Study Examines Role of Diet in Melanoma Prognosis

Research does not establish causality, but reveals significant relationships between food choices and melanoma thickness.

Eating a low-quality diet raises risks of a host of well-known health issues. A study published in the Journal of the European Academy of Dermatology and Venereology adds thicker melanomas to the list of potential perils linked with poor diet.1

Diet is a discretionary modulating factor that dermatologists and other clinicians can tell their patients about to reduce patients’ risk of dying from melanoma, said corresponding author Adele Green, MD. She is a senior scientist in the Department of Population Health at QIMR Berghofer Medical Research Institute in Brisbane, Australia, and honorary professor of epidemiology at the University of Manchester, in Manchester, UK.

“We know what causes melanoma—mostly ultraviolet light from the sun,” she told Dermatology Times®. “We don’t really know what background factors might improve patients’ prognosis when they get melanoma.”

In other major cancers such as breast cancer and prostate cancer, solid evidence shows that diet significantly influences outcomes.2,3 “When you develop melanoma,” she said, “we would like to know, because it’s such a terrible disease in advanced stages, how patients might be able to best influence their outcomes. And diet is an obvious factor that people can control.”

The study population included 634 patients with incident stage Ib through IV cutaneous melanoma diagnosed between 2010 and 2014. In total, 38% of patients had thick (>2 mm) melanomas at diagnosis. These patients were significantly older (64 versus 61 years) and more likely to be male (67%, P = 0.0009) than patients with thinner melanomas.

Additionally, patients completed a validated 142-item semi-quantitative food frequency questionnaire.4 Using questionnaire data, investigators calculated patients’ Healthy Eating Index (HEI) scores, which measure how closely eating and drinking habits adhere to regularly updated American dietary guidelines.5

After dividing HEI scores into tertiles and adjusting for known confounders such as age, sex, and socioeconomic factors, investigators found that patients with the highest HEI scores were significantly less likely to be diagnosed with thick melanomas than were patients with the lowest HEI scores (adjusted prevalence ratio 0.93; 95% CI 0.86-0.99; P = 0.03). “Notably,” authors wrote, “we adjusted for frequency of skin checks (both by doctor and self) because frequent skin checks are associated with thinner melanomas, as well as higher education and other positive health-related behaviors like not smoking and sun protection/avoidance, all of which are associated with eating habits.”

Most clinicians are unlikely to discuss diet with patients, said Green, beyond well-known associations with entities such as cardiovascular disease and cancers generally. “People are well aware that in general, a better-quality diet is going to stand them in good stead.”

But rather than broadly recommending a healthy diet to patients, she said, focusing on specific foods and food groups may be more helpful and yield better results. “We found particular aspects that could be improved upon, even in people with thin melanomas.” Specifically, all study patients had low compliance (below 50%) for mono- and polyunsaturated fats (found in fish, beans, legumes, nuts, and seeds). “Also, those with thick melanomas were not eating the recommended levels of fruits or whole grains,” she added.

Study findings broadly support the only previous study that assessed diet and melanoma prognosis. It showed better survival in patients who ate fruit daily, and worse survival in those who ate red meat daily.6 “We’ve gone much further than before with our dietary analysis, as we examined patients’ overall diets as well as individual dietary components.”

Researchers would have preferred to link eating habits with melanoma mortality, Green said. But today’s generally low melanoma mortality rates required them to substitute thickness, which she said is an excellent surrogate for melanoma mortality, and that boosted statistical power. Study weaknesses included its reliance on patient self-reporting of dietary data. Despite uncovering significant relationships unlikely to result from chance, Green added, the study does not establish causality, and confirmatory prospective evidence is needed.

Disclosures:

Green reports no relevant financial interests.

References:

1. Hughes MCB, Malt M, Khosrotehrani K, Smithers BM, Green AC. Diet quality is associated with primary melanoma thickness [published online ahead of print, 2022 Apr 24]. J Eur Acad Dermatol Venereol. 2022;10.1111/jdv.18174. doi:10.1111/jdv.18174

2. Davies NJ, Batehup L, Thomas R. The role of diet and physical activity in breast, colorectal, and prostate cancer survivorship: a review of the literature. Br J Cancer. 2011;105 Suppl 1(Suppl 1):S52-S73. doi:10.1038/bjc.2011.423

3. Kord-Varkaneh H, Salehi-Sahlabadi A, Zarezade M, et al. Association between Healthy Eating Index-2015 and breast cancer risk: a case-control study. Asian Pac J Cancer Prev. 2020;21(5):1363-1367. Published 2020 May 1. doi:10.31557/APJCP.2020.21.5.1363

4. Willett WC, Sampson L, Stampfer MJ, et al. Reproducibility and validity of a semiquantitative food frequency questionnaire. Am J Epidemiol. 1985;122(1):51-65. doi:10.1093/oxfordjournals.aje.a114086

5. Krebs-Smith SM, Pannucci TE, Subar AF, et al. Update of the Healthy Eating Index: HEI-2015 [published correction appears in J Acad Nutr Diet. 2019 Aug 20;:]. J Acad Nutr Diet. 2018;118(9):1591-1602. doi:10.1016/j.jand.2018.05.021

6. Gould Rothberg BE, Bulloch KJ, Fine JA, Barnhill RL, Berwick M. Red meat and fruit intake is prognostic among patients with localized cutaneous melanomas more than 1mm thick. Cancer Epidemiol. 2014;38(5):599-607. doi:10.1016/j.canep.2014.08.005