Home > Medical Reference > Patient Education

Ask the Expert

Get answers to your Melanoma questions.

Note: This is for informational purposes only. Doctors cannot provide a diagnosis or individual treatment advice via e-mail. Please consult your physician about your specific health care concerns.

Please install flash player to see this video.

Cancer Center Virtual Tour

Melanoma and other skin cancers - Causes

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of melanoma and nonmelanoma skin cancers.

Alternative Names

Skin cancer; Squamous cell cancer; Basal cell cancer; Actinic keratosis; Nonmelanoma skin cancer

Causes:

The sun is the most important cause of prematurely aging skin (called photoaging) and skin cancers.

Long-term, repeated exposure to sunlight appears to be responsible for most undesirable consequences of aging skin, including basal cell and squamous cell cancers.

Melanoma is more likely to be caused by intense exposure to sunlight in early life.

UVA and UVB Radiation. When sunlight penetrates the top layers of the skin, ultraviolet (UVA or UVB) radiation strikes the DNA inside the skin cells and damages it.

UVB is the main type of radiation responsible for sunburns. It primarily affects the outer skin layers. This type of ultraviolet light is most intense at midday when sunlight is brightest.
UVA penetrates more deeply and efficiently. Unlike with UVB, window glass does not filter out UVA rays.

Damaging Effects of UV Radiation. Both UVA and UVB rays cause damage, including genetic injury, wrinkles, lower immunity against infection, aging skin disorders, and cancer, although the mechanisms are not yet fully clear. The following are some ways in which cancer may develop, and some actions the skin uses to defend itself against DNA damage.

Oxidation and Antioxidants. The effects of UV radiation are implicated in the production of oxidants, also called free radicals. Free radicals are unstable molecules produced by normal chemical processes in the body that, in excess, can damage the body's cells and even alter the DNA. This contributes to the aging process and sometimes to cancer.
Defective DNA Repair and Protective Enzymes. Some skin cancers are caused by a breakdown in the body's mechanisms that help repair DNA damage. For example, xeroderma pigmentosum (XP) is a rare genetic disease in which the body cannot repair damage caused by ultraviolet light. Normally, a number of enzymes in the skin help protect against this damage.
Breakdown of Immune Protection. Specific immune factors protect the skin, including white blood cells called T lymphocytes and specialized skin cells called Langerhans cells. These immune system cells attack developing cancer cells at the very earliest stages. However, certain substances in the skin, particularly a chemical called urocanic acid, can suppress such immune factors when exposed to sunlight.

Defective Cell Death (Apoptosis). Apoptosis is the last defense of the immune system. It is a natural process of cell-suicide, which occurs when cells are very severely damaged. Apoptosis in the skin kills off cells harmed by UVA so that they do not turn cancerous. The peeling after sunburn is the result of these dead skin cells. However, some gene defects or other factors can interfere with apoptosis. If this occurs, damaged cells can continue to spread, resulting in skin cancer.

Resources

www.aad.org -- American Academy of Dermatology
www.cancer.org -- American Cancer Society
www.asds.net -- American Society for Dermatologic Surgery
www.mpip.org -- Melanoma Patients' Information Page
www.cancer.gov -- National Cancer Institute
www.nccn.org -- National Comprehensive Cancer Network
www.skincancer.org -- The Skin Cancer Foundation
www.epa.gov/sunwise/uvindex.html -- UV index information

References

Abbasi NR, Yancovitz M, Gutkowicz-Krusin D, Panageas K, Googe P, King R, et al. Utility of lesion diameter in the clinical diagnosis of cutaneous melanoma. Arch Dermatol. 2008;144:469-474.

American Cancer Society. Cancer Facts and Figures 2008. Atlanta, GA: American Cancer Society; 2008.

Anderson L, Schmieder GJ, Werschler WP, et al. Randomized, double-blind, double-dummy, vehicle-controlled study of ingenol mebutate gel 0.025% and 0.05% for actinic keratosis. J Am Acad Dermatol. 2009;60(6):934-43.

Basal cell and squamous cell cancers: NCCN Medical Practice Guidelines and Oncology;V.1.2009. Accessed July 15, 2009.

Braathen LR, Szeimies RM, Basset-Seguin N, Bissonnette R, Foley P, Pariser D, et al. Guidelines on the use of photodynamic therapy for nonmelanoma skin cancer: an international consensus. International Society for Photodynamic Therapy In Dermatology, 2005. J Am Acad Dermatol. 2005;56:125-143.

Brantsch KD, Meisner C, Schonfisch B, Trilling B, Wehner-Caroli J, Rocken M, et al. Analysis of risk factors determining prognosis of cutaneous squamous-cell carcinoma: a prospective study. The Lancet Oncology. 2008;9:713-720.

Clinical practice guideline for melanoma: NCCN Medical Practice Guidelines and Oncology;V.2.2009. Accessed July 15, 2009.

