Citrus Consumption and Risk of Cutaneous Malignant Melanoma in the Women's Health Initiative

Associations of Dietary Factors with Cutaneous Melanoma: A Case-Control Study in Greece with Literature Review

INTRODUCTION

It has been postulated that nutrition may influence the risk for cutaneous melanoma (CM); therefore, we aimed to assess the associations of food groups and individual nutrient intakes with CM in a Greek population.

METHODS

In this case-control study, 151 patients with histologically confirmed CM, newly diagnosed and treated in the Oncology Department of the "Laikon" University Hospital (Athens, Greece), and 151 age- and sex-matched healthy individuals residing in the Athens metropolitan area, recruited among participants for routine health examinations, were included. All participants completed a questionnaire comprising anthropometric measurements, sociodemographic, lifestyle, and health-related variables. A validated, semiquantitative food frequency questionnaire was used to assess average consumption of 136 food items during the 12 months preceding the onset of disease. Multivariate conditional regression models were used to derive odds ratios (ORs) with 95% confidence intervals (95% CI) regarding the association of nine food groups and seven macronutrients with CM.

RESULTS

Statistically significant positive associations with CM were found with higher energy intake (OR: 1.67, 95% CI: 1.22-2.30) and intake of saturated fatty acids (OR: 2.28, 95% CI: 1.00-5.28), after adjusting for sun sensitivity, major depression history, and alcohol intake. Inverse associations with higher intake of milk and dairy products (OR: 0.65, 95% CI: 0.48-0.88), fruits (OR: 0.68, 95% CI: 0.51-0.90), added lipids (OR: 0.65, 95% CI: 0.47-0.91), and sugars and syrups (OR: 0.70, 95% CI: 0.53-0.93) were also observed.

CONCLUSIONS

Beyond intrinsic risk factors, our results support associations of CM with multiple food groups and nutrients; if confirmed by prospective studies, these findings can add further knowledge about this fatal cancer.

Letter to the editor - dietary adjustment may be more than skin deep

PURPOSE

To evaluate the sufficiency of the dietary adjustment of dietary risk factors, made in the recent study by Li et al. published in Cancer Causes & Controls. The main research question is: are the dietary adjustments in Li et al. sufficient enough to control for specific dietary food groups?

METHODS

An evaluation of three methodological problems in Li et al.was performed; (1) the adjustment of total fruit intake, and how it relates to citrus fruit intake; (2) the adjustment of meat intake, and its relation to red and processed meat intake; (3) broad categorization of fish intake, and how it may limit interpretation.

RESULTS

Adjusting for both total fruit intake and meat intake may not be enough to control the effect of specific dietary components which may affect melanoma risk, such as citrus fruit, and red and processed meat intake, causing an increased risk of residual confounding. Moreover, with no distinguishment between fresh and canned tuna in the dietary survey, significant limitations may be present.

CONCLUSION

The dietary adjustments conducted in the study by Li et al. may not capture the intake of citrus fruit or red and processed meat, relevant to the risk of melanoma, and may induce residual confounding.

Citrus Consumption and Risk of Melanoma: A Dose-Response Meta-Analysis of Prospective Cohort Studies

Background

Epidemiological studies of citrus consumption in relation to melanoma risk have yielded conflicting results. This meta-analysis was performed to investigate the dose-response association between citrus consumption and risk of melanoma.

Methods

Relevant prospective cohort studies were identified by searching PubMed, Embase, Scopus, and Web of Science databases up to February 28th, 2022. Results from individual studies were pooled using a random-effects model.

Results

Five prospective studies, with 8,836 melanoma cases and 977,558 participants, were included in the meta-analysis. A significantly increased risk of melanoma was associated with the highest categories of either total citrus products (RR: 1.20; 95% CI: 1.01–1.42) or citrus fruit consumption (1.15; 1.04–1.28), but consumption of citrus juice was not associated with melanoma risk (1.08; 0.97–1.21). The dose-response analyses revealed that for per 1 serving/day increase in total citrus or citrus fruit consumption, the risk of melanoma increased by 9 and 12%, respectively. An inverted U-shaped curvilinear relationship, but not linear association, was observed between citrus juice consumption and melanoma risk.

Conclusions

Citrus consumption was generally associated with a greater risk of malignant melanoma. Our findings may have important public health implications with respect to preventing melanoma.

The cure from within? a review of the microbiome and diet in melanoma

Therapy for cutaneous melanoma, the deadliest of the skin cancers, is inextricably linked to the immune system. Once thought impossible, cures for metastatic melanoma with immune checkpoint inhibitors have been developed within the last decade and now occur regularly in the clinic. Unfortunately, half of tumors do not respond to checkpoint inhibitors and efforts to further exploit the immune system are needed. Tantalizing associations with immune health and gut microbiome composition suggest we can improve the success rate of immunotherapy. The gut contains over half of the immune cells in our bodies and increasingly, evidence is linking the immune system within our gut to melanoma development and treatment. In this review, we discuss the importance the skin and gut microbiome may play in the development of melanoma. We examine the differences in the microbial populations which inhabit the gut of those who develop melanoma and subsequently respond to immunotherapeutics. We discuss the role of dietary intake on the development and treatment of melanoma. And finally, we review the landscape of published and registered clinical trials therapeutically targeting the microbiome in melanoma through dietary supplements, fecal microbiota transplant, and microbial supplementation.

