Vitamin D, skin cancer screening, and chemoprevention top the list of current melanoma prevention controversies, according to Dr. Clara Curiel-Lewandowski.
Vitamin D has been a contentious subject for many years with its being suggested that increased sun protection may be associated with lower vitamin D levels, noted Dr. Lewandowski at the annual Hawaii dermatology seminar sponsored by Skin Disease Education Foundation in Maui.
"A decrease in the serum level of vitamin D has been observed in the general population, particularly here in the United States.
"The challenge is to understand to which degree each modulating factorsuch as vitamin D dietary intake, photoprotection, body mass index, and geographical locationcontributes to the observed decline in serum levels," she said in an interview.
"There is no randomized prospective study linking vitamin D deficiency to excessive photoprotection. Those studies are very difficult to carry out," said Dr. Curiel-Lewandowski, who is director of the pigmented lesion clinic and multidisciplinary oncology at the Arizona Cancer Center in Tucson.
Another component in declining vitamin D levels is that humans produce less vitamin D as they age. Therefore, rising life expectancy may have a role in decreased vitamin D levels. "We're now living to 60, 70, 80 years and we are converting less vitamin D, irrespective of other sources," she said.
In addition, normal levels of serum 25(OH)D are now in the 70-nmol/L range, where it used to be 3540 nmol/L, she said. With all of these variables, it is very difficult to tease out which of the components are responsible for declining vitamin D levels.
Advice to skin cancer patients about vitamin D should be based on common sense, said Dr. Curiel-Lewandowski.
She recommends that patients pursue a balanced diet, take daily vitamin D supplements above 400 IU if needed, and limit sun exposure to early morning and late afternoon hours. The specific dose supplementation for individuals with suspected risk factors for vitamin D deficiency should be based on their serum 25(OH)D levels.
Skin Cancer Screening
It's important to make the distinction between screening the general population and screening specific high-risk groups for skin cancer, said Dr. Curiel-Lewandowski.
"Cost effectiveness of massive skin cancer screening in the general population has been questioned," she said. An agreement needs to be reached on who is at risk for melanoma and how to target them for skin cancer screening.
The United States Preventive Services Task Force just released new recommendations on skin cancer screening for the general population (Ann. Intern. Med. 2009;150:18893).
The task force said that there is insufficient evidence to recommend for or against skin cancer screening in the general population. (See story on pg. 4.)
"It is important to understandno one is against skin cancer screening," said Dr. Curiel-Lewandowski. There simply are not enough data to recommend for or against it in the general population.
"In order to properly validate the effectiveness of massive or selective screening, randomized prospective studies will need to be completed. However, the incidence of melanoma is lower compared with other cancers and in order to get significance, you need more than 400,000 subjects involved and followed for over 10 years to achieve reasonable outcome data. … It's a very difficult study to accomplish," she said.
The task force did identify high-risk groups of individuals: fair-skinned men and women older than 65 years, patients with atypical nevi, patients with more than 50 nevi, and those with a family history of melanoma.
"What's not clear from this message is what to do with people that are known to be at high risk," she said, noting that the new recommendations identify these groups "but they don't tell you the type of screening and frequency that is recommended."
These are precisely the patients that many dermatologists seepatients with atypical nevi, those with a family history of melanoma, and transplant patients. Screenings should be done for these individuals, said Dr. Curiel-Lewandowski.
Chemoprevention
"The reason why the concept of melanoma chemoprevention is emerging is because new alternatives are necessary to decrease the burden of disease, especially in high risk individuals. This rationale is particularly compelling since we haven't been successful in decreasing mortality rates. … It opens up another option, which is trying to identify systemic agents that can be used in individuals at higher risk for melanoma to slow down the development of disease or even prevent it," Dr. Curiel-Lewandowski commented.
In the 1980s, studies were performed using topical retinoids for atypical nevi. In the late 1990s, statins became the hot topic. Neither option panned out. "What is emerging now among several candidate agents are nonsteroidal anti-inflammatories and green tea derivatives" she said.