Fundamentals of Skin Cancer and its Prevention

Skin cancer and statistics

Skin cancer is one of the most common cancers and is classified as non-melanoma skin cancer (NMSC) or melanoma. Non-melanoma skin cancers such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) arise from keratinocyte cells.1 Melanoma is originated from melanocytes in the skin that produce brown pigment of the skin. Merkel cell cancer, Kaposi's sarcoma, cutaneous lymphoma, adnexal skin cancer, and other types of sarcomas account for less than 1% of all skin cancers.2

Skin cancer is one of the most common cancers in the US, with more cases diagnosed each year than all other cancers combined, including colon, lung, prostate and breast cancers. According to the American Academy of Dermatology, over 2 million people in the United States are diagnosed with basal cell carcinoma or squamous cell carcinoma per year, and having one form of skin cancer increases the chance of developing another. Basal cell carcinoma is common in Japanese, Chinese, Hispanics, Caucasians and the most prevalent type of skin cancer in the United States, with more than 3.6 million cases are diagnosed each year, making it the most common type of cancer in the US.3 However, deaths from basal cell carcinoma are uncommon, with about 3,000 people dying from the cancer per year. Basal cell carcinoma most often occurs in sun-exposed areas of the skin, including the back, neck, scalp, face, arms, and hands, but it may also occur in areas of the skin that are not exposed to the sun. On the other hand, more than 1 million cases of squamous cell carcinoma are diagnosed each year in the United States, with around 15,000 people dying from this type of skin cancer. Squamous cell carcinoma is common in Asian-Indians, African-Americans and most often found in areas of the body that are exposed to the sun on a regular basis, but it can also be found in areas that are less exposed to the sun, such as the lips, mouth and genitals.4

Melanoma is the most dangerous form of skin cancer because it occurs in the melanocytes that cause moles and initially appears to be harmless moles. Although the American Cancer Society estimates that melanoma is less common than non-melanoma skin cancers and accounts for only 1 percent of skin cancer cases, it accounts for the vast number of deaths.5

According to American Cancer Society, fifty percent of Americans are likely to have basal cell carcinoma or squamous cell carcinoma at least once in their lives, and are more likely to develop skin cancer as they get older and the average age at the time of diagnosis was sixty-three years old. Melanoma is twice as common in young women as in men, and twice as common in men over 60 years of age than women.5 According to the American Cancer Society, Caucasians are more likely than Africans to develop skin cancers, and non-Hispanic Caucasians (2.6 percent) have a higher lifetime risk of melanoma than Hispanics (0.58 cents) and African-Americans (0.1%).5

Cancers of the skin are caused by mutations in the DNA, which cause the unchecked growth of skin cells and cause cancer. Basal cell carcinoma and squamous cell carcinoma are caused by ultraviolet light, which damages the DNA and causes abnormal cell division. Some forms of human papillomavirus may cause squamous cell carcinoma, and it can also be triggered by prolonged exposure to carcinogenic chemicals. The majority of moles do not progress to melanoma, and the cause of melanoma is unknown.

Risk factors of skin cancer

Many of the following factors increase the risk of skin cancer6:

• having a history of skin cancer in family
• exposure to chemical substances including radium, pitch, arsenic, creosote
• exposure to radiation, during some acne or eczema treatments
• exposure to UV rays from the tanning booths, tanning lamps, sun that is unnecessary or unprotected
• living or having vacation in warm, sunny climates
• working outside on a regular basis
• having had serious sunburns in the past
• having a mole that is numerous, irregular, or large
• having a freckled or pale complexion
• having sun-sensitive skin that doesn't tan or sunburns easily
• having hair that is naturally red or blond
• having green, hazel or blue eyes
• having precancerous growths on the skin
• having a weakened immune system, such as from human immunodeficiency virus
• Patients who had undergone organ transplantation
• Patients who are taking immunosuppressive drugs

Signs and symptoms

Early detection of melanoma or skin cancer greatly improves the likelihood of successful treatment. While not all skin cancers are alike and many signs aren't always present, being aware of irregular changes in the skin will aid in early detection of skin cancer. Melanoma most often affects women's legs and men's trunks. It can appear on any part of the body, including places that aren't exposed to the sunlight. Skin cancer is diagnosed by looking for new moles and spots, as well as variations in the size and color of current moles. The first five letters of the Latin alphabet help to recognize the warning signs.7

A is an asymmetry.

