The Farber Center: For Radiation Oncology

Skin cancer is a disease in which skin cells lose the ability to divide and grow normally. Healthy skin cells normally divide in an orderly way to replace dead cells and grow new skin. Abnormal cells can grow out of control and form a mass or 'tumor'. When abnormal cells originate in the skin, the mass is called a skin tumor. A skin tumor is considered benign if it is limited to a few cell layers and does not invade surrounding tissues or organs. But if the tumor spreads to surrounding tissues it is considered malignant or cancerous. The three most common skin cancers are basal cell cancer, squamous cell cancer, and melanoma, each of which is named after the type of skin cell from which it arises.
The mechanism that generates the first two forms is different from the mechanism that generates melanoma. The direct DNA damage is responsible for BCC and SCC while the indirect DNA damage causes melanoma. the mortality rate of BCC and SCC is around 0.3% causing 2000 deaths per year in the US. In comparison the mortality rate of melanoma is 15-20% and it causes 6500 deaths per year. Even though it is much less common than BCCs and SCCs, malignant melanoma is responsible for 75% of all skin cancer-related deaths.

There are a variety of different skin cancer symptoms.

Basal cell carcinoma usually presents as a raised, smooth, pearly bump on the sun-exposed skin of the head, neck or shoulders. Sometimes small blood vessels can be seen within the tumor. Crusting and bleeding in the center of the tumor frequently develops. It is often mistaken for a sore that does not heal. This form of skin cancer is the least deadlyand with proper treatment can be completely eliminated, often without scarring. Superficial basal cell carcinomas often appear on the chest or back and look more like patches of raw, dry skin.

Squamous cell carcinoma is commonly a red, scaling, thickened patch on sun-exposed skin. Some are firm hard nodules and dome shaped like keratoacanthomas. Ulceration and bleeding may occur. When SCC is not treated, it may develop into a large mass. Squamous cell is the second most common skin cancer. It is dangerous, but not nearly as dangerous as a melanoma.

Most melanomas are brown to black looking lesions. Unfortunately, a few melanomas are pink, red or fleshy in color; these are called amelanotic melanomas. These tend to be more aggressive. Warning signs of malignant melanoma include change in the size, shape, color or elevation of a mole. Other signs are the appearance of a new mole during adulthood or new pain, itching, ulceration or bleeding.

Merkel cell carcinomas are most often rapidly growing, non-tender red, purple or skin colored bumps that are not painful or itchy. They may be mistaken for a cyst or other type of cancer

Risk Factors

People with certain risk factors are more likely than others to develop skin cancer. Risk factors vary for different types of skin cancer, but some general risk factors are:

Skin Color: Lighter natural skin color. If you have blond or red hair and light-colored eyes, and you freckle or sunburn easily, you're much more likely to develop skin cancer than is a person with darker skin.

Family history: If one of your parents or a sibling has had skin cancer, you may have an increased risk of the disease.

History of Sunburns: Every time you get sunburned, you damage your skin cells and increase your risk of developing skin cancer. After a sunburn, your body works to repair the damage. Having multiple blistering sunburns as a child or teenager increases your risk of developing skin cancer as an adult.

Moles: People who have many moles or abnormal moles called dysplastic nevi are at increased risk of skin cancer. These abnormal moles — which look irregular and are generally larger than normal moles — are more likely than others to become cancerous. If you have a history of abnormal moles, watch them regularly for changes

A weakened immune syste: People with weakened immune systems have a greater risk of developing skin cancer. This includes people living with HIV/AIDS or leukemia and those taking immunosuppressant drugs after an organ transplant

To determine if the lesion is cancerous or not, the doctor or nurse will usually first discuss your medical history to determine your risk factors, including the history of skin cancer in your family and the number of prior sunburns. A skin examination will follow, during which the doctor will note the size, shape, color, and texture of the suspicious area. He or she will then examine your lymph glands to check for swelling, a potential sign of cancer. The only way to definitively diagnose the various types of skin cancer is to biopsy suspicious-looking lesions. Useful information, such as tumor depth, can only be obtained by biopsy. Biopsy methods include:

Shave biopsy: The doctor uses a thin, sharp blade to shave off the abnormal growth. This is the most common form of biopsy when the doctor suspects a basal cell carcinoma or squamous cell carcinoma.

