Skin cancer is diagnosed in about one million people in the U.S. each year, according to the National Cancer Institute. The skin has two layers, the epidermis and the dermis. The epidermis is the topmost layer, and consists of squamous cells, basal cells and melanocytes, which produce the pigment responsible for skin color. Being in the sun without sunscreen exposes the skin to harmful ultraviolet rays, which increase a person's risk of developing this form of cancer. Skin cancer occurs when one of these cell types becomes cancerous.
Melanoma
Melanoma causes the melanocytes of the epidermis to become cancerous. The National Cancer Institute reports that melanoma is a rare type of skin cancer, accounting for only a little over 53,000 cases of skin cancer. However, melanoma proves the most deadly type of skin cancer and causes 75 percent of all deaths due to skin cancer, according to the Penn State Hershey Medical Center. Because the cancerous melanocytes commonly still produce colored pigment, melanoma cells often look dark brown or black in color. Melanomas can develop on the skin all over the body, but more commonly develop on the chest and back in men, the legs in women or the face and neck in both sexes.
Basal Cell Carcinoma
This form of skin cancer forms from the basal cells in the bottommost layer of the epidermis. This is the most common form of skin cancer, accounting for about 80 percent of skin cancer cases, according to the American Cancer Society. Basal cell carcinoma often recurs after treatment, on either the same place or elsewhere on body. This form of skin cancer typically proves slow growing and rarely spreads as long as the cancer receives treatment over the long-term.
Squamous Cell Carcinoma
Squamous cells are very thin flat cells in the upper layer of the epidermis, and squamous cell carcinoma occurs with these cells transform into cancer. However, not all squamous cell carcinomas are skin cancer, as the National Cancer Institute reports that squamous cells also line the respiratory and digestive tracts. This proves a less common type of skin cancer, making up about 20 percent of all skin cancer cases. Squamous cell carcinoma grows and spreads at a faster rate than basal cell carcinoma, and sometimes, though not often, spreads to the tissue underneath the skin or distant sites in the body.
References
- The National Cancer Institute: What You Need to Know About Skin Cancer
- Penn State Milton S. Hershey Medical Center: Skin Cancer
- American Cancer Society: What is Squamous and Basal Cell Skin Cancer
- American Cancer Society: What is Melanoma?
- The National Cancer Institute: What You Need to Know About Melanoma.
