take no precautions in the sun.
Basal cell carcinoma accounts for more than 75 percent of all skin cancers. The tumor arises when the basal cells of the epidermis proliferate abnormally and invade the dermis.
The most common type of basal cell cancer appears as a small nodule on the skin and eventually ulcerates in the center, intermittently bleeding and forming a crust. Bleeding and failure of the ulcer to heal should prompt the person to see a doctor.
The squamous cell carcinoma shows itself as a small growth with an irregular surface that bleeds. It is most often found on skin that has been chronically damaged by the sun.
Early diagnosis and treatment of the more serious malignant melanoma can bring good results, too. This cancer usually starts as a brown spot that enlarges on the skin. * * *
Melanomas can occur in people of any age, but the most common type hits those in their late 40s or 509. It usually begins as a brown spot on the skin and first appears during adulthood. The lesion gradually enlarges and assumes characteristic features: an irregular border, variation in color and an irregular surface.
Melanomas can occur anywhere, but the most common location is the back.
Frequently the easiest characteristic for a patient to notice is the irregular border, which is clearly different from the smooth, regular borders of benign moles.
Moles acquired after birth have a low chance of becoming malignant. In contrast, large moles present at birth, sometimes referred to as bathing trunk or garment congenital nervi, have about a one in 10 chance of developing melanoma.
A definite diagnosis of melanoma is made by examining a biopsy specimen under'the microscope. Once melanoma is diagnosed, the type of treatment is determined by how deeply it has invaded the underlying tissue.