Punch biopsy: The doctor uses a sharp, hollow tool to remove a circle of tissue from the abnormal area.

Incisional biopsy: The doctor uses a scalpel to remove part of the growth.

Excisional biopsy: The doctor uses a scalpel to remove the entire growth and some tissue around it. Note that excisional biopsy is the ideal biopsy choice when a doctor suspects a melanoma. Depending on the size or location of the tumor, however, an excisional biopsy may not always be possible.

Staging of basal cell or squamous cell carcinoma

Stage 0:
Carcinoma in situ that is confined to the epidermis - the top layer of the skin (see Skin Anatomy). Squamous cell carcinoma in situ - also known as Bowen's disease - is the first stage of squamous cell skin cancer.

Stage 1:
Small tumor that is less than 2 centimeters in size and has not spread to the lymph nodes or other organs.

Stage 2:
Tumor that is larger than 2 centimeters, but has not spread to the lymph nodes or other organs.

Stage 3:
Tumor that has metastasized (spread) to the tissues under the skin (muscle, bone, or cartilage) and/or to the regional (nearby) lymph nodes.

Stage 4:
Tumor of any size that has metastasized (spread) to distant organs such as the lungs or brain.

Staging for Melamona

The AJCC staging system is based on three sets of criteria: how thick the tumor is (T), the extent to which it has spread to the lymph nodes (N), and the extent to which it has metastasized to other parts of the body (M). The AJCC staging system is outlined below, with the TNM parameters and corresponding Clark's level in parentheses. The TNM levels are explained following the outline of the staging system. The AJCC and the Clark's level stages do not always correspond, and when they don't, the AJCC system should always take precedence.

Stage 0
This is melanoma in situ, meaning the cancer is in the epidermis and has not begun to spread yet. (Clark's level I)

Stage IA
Localized melanoma that is less than 0.75 mm (Clark's level II: the tumor has spread to the upper dermis; T1N0M0).

Stage IB
Localized melanoma that is thicker than 0.75 mm but less than 1.5 mm (Clark's level III: the tumor involves most of the upper dermis); T2N0M0).

Stage IIA
Localized melanoma that is thicker than 1.5 mm but less than 4 mm (Clark's level IV: the tumor has spread to the lower dermis; T3N0M0).

Stage IIB
Localized melanoma that is greater than 4 mm (Clark's level V: the tumor has spread beneath the dermis; T4N0M0).

Stage III
The melanoma has spread to nearby lymph nodes or less than 5 in-transit metastases are found. An in-transit metastasis is metastasis that is located between the primary tumor and the closest lymph node region. It results from melanoma cells getting trapped in the lymphatic channels (any T, N1M0).

Stage IV
The tumor has metastasized to other parts of the body (any T, any N, M1 or M2).

TNM levels
Thickness of the primary tumor (T):

T1:
The tumor is 0.75 mm or less in thickenss and invades the upper dermis.

T2:
The tumor is more than 0.75 mm but not more than 1.5 mm in thickness and/or begins to invade the lower dermis.

T3:
The tumor is more than 1.5 mm but not more than 4 mm in thickness and/or invades the lower dermis.

T3a:
The tumor is more than 1.5 mm but not more than 3 mm in thickness.

T3b:
The tumor is more than 3 mm but not more than 4 mm in thickness.

T4:
The tumor is more than 4 mm in thickness and/or invades the subcutaneous tissue (the tissue beneath the skin) and/or satellites within 2 cm of the primary tumor.

T4a:
The tumor is more than 4 mm in thickness and/or invades the subcutaneous tissue.

T4b:
The tumor satellites within 2 cm of the primary tumor.

Involvement of The Regional Lymph Nodes (N)

NX:
The regional lymph nodes cannot be assessed.

