The incidence of melanoma has continued to increase in the United States and worldwide during the last four decades. Yearly estimates showed that 47,700 people in the U.S. were expected to be diagnosed with melanoma in 2000, but that number rose to 68,720 by 2009.1, 2
Recent studies have questioned whether there truly is a melanoma epidemic or if rising rates reflect a change in how doctors diagnose melanoma and the availability of skin cancer screenings. Dermatologist Darrell S. Rigel, MD, FAAD, clinical professor of dermatology at New York University Medical Center in New York, explains why he believes there is a legitimate increase in the number of people diagnosed with melanoma and why he believes that number may increase in the future.
Are melanoma rates increasing?
Myth: Rise in melanoma incidence is due to increased surveillance. Some studies have attributed a rise in melanoma incidence to an increase in the number of skin cancer screenings. If this theory was true, Dr. Rigel believes there would have been a decline in the number of melanoma cases in recent years. Theoretically, those cases would have already been detected once skin cancer screenings became more readily accessible in the 1980s similar to what happened to prostate cancer rates. Dr. Rigel noted that prostate cancer incidence rapidly increased from 1988-1992, declined sharply from 1992-1995, and leveled off since 1995.2 Dr. Rigel attributes these changes to the increase in the number of men whose PSA levels were tested. Once those initial cases of prostate cancer were diagnosed, prostate cancer was not diagnosed as often. Such a trend is not occurring with melanoma rates.
Myth: Rise in melanoma incidence is due to a change in how pathologists diagnose melanoma.
Dr. Rigel pointed to a multicenter study that reviewed the diagnoses of 2,600 pigmented lesions taken from the 1930s to the 1970s.3 The lesions were re-analyzed in 1990 and there was no significant change in the result of the diagnosis. Therefore, Dr. Rigel does not believe the increase in melanoma incidence is due to a change in how pathologists diagnose melanoma. In addition, increasing incidence of thicker melanomas has been reported in population-based studies, and an increase among more fatal, thick (>4mm) tumors was found in a recent analysis using data from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) program, which suggests a legitimate increase in melanoma rates.4
Myth: Rise in melanoma incidence is due to better ways of counting cancer.
Dr. Rigel pointed out that incidence rates are based on reports from hospitals. Because melanoma is the only major cancer more often diagnosed in an outpatient setting, he believes melanoma incidence may be underreported, especially with the trend of shifting to outpatient health care. Therefore, he does not believe the rise in incidence is due to any changes in the ways cancer cases are counted.
Dr. Rigel notes that because more people are dying of melanoma and more people are surviving melanoma then the only mathematical option is that the incidence is rising as well.
Why are melanoma rates increasing?
Some people are not protecting themselves from sun exposure while others subject themselves to ultraviolet (UV) radiation from indoor tanning beds and lamps. In fact, nearly 28 million people tan indoors in the United States annually.5,6 Nearly 70 percent of tanning salon patrons are Caucasian girls and women, primarily aged 16 to 29 years, which Dr. Rigel says may explain why the torso is the most common location for developing melanoma in females 15-29 years old.7,8 Depletion of the ozone layer may contribute to the increase in melanoma incidence because it allows more UV radiation to reach the earth's surface.
Will melanoma rates continue to rise?
Dr. Rigel says melanoma rates will continue to rise as long as people continue to receive excessive UV exposure from the sun and tanning beds. However, he believes that without efforts to educate people about the importance of sun protection, the increase would be much worse.
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American Cancer Society. 2000 Cancer Facts and Figures
American Cancer Society. 2009 Cancer Facts and Figures
Van der Esch EP, Muir CS, Nectoux J, Macfarlane G, Maisonneuve P, Bharucha H, Briggs J, Cooke RA, Dempster AG, Essex WB, et al. Temporal change in diagnostic criteria as a cause of the increase of malignant melanoma over time is unlikely. Int J Cancer. 1991 Feb 20;47(4):483-9.
Linos E, Swetter SM, Cockburn MG, Colditz GA, Clarke CA. Increasing burden of melanoma in the United States. J Invest Dermatol. 2009 Jul;129(7):1666-74. Epub 2009 Jan 8.
Kwon HT, Mayer JA, Walker KK, Yu H, Lewis EC, Belch GE. Promotion of frequent tanning sessions by indoor tanning facilities: two studies. J Am Acad Dermatol 2002;46:700-5.
Dellavalle RP, Parker ER, Ceronsky N, Hester EJ, Hemme B, Burkhardt DL, et al. Youth access laws: in the dark at the tanning parlor? Arch Dermatol 2003;139:443-8.
Swerdlow AJ, Weinstock MA. Do tanning lamps cause melanoma? An epidemiologic assessment. J Am Acad Dermatol 1998;38:89-98.
World Health Organization, Solar ultraviolet radiation: Global burden of disease from solar ultraviolet radiation. Environmental Burden of Disease Series, N.13. 2006.