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Skin Cancer

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Prevention of skin cancer

Types of skin cancer

The most common type of skin cancer is also the least dangerous: basal cell carcinoma. This is followed in incidence by squamous cell carcinoma.

Here is a link to a great site by the American Cancer Society with lots of information, videos, and photos for various types of skin cancer.

squamous cell carcinoma of the skin

Squamous-cell skin cancer, also known as cutaneous squamous-cell carcinoma (cSCC), is one of the most common types of skin cancer along with basal cell cancer, and melanoma. It usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months. Squamous-cell skin cancer is not very likely to spread to distant anatomic sites except when large or aggressive.  When confined to the outermost layer of the skin, a precancerous or in situ form of cSCC is known as Bowen's disease.

The greatest risk factor is high total exposure to ultraviolet radiation, which is often from the Sun or tanning beds. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen's disease, arsenic exposure, radiation therapy, poor immune system function, previous basal cell carcinoma, and HPV infection. Risk from UV radiation is related to total (cumulative) exposure, rather than early exposure. It begins from squamous cells found within the skin. Diagnosis is often based on skin examination and confirmed by tissue biopsy. Imaging studies (e.g., a CT scan) are used in cases where extensive disease is suspected. Cancer staging is a way of approximating risk, and ranges from lowest risk (stage I) to greatest risk (stage IV). Treatment is usually with surgical removal, but may also be accomplished with radiation therapy. In advanced cancers, multiple modalities of treatment are often employed to attain better cure rates, and this may include surgery, radiation, chemotherapy, and/or immunotherapy in various orders and sometimes concurrently (such as radiation and chemotherapy simultaneously).

basal cell carcinoma

Basal cell carcinoma (BCC), also known as basal cell cancer, is the most common type of skin cancer. It often appears as a painless raised area of skin, which may be shiny with small blood vessels running over it.  It may also present as a raised area with ulceration. Basal-cell cancer grows slowly and can damage the tissue around it, but it is unlikely to spread to distant areas or result in death. Occasionally, a cancer can have microscopic features of both basal cell carcinoma and squamous cell carcinoma, and these behave like squamous cell carcinoma.

Risk factors include exposure to ultraviolet light, having lighter skin, radiation therapy, long-term exposure to arsenic and poor immune-system function.  Exposure to UV light during childhood is particularly harmful. Tanning beds have become another common source of ultraviolet radiation. Diagnosis often depends on skin examination, confirmed by tissue biopsy.

It remains unclear whether sunscreen affects the risk of basal-cell cancer. Treatment is typically by surgical removal.  Other options for small basal cell carcinomas or for patients who cannot undergo surgery include electrodesiccation and curettage, cryosurgery, topical chemotherapy, photodynamic therapy, laser surgery or the use of imiquimod, a topical immune-activating medication.

Basal-cell cancer accounts for at least 32% of all cancers globally. In the United States, about 35% of white males and 25% of white females are affected by BCC at some point in their lives.

MELANOMA

Melanoma, also known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes.  Melanomas typically occur in the skin but may rarely occur in the mouth, lining of the sinuses or nose, intestines or eye.  In women, they most commonly occur on the legs, while in men they most commonly occur on the back. About 25% of melanomas develop from moles. Changes in a mole that can indicate melanoma include an increase in size, irregular edges, change in color, itchiness or skin breakdown.

The primary cause of melanoma is ultraviolet light (UV) exposure in those with low levels of the skin pigment melanin. The UV light may be from the sun or other sources, such as tanning devices. Those with many moles, a history of affected family members and poor immune function are at greater risk. A number of rare genetic conditions such as xeroderma pigmentosum also increase the risk.  Diagnosis is by biopsy and analysis of any skin lesion that has signs of being potentially cancerous. Note of any surface ulceration before biopsy is meaningful for staging, and the biopsy of choice is a full thickness skin “punch” biopsy so that the depth of the lesion may be measured.

Using sunscreen and avoiding UV light may prevent melanoma.  Treatment is typically removal by surgery.  In those with slightly larger cancers, nearby lymph nodes may be tested for spread (metastasis). Most people are cured if spread has not occurred. For those in whom melanoma has spread, immunotherapy, biologic therapy, radiation therapy or chemotherapy may improve survival.  With treatment, the five-year survival rates in the United States are 99% among those with localized disease, 65% when the disease has spread to lymph nodes and 25% among those with distant spread. The likelihood that melanoma will reoccur or spread depends on its thickness, how fast the cells are dividing and whether or not the overlying skin has broken down (ulcerated).

Melanoma is the most dangerous type of skin cancer. Globally, in 2012, it newly occurred in 232,000 people.  In 2015, there were 3.1 million people with active disease, which resulted in 59,800 deaths.  Australia and New Zealand have the highest rates of melanoma in the world.  There are also high rates in Northern Europe and North America, while it is less common in Asia, Africa and Latin America.  In the United States melanoma occurs about 1.6 times more often in men than women. Melanoma has become more common since the 1960s in areas mostly populated by people of European descent.

• This link goes to the American Cancer Society interactive website with text and diagrams on melanoma skin cancer.

• Here is an article from the American Academy of Dermatology describing how to perform a self-exam of your skin and what findings are suspect for melanoma.

• This YouTube video by the American Cancer Society explains sentinel lymph node biopsy for melanoma.

Merkel cell carcinoma

• Merkel cell carcinoma is an uncommon type of skin cancer mostly found on the cheeks of an individual of greater than 75 years of age. It behaves aggressively like melanoma, but is more responsive to radiation than melanoma.

• This link goes to the American Cancer Society interactive website on Merkel cell cancer with illustrations and text.

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