AMSTERDAM — Adoption of a diet rich in leafy green vegetables and the regular use of NSAIDs are evidence-based supplementary measures available to patients with prior skin cancer to reduce their risk of future episodes, Dr. Adele C. Green said at the 11th World Congress on Cancers of the Skin.
Diet and NSAIDs join regular daily sunscreen use as three secondary prevention strategies that can be offered to patients beyond the prevention mainstay, which remains physical sun avoidance, added Dr. Green, head of the cancer and population studies group at Australia's Queensland Institute of Medical Research, Brisbane.
The supporting evidence for these three supplementary preventive measures comes from the prospective community-based Nambour (Queensland) Skin Cancer Study, in which 1,621 adults in the town of Nambour were randomized to daily use of a broad-spectrum SPF 17 sunscreen, or discretionary and less frequent use. The evidence for reduced squamous cell carcinoma (SCC) risk based upon food consumption patterns comes from the prospective observational portion of the Nambour study. Participants completed a detailed semiquantitative food frequency questionnaire addressing their consumption of 38 food groups on three occasions during follow-up. In a multivariate regression analysis adjusted for sunscreen use, skin color, and other potential confounders, a dietary pattern featuring rich consumption of meats and fats was associated with a significant 1.8-fold increased risk of developing SCC during 10 years of follow-up.
Moreover, in subjects with a baseline history of skin cancer, being in the top tertile in terms of the meat and fat dietary pattern was associated with a 3.4-fold increased risk of SCC, compared with those in the lowest tertile. Other components of the meat and fat dietary pattern commonly included beer, potatoes, eggs, and white bread.
In contrast, dietary pattern had no effect at all on the risk of developing basal cell carcinoma.
Participants in the highest tertile in terms of the vegetable and fruit dietary pattern—which also included fish, whole grain breads, legumes, and rice—had a 54% reduction in risk of developing SCC, compared with those in the lowest tertile. “Upon further analysis, this was totally explained by the consumption of green leafy vegetables, like spinach and lettuce, with no added value [found in] the other components of the diet,” according to Dr. Green.
The NSAID analysis in the Nambour study was prompted by an anecdotal observation.
“We noticed that people taking NSAIDs or aspirin for, say, arthritic conditions seemed to have smoother skin than their colleagues who were not. So we looked at this more formally in our study population,” she explained.
The NSAID analysis took the form of a nested, longitudinal, case-control study involving 86 participants with SCC and 187 randomly selected age- and gender-matched controls. It showed that individuals with SCC were less than one-tenth as likely as controls to have taken an NSAID tablet or at least 200 mg of aspirin eight or more times per week for more than 1 year. Those with SCC were also only one-fifth as likely to have used NSAIDs or aspirin two or more times per week for more than 5 years.
Among subjects without SCC, current users of NSAIDs or aspirin two or more times per week had half as many actinic keratoses compared with nonusers, Dr. Green said at the congress cosponsored by the Skin Cancer Foundation and Erasmus University.
In an interview, Dr. Alan C. Halpern pronounced the NSAID findings particularly interesting as well as biologically plausible. He noted that with all the negative headlines about the increased cardiovascular risk associated with NSAIDs, it's often forgotten that, well beforehand, multiple randomized trials were underway looking at NSAIDs for prevention of various forms of cancer.
“Some of us have seen patients in our own practices who actually seem to have had cancers go away with NSAIDs. I'm completely on the same page as Dr. Green on this,” said Dr. Halpern, chief of the dermatology service at Memorial Sloan-Kettering Cancer Center, New York, and cochairman of the National Council on Skin Cancer Prevention.
The reduction in risk was associated with eating green leafy vegetables, such as spinach and lettuce. DR. GREEN
The NSAID findings are particularly interesting as well as biologically plausible. DR. HALPERN