Martha’s Vineyard residents and visitors enjoy the outdoors, particularly in the summer months, when people flock to Island beaches and waters. However, those pleasurable hours spent in the sun carry risks that may not be readily apparent.
Skin cancer rates, in particular for melanoma, the most virulent form of skin cancer, on Martha’s Vineyard are well above state and national averages, according to the National Cancer Institute (NCI). The risk of being diagnosed with melanoma in Dukes County, which includes the Elizabeth Islands, is significantly higher than anywhere else in the state. The risk of being diagnosed is measured by the incidence rate. The rate measures the number of new cases per population at risk in a given time period.
Skin cancer is the most common cancer diagnosed in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC). Melanoma is a particularly malignant form of skin cancer that can spread to other parts of the body.
It is the fifth most common cancer for males, and seventh most common for females, according to the American Cancer Society. The risk factors include a family history of melanoma, the presence of atypical moles, sensitivity to sun exposure, and a history of sunburns.
The state average for melanoma incidence rates per 100,000 people was 21.9, from 2007 to 2011, according to a report by the CDC. According to the same profile, the melanoma incidence rate for Dukes County was 33.5 per 100,000 people.
Dukes County has the third highest melanoma incidence rate in the state, and is 70 percent above the national average. According to the state profile provided by the CDC, the communities of Dukes, Barnstable, and Nantucket County are all well above the state and national average.
Melanoma incidence is related to age, but it has an unusual pattern when compared with other cancer types. According to the American Cancer Society (ACS), “melanoma is generally more common in men than in women, but this varies by age. Before age 45, the risk is higher for women; after age 45 the risk is higher in men.”
The Census Bureau states that in Dukes County, the biggest population increase over the past 10 years took place among people who are 35 to 54 years old, with 22.1 percent of the population 55 and older.
In conversations with the Times, area dermatologists offered several explanations for the increasingly high incident rates of melanoma in Dukes County.
“The rates of melanoma have been on a steady rise over the past decade,” Dr. Mark Liska of Dermatology of Cape Cod told The Times. “Every year I send a melanoma incident report to the state, and they are always surprised by the increasingly high numbers.”
Dr. Liska said the age of the Island population could also be a factor. “The demographics of the Cape and Islands also point to the large amount of retired people,” he said. “This could also be an important factor that could lead to a high melanoma incidence rate.”
One explanation could lie with the Island’s demographics. According to the United States Census Bureau’s most recent 2013 report, 91 percent of the Dukes County population is white, compared with a state average of 83.2 percent.
“One plausible hypothesis could be an imbalance between skin pigmentation and sun exposure,” said Massachusetts General Hospital Dermatology Chief Dr. David Fisher in a recent email to The Times. “Lighter-skinned populations, when exposed to intense sunlight/ultraviolet radiation, are at higher risk for developing melanoma.”
When asked about the reasons behind the large differences in incidence rates, Dr. Fisher said, “Sun exposure behaviors may be different, aside from sunscreen use — both of which may influence the skin cancer risk in aggregate. It is possible that skin pigmentation status may also contribute to skin cancer risk in Martha’s Vineyard’s population.”
Dr. Richard Penson, a professor at the Harvard Medical School and the clinical director for cancer services at Martha’s Vineyard Hospital and Nantucket Hospital, offered a view on the high rates and melanoma trends overall.
Dr. Penson cautioned against reading too much into statistics when there is a small sampling.
“The thing about epidemiology is that you have to look at bigger areas to come up with associations; causality is really hard to demonstrate. When you look at small areas’ epidemiology, the amount of variation and multiple facets get very complicated.”
Asked about the notion that the high rates could be due to the age and race of the Island population, Dr. Penson said it is hard to say for certain what might be behind high melanoma incidence rates.
“All the hypotheses mentioned, UV exposure and age, are clearly important, but it’s hard to collect enough data to come up with a causality,” he said. “I would say that having a family history of melanoma plays a larger role than previously anticipated in the incidence and outcomes of melanoma.”
Prevention is key
“Sun protection remains the foundation of skin cancer prevention,” said Dr. Fisher. There are many steps people can take to reduce the risk of getting melanoma.
According to the ACS, there are several ways people can reduce the risk of getting melanoma: Limit your sun exposure, use sunscreen, stay in the shade, avoid tanning beds, protect children from the sun, and watch for abnormal moles.
“The most important prevention opportunity is to educate people about the risks of melanoma and sun exposure,” said Dr. Fisher.
For more information about melanoma, visit: cancer.org/%20cancer/skincancer-melanoma/index.