Understanding Skin Cancer
Young Ju, Ph.D.
During the summer months, tennis players are more often outside for extended periods of time for training and matches and thus likely exposed to higher UV intensity, which could increase the risk of skin cancer. Skin cancer by definition is the uncontrolled growth of abnormal skin cells and is the most common type of cancer. One in five Americans is likely to develop skin cancer by the age of 70; an estimated 97,610 new skin cancer cases will be diagnosed in 2023 (1).
Types of Skin Cancer (1, 2)
Figure 1
Most skin cancers start in the epidermis, the top layer of skin (Figure 1).
Figure 1. Structure of the skin (1)
Skin cancer can be classified as non-melanoma or melanoma. Non-melanoma skin cancer refers to cancer that forms in the basal cells and squamous cells. This cancer type affects ~3.6 million Americans each year.
Basal cell carcinoma is the most common type of skin cancer (~66% of skin cancers):
Usually develops on sun-exposed areas on the skin, e.g., face, head, neck, shoulder, arms, and legs.
Tends to grow slowly.
Very rarely spreads to other parts of the body. (But if left untreated, basal cell cancer can grow into nearby areas and invade the bone or other tissues.)
Squamous cell carcinoma affects ~1.8 million Americans each year (~33% of skin cancers).
Often develops inside the body (e.g., mouth, throat or lungs), but it is not limited to that area.
Melanoma skin cancer is much less common than non-melanoma but more likely to invade nearby tissue and spread to other parts of the body. This cancer develops in the melanocytes–the cells that produce a pigment called melanin. Over 1 million Americans are living with melanoma. Invasive melanoma is the fifth most common cancer both among men and women.
Symptoms (1, 2)
Symptoms can appear at any point, and vary greatly depending on the type of skin cancer, stage, and its location on the skin. Skin cancer symptoms may include:
A new spot or a change in the size, shape or color of an existing spot on the skin
An itchy or painful spot
A non-healing sore with a crust or bleeding
A reddish shiny bump
A rough or scaly spot
A growth with a raised border and central crust or bleeding
A wart-like growth
A scar-like growth with irregular border
Risk Factors (1, 2)
The following factors may increase risk for skin cancer:
Excess unprotected sun exposure or exposure to other ultraviolet (UV) radiation: more than 95% of all skin cancers are caused by UV exposure; other UV sources are indoor tanning, welding, and glue curing lights for artificial nails, etc.
Fair skin color, blonde or red hair, freckles, blue eyes and/or a tendency to sunburn; people with fair skin color have less melanin that helps protect from the sun.
Moles (more than 50), or irregular-shaped moles: moles are not cancerous or dangerous, unless the DNA in moles get damaged/mutated.
A personal or family history of skin cancer
A weakened immune system
Use of immunosuppressants which can exacerbate UV-induced DNA damage
Previous serious skin injuries, e.g., major scar or burn
Certain skin conditions such as non-cancerous lesions like sunspots or age spots.
Carrying certain genes (3): about 5-10% of melanoma cases are caused by genetic factors. A genetic test cannot tell whether you will develop skin cancer, but it can help a dermatologist/physician monitor any signs of skin cancer.
Screening & Diagnosis (1, 4)
When there are persisting, changing, or abnormal spots on the skin, tests are available to check or confirm skin cancer. A visual exam by a health care provider checks suspicious spots for color, size, shape, and texture. A skin biopsy may be done to confirm that it is or is not cancerous and to determine whether to remove it or monitor it. Additional imaging tests may be included to check nearby tissues. Also the patient can perform regular skin checks.
Once confirmed by tests, skin cancer can be defined as Stage 0, I, II, III, or IV based on the size of the tumor (T), spread to nearby lymph nodes (N), and spread (metastasized) to distant parts of the body (M). Stage I cancers are small and limited to the area where they began. Stage IV indicates advanced cancer that has spread to other areas of the body.
While the U.S. Preventive Service Task Force does not recommend regular screening for skin cancer, the American Cancer Society recommends people between the ages of 20 and 40 get a professional skin exam every 3 years. The National Comprehensive Cancer Network recommends a biannual or annual complete skin exam for the first 5 years after a suspicious skin spot is detected.
