1. ¹Northern California Cancer Center, Fremont, California, USA
2. ²Department of Dermatology, Pigmented Lesion and Melanoma Program, Stanford University Medical Center, Stanford, California, USA
3. ³Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
4. ⁴Stanford Comprehensive Cancer Center, Stanford, California, USA
5. ⁵Department of Preventive Medicine, University of Southern Calfornia/Keck School of Medicine, Los Angeles, California, USA
6. ⁶Washington University School of Medicine, Siteman Cancer Center, St Louis, Missouri, USA

Correspondence: Dr Eleni Linos, Department of Dermatology, Stanford University Medical Center, 900 Blake Wilbur Drive, W0069 Stanford, California 94305, USA. E-mail: linos@stanford.edu

Received 27 August 2008; Revised 30 October 2008; Accepted 23 November 2008; Published online 8 January 2009.

Abstract

It is controversial whether worldwide increases in melanoma incidence represent a true epidemic. Dramatic increases in incidence in the setting of relatively stable mortality trends have also been attributed to expanded skin screening and detection of biologically indolent tumors with low metastatic potential. To better understand how melanoma incidence trends varied by severity at diagnosis and factors relevant to screening access, we assessed recent United States incidence and mortality trends by histologic type, tumor thickness, and area-level socioeconomic status (SES). We obtained population-based data regarding diagnoses of invasive melanoma among non-Hispanic whites from nearly 291 million person-years of observation by the Surveillance Epidemiology and End Results (SEER) program (1992–2004). Age-adjusted incidence and mortality rates were calculated for SEER and a subset (California) for which small-area SES measure was available. Overall, melanoma incidence increased at 3.1% (P<0.001) per year. Statistically significant rises occurred for tumors of all histologic subtypes and thicknesses, including those >4 mm. Melanoma incidence rates doubled in all SES groups over a 10-year period whereas melanoma mortality rates did not increase significantly. We conclude that screening-associated diagnosis of thinner melanomas cannot explain the increasing rates of thicker melanomas among low SES populations with poorer access to screening.