Cyr PR. Atypical Moles. Am Fam Physician. 2008;78(6):735-40. Review.

deBerker D, McGregor JM, Hughes BR. Guidelines for the management of actinic keratoses. Br J Dermatol. 2007;156:222-230.

Eggermont AM, Suciu S, Santinami M, et al: EORTC Melanoma Group. Adjuvant therapy with pegylated interferon alfa-2b versus observation alone in resected stage III melanoma: final result of EORTC 18991, a randomised phase III trial. Lancet. 2008;372(9633):117-26.

Garcia C, Polette E, Crowson AN. Basosquamous carcinoma. J Am Dermatol. 2009;60(1):137-43.

Goodson AG, Grossman D. Strategies for early melanoma detection: Approaches to the patient with nevi. J Am Acad Dermatol. 2009;60(5):719-35: quiz 736-8. Review.

Guadagnolo BA, Zagars GK. Adjuvant radiation therapy for high-risk notal metastases from cutaneous melanoma. Lancet Oncol. 2009;10(4):409-16.

Hexsel, CL, Bangert SD, Hebert AA, et al. Current sunscreen issues: 2007 Food and Drug Administration sunscreen labelling recommendations and combination sunscreen/insect repellent products. J Am Dermatol. 2008;59(2):316-23. Review.

Lachiewicz AM, Berwick M, Wiggins CL, Thomas NE. Survival differences between patients with scalp or neck melanoma and those with melanoma of other sites in the surveillance, epidemiology, and end results (SEER) program. Arch Dermatol. 2008;144:515-521.

Lange JR, Fecher LA, Sharfman WH, et al. Melanoma. In: Abeloff MD, Armitage JO, Nierderhuber JE, Kastan MB, McKenna WG, eds. Abeloff's Clinical Oncology. 4th ed. Philadelphia, Pa: Churchill Livingstone; 2008:chap 73.

Lautenschlager S, Wulf HC, Pittelkow MR. Photoprotection. The Lancet [early online publication]. May 3, 2007.

Markovick SN, Erickson LA, Rao RD, Weenig RH, Pockaj BA, Bardia A, et al. Malignant melanoma in the 21st century, part 1:epidemiology, risk factors, screening, prevention, and diagnosis. Mayo Clin Proc. 2007;82:364-380.

Markovick SN, Erickson LA, Rao RD, Weenig RH, Pockaj BA, Bardia A, et al. Malignant melanoma in the 21st century, part 2: staging, prognosis, and treatment. Mayo Clin Proc. 2007;82:490-513.

Morton CA, mckenna KE, Rhodes LE:British Association of Dermatologists Therapy Guidelines and Audit Subcomittee and the British Photodermatology group. Guidelines for topical photodynamic therapy: update. Br J Dermatol. 2008;159(6):1245-66. Review.

Morton DL, Thompson JF, Cochran AJ Mozzillo N, Elashoff R, Essner R, et al. Sentinel-node biopsy or nodal observation in melanoma. N Engl J Med. 2006;355:1307-1317.

Olsen CM, Zens MS, Stukel TA, et al. Nevus density and melanoma risk in women: to test the divergent pathway hypothesis. Int J Cancer. 2009;124(4):937-44.

Ridky TW. Nonmelanoma skin cancer. J Am Acad Dermatol. 2007;57:484-501.

Savel MS, Wong SI. Review of evidence-based support for pretreatment imaging in melanoma. J Natl compr Canc netw. 2009;7(3):281-9. Review.

Suh KY, Bolognia JL. Signature nevi. J Am Acad Dermatol. 2009;60(3):508-14. Review.

Telfer NR, Colver GB, Morton CA. Guidelines for the Management of Basal Cell Carcinoma. BJD. 2008;159:35-48.

Tran KT, Wright NA, Cockerell CJ. Biopsy of the pigmented lesion-when and how. J Am Acad Dermatol. 2008;59(5):852-71. Review.

Treatment for Metastatic Ocular Melanoma. NCI Cancer Bulletin. March 7, 2006;3(10):8.

Vestergaard ME, Macaskill P, Holt PE, et al. Dermoscopy compared with naket eye examination for the diagnosis of primary melanoma: a meta-analysis of studies performed in a clinical setting. Br J Dermatol. 2008;159(3):669-76.

Warycha MA, Zakrzewski J, Ni Q, et al. Meta-analysis of sentinal lymph node positivity in thin melanoma. Cancer. 2009;115(4):869-79.

Wood GS, Gunkel J, Stewart D, et al. Nonmelanoma skin cancers: basal and squamous cell carcinomas. In: Abeloff MD, Armitage JO, Nierderhuber JE, Kastan MB, McKenna WG, eds. Abeloff's Clinical Oncology. 4th ed. Philadelphia, Pa: Churchill Livingstone; 2008:chap 74.

Zeichner JA, Stern DW, Uliasz A, et al. Placebo-controlled double-blind randomized pilot study of imiquimod 5% cream applied once per week for 6 months for the treatment of actinic keratoses. J Am Acad Dermatol. 2009;60(1):59-62.

Reviewed last on: 7/30/2009
Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.