Melanoma Rates Rising Among Latinos

California is experiencing a “developing epidemic” of melanoma among Latinos, according to a study by USC researchers released Monday.

Although the incidence is still much lower among Latinos than among whites, the researchers are alarmed because the greatest increase is in the rate of so-called thick tumors, which are much more likely to be lethal, according to a report in the journal Cancer.

The number of total melanoma cases among Latinos is small -- about 200 new cases per year and about 50 deaths, said epidemiologist Myles G. Cockburn of USC’s Keck School of Medicine.

But the rate of the skin cancer among Latino males has been growing by nearly 7% per year for the past five years, about double the rate for whites, according to the study.

Latinos have been thought to be largely immune to melanoma because their skin pigments provide protection from the sun’s damaging ultraviolet rays.

Even many doctors have accepted this theory and are not aggressive in checking for melanomas in Latino patients or in following up on them when they are detected, Cockburn said.

Physicians must be more aggressive in targeting prevention programs to Latinos, who account for about a third of the state’s population, Cockburn said.

“There is no reason for anyone to die from this,” he added.

The USC study focused on California because of its 12 million Latino residents and accurate cancer registries. Cockburn said the results should hold for the rest of the country.

Melanoma incidence has been growing among all groups over the past 20 years, in large part because of increased exposure to the sun through outdoor recreation. The increase in incidence is second only to that of prostate cancer, Cockburn said.

There has been little accurate information about incidence among Latinos and other minority groups. There is, for example, no incidence data from Mexico because of poor information gathering. In other areas, the Latino population is too small for accurate tracking.

Cockburn and his colleagues studied all melanoma cases among Latino-surnamed Californians from 1988 through 2001. At the beginning of the study, the cancer had an incidence of 2.8 cases per 100,000 Latino males, compared with a rate of 17.2 cases per 100,000 white males.

The disease accounted for 1.2% of all male cancers and 1.6% of female cancers among Latinos, comparable to esophageal cancer and Hodgkin’s disease.

The study found that melanoma among Latinos grew on average 1.8% per year over the entire 14 years of the study, but nearly 7% per year for the past five years. Among whites during the same 14-year period, the incidence grew by 3.9% per year for men and 3.3% per year for females.

Physicians generally differentiate melanomas into two groups: those less than 0.75 millimeters thick (about the thickness of a credit card) and those more than 1.5 millimeters thick.

For the first group, the survival rate 10 years after diagnosis is between 80% and 100%, according to Dr. Anthony Lopez of UC San Diego. For the thicker tumors, which are more likely to have spread to other sites in the body, the survival rate is between 40% and 80%.

The incidence of thick tumors has been growing at about 15% per year among Latino males, accounting for most of the increase in the melanoma rate, Cockburn said.

By the end of the study, they accounted for 24.4% of tumors among white males, but 35.4% among Latino males.

“When a tumor is thick, that usually means it has been developing for a while,” Cockburn said. “This is a disease that has a great chance of cure when found early.... But in this population, the cancer is becoming more common and it is not being caught early enough.”