Study examines incidence of melanoma rates among California Hispanics over time

Jan 23 2006

For the first time, scientists have identified a significant increase in the incidence rate of melanoma--an invasive form of an already deadly skin cancer--among California Hispanics.

A new study published in the March 1, 2006 issue of CANCER, a peer-reviewed journal of the American Cancer Society, finds in contrast to non-Hispanic Caucasians, increases in melanoma in Hispanics have been confined to thicker lesions, which have a poorer prognosis.

While melanoma accounts for a minority of skin cancers, it is responsible for the great majority of skin cancer deaths. As a general rule, the deeper the cancer has penetrated into the layers of the skin, the higher the risk of death. The major risk factors for melanoma are fair skin and a history of significant sun exposure. California and Central America are regions of intense sun exposure. While fair skinned, non-Hispanic whites have long been considered the racial group at highest risk, little is known about the incidence of melanoma among Hispanics, the fastest-growing racial/ethnic group in the State, which has among the highest rates of melanoma in the world.

In the first study to examine the incidence of melanoma rates among California Hispanics over time, Myles G. Cockburn, Ph.D. of the Keck School of Medicine of the University of Southern California and colleagues compared melanoma trends and melanoma-related mortality data between Hispanics and non-Hispanic whites in California.

The authors report that between 1988 and 2001 the rate of invasive melanoma has increased significantly among Hispanic men compared to Hispanic women and non-Hispanic whites. The incidence rate among Hispanic males increased an average 1.8 percent per year with a staggering 7.3 percent per year increase between 1996 and 2001.

Over 55 percent of the invasive tumors in Hispanic males were greater than 0.75mm thick compared to 47 percent in non-Hispanic white males. Furthermore, a larger proportion of invasive tumors were greater than 1.5mm thick among Hispanic males (35 percent) compared to non-Hispanic white males (24 percent). Overall, the increase in thick (>1.5mm) tumors was far greater than the increase in thin (<0.75mm) or moderate (0.75mm to 1.49mm) tumors in both Hispanic males and females, increasing annually 15 percent and 9 percent, respectively.

These trends towards increasing rates of invasive and thicker melanomas in Hispanics are a cause for considerable concern for public health officials, "because primary and secondary melanoma prevention efforts are focused on white (i.e., non-Hispanic) populations."