Disease: Skin Cancer
(Nonmelanoma Skin Cancer)

    What is skin cancer?

    Skin cancer is a common, usually low-grade cancerous (malignant) growth of the skin. It starts from cells that begin as normal skin cells and transform into those with the potential to reproduce in an out-of-control manner. Unlike other cancers, the vast majority of skin cancers have no potential to spread to other parts of the body (metastasize) and threaten your life.

    There are two major types of skin cancer, basal cell carcinoma (the most common) and squamous cell carcinoma (the second most common). Melanoma is also a form of skin cancer but is far less common, though more dangerous, than the other two varieties.

    What are the risk factors for skin cancer?

    The most common risk factors for skin cancer are as follows.

    • Ultraviolet light exposure, either from the sun or from tanning beds: Fair-skinned individuals with a history of repeated sunburns, those with hazel or blue eyes, and people with blond or red hair are particularly vulnerable. The problem is worse in areas of high altitude or near the equator where sunlight exposure is more intense.
    • A chronically suppressed immune system (immunosuppression) from underlying diseases such as HIV infection or cancer, or from some medications such as prednisone or chemotherapy
    • Exposure to ionizing radiation (X-rays) or chemicals known to predispose to cancer such as arsenic
    • Certain types of wart virus infections
    • People who have a history of one skin cancer have a 20% chance of developing a second skin cancer in the next two years.

    What causes skin cancer?

    The exact cause of skin cancer is not known. It appears that basal cell cancers arise from basaloid cells in the upper layer of the skin. Uncontrolled growth of these cells is regulated by other factors in the skin. When that regulation is lost, skin cancer cells begin to grow into tumors.

    In squamous cell cancers, the tumors arise from a normal cell in the top layer of the skin, the epidermis. As with basal cell cancers, these cells are prevented from growing wildly by genetically controlled factors. When there is an alteration in the genes that regulate these cells, the control is lost and skin cancers start to grow. In many instances, the genes are altered by sunlight exposure.

    What are the different types of skin cancer?

    There are several different types of skin cancers:

    • Basal cell carcinoma is the most common cancer in humans. Over 1 million new cases are diagnosed in the U.S. each year. There are several different types of basal cell carcinoma, including the superficial type, the least worrisome variety; the nodular type, the most common; and the morpheaform, the most challenging to treat because the tumors often grow into the surrounding tissue (infiltrate) without a well-defined border.
    • Squamous cell carcinoma accounts for about 20% of all skin cancers but is more common in immunosuppressed people. In most instances, its biologic behavior is much like basal cell carcinoma, with minimal chance of spread. However, some of these tumors can act in an aggressive fashion and can even metastasize and cause death.
    • Less common skin cancers include melanoma, Merkel cell carcinoma, atypical fibroxanthoma, cutaneous lymphoma, and dermatofibrosarcoma.

    What are the signs and symptoms of skin cancer?

    Most basal cell carcinomas have few if any symptoms. Squamous cell carcinomas may be painful. Both types of skin cancer may appear as a sore that will not heal. There is often a slowly growing bump on the skin that may bleed after minor trauma. Basal cell carcinomas may have a pearly color while squamous cell carcinomas may have a thick scale on the surface. Both may have raised edges and a central ulceration.

    When is a mole dangerous or high-risk for becoming a skin cancer?

    Moles are almost always harmless and only very rarely turn into skin cancer. If a mole becomes cancerous, it would be a melanoma. There is a precancerous stage, called a dysplastic nevus, that is somewhat more irregular than a normal mole. Moles never become squamous cell carcinomas or basal cell carcinomas.

    What are the most common sites where skin cancer develops?

    Skin cancers typically arise in areas of the skin exposed to the sun repeatedly over many years such as the face, ears, back of the neck, and the bald area of the scalp. Less commonly, these tumors may appear at sites with only limited sun exposure such as the back, chest, or the extremities. However, skin cancer may occur anywhere on the skin.

    How is skin cancer diagnosed?

    A skin examination by a dermatologist is the way to get a definitive diagnosis of skin cancer. In many cases, the appearance alone is sufficient to make the diagnosis.

    A skin biopsy is usually used to confirm a suspicion of skin cancer. This is performed by numbing the area under the tumor with a local anesthetic such as lidocaine. A small portion of the tumor is sliced away and sent for examination by a pathologist, who examines the tissue under a microscope and renders a diagnosis based on the characteristics of the tumor.