N0:
There is no regional lymph node metastasis.

N1:
Metastasis is 3 cm or less in greatest dimension in any regional lymph node(s).

N2:
Metastasis is more than 3 cm in greatest dimension in any regional lymph node(s) and/or there is in-transit metastasis. An in-transit metastasis is one that is located between the primary tumor and the closest lymph node region. It results from melanoma cells getting trapped in the lymphatic channels.

N2a:
Metastasis is more than 3 cm in greatest dimension in any regional lymph node.

N2b:
There is in-transit metastasis.

N2c:
Both N2a and N2b.

Extent of Distant Metastasis (M)

MX:
Distant metastasis cannot be assessed.

M0:
There is no distant metastasis.

M1:
Distant metastasis is present.

M1a:
Metastasis is in the skin or subcutaneous tissue or lymph node(s) beyond the regional lymph nodes.

M1b:
Metastasis occurs in other parts of the body.

TREATMENT OPTIONS FOR NONMELANOMA SKIN CANCER
Treatment of basal cell carcinoma and squamous cell carcinoma may include the following:

RADIATION THERAPY
Temporary (high dose rate, or HDR) brachytherapy: This newer technique offered by The Farber Center compared to conventional external beam radiotherapy (EBRT), the radiation can be more precisely targeted. This minimizes damage to surrounding tissues. Read more about the principles of brachytherapy. High dose rate (HDR) brachytherapy is an alternative treatment option to the surgical removal of skin cancer. HDR brachytherapy not only provides good cosmetic results but has also been shown to be highly effective in preventing the skin cancer from returning. HDR brachytherapy is equally as effective as EBRT, but can be completed in a much shorter time. Treatment can be completed in a short space of time, usually over the course of 1–2 times a week for up to 4 weeks. Treatment is given on an outpatient basis. This means you will not need an overnight stay in hospital. Brachytherapy is therefore a very convenient form of radiotherapy treatment.

Here is an example of a squamous cell carcinoma before and after radiation treatment:

MOHS SURGERY
Mohs micrographic surgery. Mohs micrographic surgery is a minor surgical procedure and special method of removing skin cancers using local anesthesia (numbing). The majority of cases are performed in the physician's office. Mohs is a very precise, highly detailed technique whereby small layers of skin are sequentially removed and immediately examined under the microscope until the samples indicate that the skin cancer is completely removed. The procedure uses frozen sections of skin that are then stained with special dyes. The dyed frozen pieces of skin are further examined under the microscope and a tumor map is drawn by the Mohs surgeon. The freezing process allows an immediate examination of the entire tumor margin and tissue histology (microscopic examination of cells).

SIMPLE EXCISION
Removal by surgery.

CRYOSURGERY
A procedure in which tissue is frozen to destroy abnormal cells. Liquid nitrogen or liquid carbon dioxide is used to freeze the tissue. Also called cryoablation and cryosurgical ablation.

LASER THERAPY
A surgical procedure that uses the cutting power of a laser beam to make bloodless cuts in tissue or to remove a surface lesion such as a tumor.

TOPICAL CHEMOTHERAPY
Treatment with anticancer drugs in a lotion or cream applied to the skin.

PHOTODYNAMIC THERAPY
Treatment with drugs that become active when exposed to light. These activated drugs may kill cancer cells.

ELETRODESICCATION AND CURETTAGE
The drying of tissue by a high-frequency electric current applied with a needle-shaped electrode. Curettage is the removal of tissue with a curette (a spoon-shaped instrument with a sharp edge).

TREATMENT OPTIONS FOR MELANOMA SKIN CANCER
treatment options depend on the following: The thickness of the tumor and where it is in the body. How quickly the cancer cells are dividing. Whether there was bleeding or ulceration at the primary site. Whether cancer has spread to the lymph nodes or to other places in the body. The number of places cancer has spread to in the body and the level of lactate dehyrogenase (LDH) in the blood. The patient's general health. Treatment will be based on staging and may include Chemotherapy, Biological and Radiation Therapy.