What Is Skin Cancer?
Reviewed by: HU Medical Review Board | Last reviewed: May 2017. | Last updated: May 2019
Each year, more cases of skin cancer are diagnosed than breast, prostate, lung, and colon cancers combined.1 This makes skin cancer the most common cancer in the United States, affecting nearly 3.4 million Americans annually.2,3
Types of skin cancer
There are three main types of skin cancer:
- Basal cell carcinoma
- Squamous cell carcinoma
Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are commonly grouped together as “non-melanoma skin cancer.” Non-melanoma skin cancer is far more common than melanoma, but melanoma is considered more dangerous. Most melanomas are superficial and surgically curable but are more likely to spread (metastasize) to other parts of the body. For this reason, 75% of skin cancer deaths are related to melanoma.4
Fortunately, most skin cancers can be treated and removed when they are caught early. More than 91% of people are still alive 5 years after being diagnosed with melanoma.5
Treatment of all skin cancers can lead to scars. Having skin cancer can decrease quality of life and productivity.6
Risk factors and prevention
The most important modifiable risk factor for skin cancer is exposure to ultraviolet (UV) light. UV light comes from the sun and tanning beds. UV radiation has been called a carcinogen or cancer-causing substance.7 UV rays can damage the DNA in skin cells, which may cause harmful genetic mutations. Cancer develops when these harmful mutations lead to uncontrolled cell growth.
You can reduce your UV exposure and risk of skin cancer by:
- Using a broad spectrum sunscreen with sun protection factor (SPF) 15 or higher.
- Seeking shade between 10 am and 2 pm.
- Wearing long sleeves, long pants, wide-brimmed hats, and sunglasses.
- Avoiding indoor tanning beds.
Some skin cancer risk factors are things that you cannot change.8,9 These include:
- Skin color
- Age and gender
- Family history of melanoma
- Presence of multiple moles or atypical moles. Atypical moles may be larger than other moles, with an abnormal color or shape.
- Inherited medical conditions such as xeroderma pigmentosum, basal cell nevus syndrome, or familial atypical multiple mole-melanoma syndrome.
Not everyone with these risk factors will develop skin cancer. However, if you are at high risk, you may be able to take steps to detect precancer that may turn into cancer–or early signs of cancer. Experts recommend regular skin self-examination. Self-examination will help you to become familiar with your moles, freckles, and blemishes.9 If you notice changes, discuss them with your doctor. Your primary care doctor might also recommend regular follow-up with a dermatologist if you are at high risk.
As a first step in diagnosing skin cancer, your doctor will want to understand your medical history and do a physical examination.8,9 Your doctor will ask when you first noticed a mark on your skin and how it has changed. Mention any symptoms such as pain, itching, bleeding, or oozing. Your doctor might ask about your sun exposure, sun protective behaviors, and family history of skin cancer.
Your doctor will examine the questionable mark on your skin and check for any other suspicious lesions.8,9 She or he may use a special magnifying lens called a dermatoscope. The dermatoscope allows your doctor to see the features of the lesion better. Your doctor may feel your lymph nodes. Lymph nodes that feel lumpy may be a sign that the cancer has spread.
A skin biopsy is a sample of tissue that is removed and sent to a lab. In the lab, the sample will be studied under a microscope to see whether it contains cancer cells.
If your doctor is concerned that the skin cancer might have spread, you may need additional tests. This is rare with non-melanoma skin cancer or early stage melanoma.8,9 A lymph node biopsy involves taking a small amount of tissue from the lymph node closest to the melanoma skin tumor to look for cancer cells. Imaging tests may be done to look for melanoma that has spread to lymph nodes or distant organs.
The results of these tests are used to stage the skin cancer. The cancer stage indicates how widespread the cancer is.8,9
Treatment for skin cancer depends on the skin cancer type, location, size, risk that the cancer returns, and stage.8-11
AK, actinic keratosis; BCC, basal cell carcinoma; SCC, squamous cell carcinoma