    What is the staging for skin cancer?

    There is no specific staging system for basal cell carcinoma. If the tumor is wider than 2 cm (about ¾ inch diameter), it is probably a more serious tumor. Basal cell carcinomas of the ears, nose, and eyelid may also be of more concern, regardless of the size.

    There is a staging system for squamous cell carcinoma. Tumors that are thicker than 2 mm, invade the nerve structures of the skin, occur on the ear, and have certain worrisome characteristics under the microscope are of more concern. If the tumor metastasizes away from the primary tumor, the cancer is upgraded to a very dangerous tumor.

    What is the treatment for skin cancer?

    There are several effective means of treating skin cancer. The choice of therapy depends on the location and size of the tumor, the microscopic characteristics of the cancer, and the general health of the patient.

    • Destruction by electrodessication and curettage (EDC): The tumor area is numbed with a local anesthetic and is scraped off with a sharp instrument (curette). The wound base is then cauterized with an electric needle. The advantage of this method is that it is fast, easy, and relatively inexpensive. The disadvantages are that the scar is often somewhat unsightly, and the recurrence rate is as high as 15%.
    • Surgical excision: The area around the tumor is numbed with a local anesthetic. A football-shaped portion of tissue including the tumor is then removed and then the wound edges are closed with sutures. For very big tumors, skin grafts or flaps are needed to close the defect. The advantages of this form of treatment are that there is a greater than 90% cure rate, the surgical specimen can be examined to be sure that the whole tumor is successfully removed, and the scar produced is usually more cosmetically acceptable than that of the EDC procedure. It is a more complicated procedure and is more expensive than EDC.
    • Mohs micrographic surgery: The site is locally anesthetized and the surgeon removes the visible tumor with a small margin of normal tissue. The tissue is evaluated under a microscope and areas that demonstrate residual microscopic tumor involvement are re-excised and the margins are re-examined. This cycle continues until no further tumor is seen. This more complicated and expensive option is the treatment of choice for tumors where normal tissue preservation is vital, where the tumor margins are poorly defined, in tumors that have been previously treated and have recurred, and in certain high-risk tumors.
    • Radiation therapy: Ten to fifteen treatment sessions deliver a high dose of radiation to the tumor and a small surrounding skin area. This form of treatment is useful in those who are not candidates for any surgical procedure. The advantage of radiation therapy is that there is no cutting involved. The disadvantages of this expensive alternative are that the treated area cannot be tested to be sure the whole tumor is gone and radiation scars look worse over time. It is for this reason it is usually reserved for elderly patients.

    What causes skin cancer?

    The exact cause of skin cancer is not known. It appears that basal cell cancers arise from basaloid cells in the upper layer of the skin. Uncontrolled growth of these cells is regulated by other factors in the skin. When that regulation is lost, skin cancer cells begin to grow into tumors.

    In squamous cell cancers, the tumors arise from a normal cell in the top layer of the skin, the epidermis. As with basal cell cancers, these cells are prevented from growing wildly by genetically controlled factors. When there is an alteration in the genes that regulate these cells, the control is lost and skin cancers start to grow. In many instances, the genes are altered by sunlight exposure.

    What are the different types of skin cancer?

    There are several different types of skin cancers:

    • Basal cell carcinoma is the most common cancer in humans. Over 1 million new cases are diagnosed in the U.S. each year. There are several different types of basal cell carcinoma, including the superficial type, the least worrisome variety; the nodular type, the most common; and the morpheaform, the most challenging to treat because the tumors often grow into the surrounding tissue (infiltrate) without a well-defined border.
    • Squamous cell carcinoma accounts for about 20% of all skin cancers but is more common in immunosuppressed people. In most instances, its biologic behavior is much like basal cell carcinoma, with minimal chance of spread. However, some of these tumors can act in an aggressive fashion and can even metastasize and cause death.
    • Less common skin cancers include melanoma, Merkel cell carcinoma, atypical fibroxanthoma, cutaneous lymphoma, and dermatofibrosarcoma.

    What are the signs and symptoms of skin cancer?

    Most basal cell carcinomas have few if any symptoms. Squamous cell carcinomas may be painful. Both types of skin cancer may appear as a sore that will not heal. There is often a slowly growing bump on the skin that may bleed after minor trauma. Basal cell carcinomas may have a pearly color while squamous cell carcinomas may have a thick scale on the surface. Both may have raised edges and a central ulceration.