Treatments
If there is a skin cancer diagnosis, the health care team will strategize the best treatment options, orders, and combinations with the patient based on stage, the location of the tumor, speed of the tumor growth, behavior of the cancer cells, severity of symptoms caused by the tumor, patient’s age and health condition, chance of cancer cure, and possible side effects of treatments, etc. These treatments may include surgical excision (5), local treatment of targeted surface layer of the skin (6), radiation therapy, chemotherapy, targeted use of cancer cell-growth inhibiting drugs (7, 8), and immunotherapy. Immunotherapy stimulates the patients’ immune system to recognize and destroy cancer cells.
All of these treatments have side effects which should be discussed with your health care team.
Survival Rates (1, 2, 9)
Non-melanoma skin cancers are highly treatable if detected early and treated properly. For melanoma skin cancers, if the tumor has not not spread to nearby lymph nodes, the rate of melanoma patients who will survive 5 years after diagnosis is ~99%. If it has spread to nearby lymph nodes, it’s ~68%. And if it spreads to distant lymph nodes and other organs, it’s ~30%.
Prevention (1, 2, 9)
You can check the UV Index from the UV forecast to help avoid harmful exposure (10). For example, if the index is greater than 3, protection is needed. If it’s greater than 8, extra protection is needed. Here are some common sense measures to help prevent skin cancer:
Avoid excessive sun exposure all year, not just during the summer.
Use sunscreen (with a minimum SPF 30) and protective clothing (with UV protection factor).
Avoid tanning beds.
Make regular skin self-exams: Everyone should check the skin regularly and look for suspicious spots, and any signs of melanoma using the ABCDE method (A for asymmetrical shape, B for irregular borders, C for color, D for diameter larger than 6 mm, and E for evolving size, shape, and color). Report any of these changes to your doctor.
Overall
Most skin cancer cases are lifestyle diseases. Skin cancer is highly preventable. If detected early and treated properly, the survival rate is high. While not all skin changes lead to skin cancer, you should talk to your doctor if you notice any changes on the skin. Your doctor or dermatologist will examine the skin changes to determine if it’s skin cancer.
Dr. Young Ju is a Ph.D and Associate Professor of Human Nutrition, Foods, and Exercise at Virginia Tech.
REFERENCES
1. American Cancer Society. https://www.cancer.org/cancer/types/basal-and-squamous-cell-skin-cancer/about/what-is-basal-and-squamous-cell.html
Centers for Disease Control and Prevention. Skin Cancer. https://www.cdc.gov/cancer/skin/index.html
3. Genetics of Skin Cancer–Health Professional Version. https://www.cancer.gov/types/skin/hp/skin-genetics-pdq#_1004
4. Centers for Disease Control and Prevention. What Screening Tests Are There? https://www.cdc.gov/cancer/skin/basic_info/screening.html
5. American Cancer Society. Surgery for Basal and Squamous Cell Skin Cancers. https://www.cancer.org/cancer/types/basal-and-squamous-cell-skin-cancer/treating/surgery.html
6. American Cancer Society. Local Treatments Other Than Surgery for Basal and Squamous cell skin cancers. https://www.cancer.org/cancer/types/basal-and-squamous-cell-skin-cancer/treating/other-than-surgery.html
7. American Cancer Society. Targeted Therapy Drugs for Melanoma Skin Cancer. https://www.cancer.org/cancer/types/melanoma-skin-cancer/treating/targeted-therapy.html
8. American Cancer Society. Targeted Therapy for Basal and Squamous Cell Skin Cancer. https://www.cancer.org/cancer/types/basal-and-squamous-cell-skin-cancer/treating/targeted-therapy.html
9. National Cancer Institute. PDQ® Cancer Information for Health Professionals. https://www.cancer.gov/publications/pdq
10. US Environmental Protection Agency. A Guide to the UV Index. https://www.epa.gov/sites/default/files/documents/uviguide.pdf
People with any health problems should talk to their healthcare providers. This information is provided for your reference and you use at your own risk; you should rely on your medical professional for medical advice.
