Cancer of the skin effects upwards of one million Americans every year. One out of seven Americans will develop cancer of the skin in their lifetime. Ninety percent of all skin cancers are totally curable if taken care of early in their course. The three most common types of skin cancers are basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.
Basal cell carcinoma is the most common and least serious of the three major types of skin cancer. This type of skin cancer frequently presents as a benign appearing lesion, which looks much like a pimple or smooth bump with shiny or raised edges. As it progresses, there can be crusting and intermittent bleeding from its surface.
Squamous cell skin cancer is the next most common type of skin cancer. It is more serious because it is a more aggressive cancer locally, and can spread to lymph nodes, and therefore vital organs. A squamous cell cancer is generally preceded by a pre-malignant lesion known as an actinic or solar keratosis. This keratosis is usually a slightly raised, rough, red patch, which may flake, itch, or bleed.
The deadliest form of skin cancer is a malignant melanoma. This type of skin cancer is the least common, but most dangerous variety. It will be discussed in more depth later in this overview.
As a general rule, the seriousness of a skin cancer is directly proportional to the aggressiveness of the tumor, both from the standpoint of local growth, and its potential for metastasis. Cancer metastases are defined as malignant cells which spread in the blood stream or lymph nodes to establish malignant colonies in other parts of the body. Vital organs are thus eventually destroyed and death ensues.
Symptoms that should alert one to the possibility of skin cancer are:
- A skin sore that does not heal, heals intermittently, or re-opens.
- A dry, scaly, red patch.
- A raised, waxy, or shiny bump.
- A wart or mole that changes in size, color, surface characteristics, elevation, or sensation (especially itching).
High-risk individuals include those of Celtic origin, i.e.: Ancestry north of the 45th parallel with fair skin, light colored eyes, red or blond hair, and freckles. Certain medical illnesses also predispose individuals to skin cancers; the most common being xeroderma pigmentosa, dysplastic nevus syndrome, basal cell nevus syndrome, nevus sebaceous and others.
Ninety percent of skin cancers are sun related. Their incidence is directly related to frequent, regular sun exposure, which causes cumulative effects on the skin. With this direct causal relationship, the most significant controllable factor appears to be limitation to sun exposure, i.e. exposure to ultraviolet (UV) rays. Ultraviolet rays of the sun cause cell injury in the skin. They damage epidermal and dermal cells causing genetic changes. They also weaken the body’s general immunity to both skin cancers and other types of cancer. Ultraviolet rays also break down collagen and elastin in the deeper layers of the skin giving rise to premature aging (photo aging) and wrinkling of the skin.
Prevention of skin cancers by eliminating the common causative factors is obviously the ideal situation. However, early detection of skin cancer by regular exams certainly makes them more curable. Even though many skin cancers do not kill, they can, in advanced stages, produce significant disfigurement; for example, loss of a nose, an ear, or an eyelid to effect a cure. Significant scarring may result upon removal of large areas of cancerous growth on the head, face, and neck. Prevention through regular exams, and treatment of pre-malignant skin lesions early, especially actinic/solar keratosis, is strongly recommended.
Once established, skin cancers can be treated by a variety of common methods. Basal cell skin cancers are generally treated by electrodesiccation and curettage, cryotherapy, radiation therapy, or complete excision. Squamous cell cancers are treated by excision. Melanomas are treated by wide excision, lymph node dissection when indicated, and possibly chemotherapy and immunotherapy for more advanced cases.
Moh’s micrographic surgery has the highest cure rate for basal cell and squamous cell skin cancers. It is not generally recommended for malignant melanoma, however. This is a highly specialized form of skin cancer removal that is used mostly for recurrent tumors, and tumors in difficult locations that generally have high recurrence rates. It is also indicated in critical facial regions such as the nose, ears, and eyelids, where the minimal amount of tissue to effect a cure should be removed, but no more. This is a critical consideration in regions of the face where reconstruction options are limited and complicated.
Alternative and more experimental methods for prevention and treatment for various types of skin cancers include dietary supplementation with high dose beta-carotene or vitamin C and E. These may be used as a preventative therapy in individuals with a prior history of skin cancer. Low dose retinoids, which are derivatives of vitamin A, are at times used as a preventative therapy both in regard to the development of skin cancer, and premature aging of the skin caused by actinic damage. In the treatment of malignant melanoma, various stimulants to the immune system have been attempted in advanced cases.
MALIGNANT MELANOMA
Malignant melanoma is the most dangerous form of skin cancer. This is due to the aggressiveness of the tumor and the high risk of metastatic disease. There are 23,000 new cases of malignant melanoma per year in the United States. The overall mortality rate at 5 years is 40 percent. There is a virtual epidemic in the rise of malignant melanoma. In 1930, Caucasian Americans had a lifetime risk of 1:1500. Today that risk is 1:150. Colorado has one of the highest malignancy rates in the world. The incidence of malignant melanoma in Colorado is increasing rapidly.
Causative factors in malignant melanoma include not only the cumulative effects of the sun over a period of time, but also to a greater degree, intermittent, painful, blistering sunburns that occur in childhood or early adolescence. A recent Harvard Medical School study suggests that even a single serious blistering sunburn in adolescence or childhood can double the risk of skin cancer later on, regardless of the total cumulative sun exposure or skin type. It is theorized that a serious burn may alter the genetic material in the pigment cells of the skin of a growing child, leading to the formation of unstable moles, which have the potential to turn malignant. Other risk factors include a family history of malignant melanoma, dysplastic nevi, or large congenital nevi.
With dysplastic nevi, the risk of malignant melanoma is 10 percent. With both a family history of malignant melanoma and dysplastic nevi, the risk approaches 100 percent. There is some controversy in the medical literature regarding the incidence of malignant melanoma in large congenital nevi, but commonly the risk quoted is 5-20 percent. Again, the general risk of malignant melanoma for the population as a whole is approximately 1.5 percent, i.e.: 1:150 in Caucasian Americans.
Earlier detection results in higher cure rates. A recent study at New York University Medical Center suggests a 10 a year survival for malignant melanoma less than .76 mm. thick is 99 percent. In contrast, the 10 year survival for a malignant melanoma greater than 3 mm. in thickness drops to 48 percent. The implication here is that early diagnosis of melanoma is critical to achieving a cure.
Early signs of malignant melanoma are a change in a pre-existing mole, or development of a new mole. Change in an existing mole is considered a ‘medical emergency’ by many clinicians. Non-malignant moles can certainly grow and change and not be malignant. Many times these require only careful follow up and possible serial photographs to document their change or stability.
Early signs of malignant melanoma include changes in a pre-existing mole, or the appearance of a brown-black or multi-colored patch where previously one did not exist. These changes are described as the ABCD’s of melanoma. ‘A’ (asymmetry): A line down the center of many malignant moles would not leave two matching halves as in the case of common moles. ‘B’ (border): Many malignant melanomas have uneven ‘ragged’ edges as opposed to the smooth, even borders of non-malignant moles. ‘C’ (color): Often malignant melanomas have two or more colors ‘ usually black and brown, and sometimes blue and white. Non-malignant moles are generally one color. ‘D’ (diameter): Melanomas are usually larger than normal moles, which are 6 mm. or less in diameter (the size of a pencil eraser).