    When is a mole dangerous or high-risk for becoming a skin cancer?

    Moles are almost always harmless and only very rarely turn into skin cancer. If a mole becomes cancerous, it would be a melanoma. There is a precancerous stage, called a dysplastic nevus, that is somewhat more irregular than a normal mole. Moles never become squamous cell carcinomas or basal cell carcinomas.

    What are the most common sites where skin cancer develops?

    Skin cancers typically arise in areas of the skin exposed to the sun repeatedly over many years such as the face, ears, back of the neck, and the bald area of the scalp. Less commonly, these tumors may appear at sites with only limited sun exposure such as the back, chest, or the extremities. However, skin cancer may occur anywhere on the skin.

    How is skin cancer diagnosed?

    A skin examination by a dermatologist is the way to get a definitive diagnosis of skin cancer. In many cases, the appearance alone is sufficient to make the diagnosis.

    A skin biopsy is usually used to confirm a suspicion of skin cancer. This is performed by numbing the area under the tumor with a local anesthetic such as lidocaine. A small portion of the tumor is sliced away and sent for examination by a pathologist, who examines the tissue under a microscope and renders a diagnosis based on the characteristics of the tumor.

    What is the staging for skin cancer?

    There is no specific staging system for basal cell carcinoma. If the tumor is wider than 2 cm (about ¾ inch diameter), it is probably a more serious tumor. Basal cell carcinomas of the ears, nose, and eyelid may also be of more concern, regardless of the size.

    There is a staging system for squamous cell carcinoma. Tumors that are thicker than 2 mm, invade the nerve structures of the skin, occur on the ear, and have certain worrisome characteristics under the microscope are of more concern. If the tumor metastasizes away from the primary tumor, the cancer is upgraded to a very dangerous tumor.

    What is the treatment for skin cancer?

    There are several effective means of treating skin cancer. The choice of therapy depends on the location and size of the tumor, the microscopic characteristics of the cancer, and the general health of the patient.

    • Destruction by electrodessication and curettage (EDC): The tumor area is numbed with a local anesthetic and is scraped off with a sharp instrument (curette). The wound base is then cauterized with an electric needle. The advantage of this method is that it is fast, easy, and relatively inexpensive. The disadvantages are that the scar is often somewhat unsightly, and the recurrence rate is as high as 15%.
    • Surgical excision: The area around the tumor is numbed with a local anesthetic. A football-shaped portion of tissue including the tumor is then removed and then the wound edges are closed with sutures. For very big tumors, skin grafts or flaps are needed to close the defect. The advantages of this form of treatment are that there is a greater than 90% cure rate, the surgical specimen can be examined to be sure that the whole tumor is successfully removed, and the scar produced is usually more cosmetically acceptable than that of the EDC procedure. It is a more complicated procedure and is more expensive than EDC.
    • Mohs micrographic surgery: The site is locally anesthetized and the surgeon removes the visible tumor with a small margin of normal tissue. The tissue is evaluated under a microscope and areas that demonstrate residual microscopic tumor involvement are re-excised and the margins are re-examined. This cycle continues until no further tumor is seen. This more complicated and expensive option is the treatment of choice for tumors where normal tissue preservation is vital, where the tumor margins are poorly defined, in tumors that have been previously treated and have recurred, and in certain high-risk tumors.
    • Radiation therapy: Ten to fifteen treatment sessions deliver a high dose of radiation to the tumor and a small surrounding skin area. This form of treatment is useful in those who are not candidates for any surgical procedure. The advantage of radiation therapy is that there is no cutting involved. The disadvantages of this expensive alternative are that the treated area cannot be tested to be sure the whole tumor is gone and radiation scars look worse over time. It is for this reason it is usually reserved for elderly patients.

    Source: http://www.rxlist.com

    Most basal cell carcinomas have few if any symptoms. Squamous cell carcinomas may be painful. Both types of skin cancer may appear as a sore that will not heal. There is often a slowly growing bump on the skin that may bleed after minor trauma. Basal cell carcinomas may have a pearly color while squamous cell carcinomas may have a thick scale on the surface. Both may have raised edges and a central ulceration.

    Source: http://www.rxlist.com

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