The majority of melanomas are asymmetrical. The symmetry between the two sides would be different if you draw a line between the spots on the skin. With round and oval symmetry, it does not resemble a typical mole.

B is the border.

Melanoma has an irregular surface with bumps, while normal moles have a smooth surface.

C is the color.

The fact that many colors are mixed is a warning sign. Brown is the most common color for non-malignant moles and change in color is a sign of melanoma.

D is the diameter and dark color.

Melanoma may be detected early if the mole is 6 mm in diameter or greater. Dark shades are also regarded as a warning sign and a colorless amelanotic melanoma is a rare form of melanoma.

E is for evolving.

Early signs of melanoma include changes in the size, shape, colour, diameter, bleeding, and scratching of skin spots.

Skin cancer prevention

To avoid skin cancer, it is not necessary to avoid the sun entirely, but it is advisable to follow the guidelines below8:

- Ultraviolet A rays and Ultraviolet B rays are stronger between 10am-4pm, so avoid the sun during this period.

- If you must be outside for an extended period while the sun's ultraviolet rays are at their peak, try to stay in the shade.

- At any time of the day, apply sunscreen to the affected area of the skin and apply a sunscreen with an SPF of 30.

- Reapply sunscreen every two hours, and more often if you're swimming or sweating.

- Hats should be worn to protect the face from the sun's UV rays, and wide-brimmed hats are more appropriate.

- Even the eyes need to be protected from the sunlight, so use sunglasses that block ultraviolet A and ultraviolet B rays and wear them to cover your eyes and the skin around the eyes.

- Regular medical check-ups and skin examinations may aid in the early detection and diagnosis of suspected skin conditions.

About the Author: Nicholas J. Farrell, M.D.

Dr. Nicholas Farrell is a practicing oncologist at Maryland Oncology Hematology’s
Aquilino Cancer Center in Rockville and grew up in Northern Virginia and completed his undergraduate training in business at James Madison University. After working as a consultant for a few years, he made a life changing decision to attend medical school. In 2000, the graduated from the Medical College of Virginia of Virginia Commonwealth University. He completed his internal medicine residency at the University of Washington, Physical Medicine and Rehabilitation and he completed his fellowship in Hematology/ Oncology at Virginia Commonwealth University Health System. He is board certified in medical oncology.

Dr. Farrell was an assistant professor of internal medicine and primary care at Virginia Commonwealth University Health System. He is an active member in the following professional societies: American Medical Association, Montgomery County Medical, Medical & Chirurgical Faculty of the State of Maryland, American Society of Clinical Oncology and the American Society of Hematology. Outside of his oncology and hematology practice, Dr. Farrell enjoys spending time with his wife and two growing boys.

References

1. Garbe C, Leiter U. Epidemiology of melanoma and nonmelanoma skin cancer-the role of sunlight. Adv Exp Med Biol. 2008;624:89-103. doi:10.1007/978-0-387-77574-6_8

2. Patel R V., Frankel A, Goldenberg G. An update on nonmelanoma skin cancer. J Clin Aesthet Dermatol. 2011;4(2):20-27. Accessed May 4, 2021. /pmc/articles/PMC3050615/

3. Rubin AI, Chen EH, Ratner D. Basal-Cell Carcinoma. N Engl J Med. 2005;353(21):2262-2269. doi:10.1056/NEJMra044151

4. Combalia A, Carrera C. Squamous Cell Carcinoma: An Update on Diagnosis and Treatment. Dermatol Pract Concept. 2020;10(3):e2020066. doi:10.5826/dpc.1003a66

5. Siegel RL, Miller KD, Fuchs HE, Jemal A. Cancer Statistics, 2021. CA Cancer J Clin. 2021;71(1):7-33. doi:10.3322/caac.21654

6. Etzkorn JR, Parikh RP, Marzban SS, et al. Identifying risk factors using a skin cancer screening program. Cancer Control. 2013;20(4):248-254. doi:10.1177/107327481302000402

7. Tsao H, Olazagasti JM, Cordoro KM, et al. Early detection of melanoma: Reviewing the ABCDEs American Academy of Dermatology Ad Hoc Task Force for the ABCDEs of Melanoma. J Am Acad Dermatol. 2015;72(4):717-723. doi:10.1016/j.jaad.2015.01.025

8. Linos E, Katz KA, Colditz GA. Skin cancer - The importance of prevention. JAMA Intern Med. 2016;176(10):1435-1436. doi:10.1001/jamainternmed.2016.5008