Citrus-Gene interaction and melanoma risk in the UK Biobank

High citrus consumption may increase melanoma risk; however, little is known about the biological mechanisms of this association, or whether it is modified by genetic variants. We conducted a genome-wide analysis of gene-citrus consumption interactions on melanoma risk among 1563 melanoma cases and 193 296 controls from the UK Biobank. Both the 2-degrees-of-freedom (df) joint test of genetic main effect and gene-environment (G-E) interaction and the standard 1-df G-E interaction test were performed. Three index SNPs (lowest P-value SNP among highly correlated variants [r²  > .6]) were identified from among the 365 genome-wide significant 2-df test results (rs183783391 on chromosome 3 [MITF], rs869329 on chromosome 9 [MTAP] and rs11446223 on chromosome 16 [DEF8]). Although all three were statistically significant for the 2-df test (4.25e-08, 1.98e-10 and 4.93e-13, respectively), none showed evidence of interaction according to the 1-df test (P = .73, .24 and .12, respectively). Eight nonindex, 2-df test significant SNPs on chromosome 16 were significant (P < .05) according to the 1-df test, providing evidence of citrus-gene interaction. Seven of these SNPs were mapped to AFG3L1P (rs199600347, rs111822773, rs113178244, rs3803683, rs73283867, rs78800020, rs73283871), and one SNP was mapped to GAS8 (rs74583214). We identified several genetic loci that may elucidate the association between citrus consumption and melanoma risk. Further studies are needed to confirm these findings.

The association between citrus consumption and melanoma risk in the UK Biobank

BACKGROUND

Melanoma incidence has been dramatically increasing worldwide. Psoralen, a known photocarcinogen, is naturally abundant in citrus products, leading to the hypothesis that high citrus consumption may increase melanoma risk.

OBJECTIVES

To investigate the association between total citrus consumption and melanoma risk, and the association between individual citrus products and melanoma risk, and to test for interactions between total citrus intake and established melanoma risk factors.

METHODS

Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between citrus consumption and melanoma risk among 1592 cases and 197 372 controls from the UK Biobank cohort. Citrus consumption data were collected via five rounds of 24-h recall questionnaires. International Classification of Diseases codes were used to determine melanoma outcome.

RESULTS

After adjusting for potential confounders, participants in the highest category of total citrus intake (> 2 servings per day) had a significantly increased risk of melanoma (OR 1·63, 95% CI 1·24-2·12) relative to those with no consumption. For individual citrus products, participants with the most orange and orange juice consumption (> 1 serving per day) had a significantly increased melanoma risk relative to those with no consumption (OR 1·79, 95% CI 1·07-2·78 and OR 1·54, 95% CI 1·10-2·10, respectively). Fair- or very fair-skinned participants with high citrus consumption had an even greater melanoma risk (OR 1·75, 95% CI 1·31-2·29).

CONCLUSIONS

High citrus consumption was associated with an increased risk of melanoma in a large, prospective, population-based cohort. Further validation of these findings could lead to improved melanoma prevention strategies.

Citrus Consumption and the Risk of Non-Melanoma Skin Cancer in the Women's Health Initiative

Simple Summary

Citrus products are rich in furocoumarins, which can increase the risk of incident non-melanoma skin cancer (NMSC) when combined with ultraviolet radiation. However, few observational studies have evaluated the link between citrus intake and NMSC incidence. The aim of this study was to determine whether citrus intake was related to the NMSC incidence in participants of the Women’s Health Initiative Observational Study. The results of this study indicated that high citrus juice consumption was associated with a higher risk of incident NMSC compared to low consumption. These findings add further evidence of the potentially carcinogenic nature of certain citrus products and highlight the need to continue investigations in identifying risk factors and mechanisms.

Abstract

Evidence from animal studies suggests that furocoumarins, compounds present in citrus products, can increase the risk of non-melanoma skin cancer (NMSC) when combined with ultraviolet radiation. The objective of this study was to determine the relationship between citrus intake and NMSC risk among postmenopausal women from the Women’s Health Initiative (WHI) Observational Study, who were aged 50–79 years at enrollment (1993–1998). The consumption of citrus fruit, citrus juice, and non-citrus fruit and juice were measured at the baseline of the study using a food frequency questionnaire (FFQ). NMSC cases (basal or squamous cell carcinomas) were self-reported during annual follow-up surveys. The outcome data used for this analysis were collected through March 2020. The relative risk (RR) for incident NMSC by citrus consumption was calculated. Among 49,007 non-Hispanic white participants, there were 8642 cases of incident NMSC. Using less than one serving of citrus juice per week as reference, the RRs and 95% confidence intervals (CI) for incident NMSC by citrus juice intake were 1.03 (0.95, 1.10) for one serving/week, 1.06 (1.00, 1.12) for two to four servings/week, 0.98 (0.90, 1.07) for five to six servings/week, and 1.08 (1.02, 1.13) for one or more serving/day (p-trend = 0.007). Subgroup analyses did not reveal meaningful associations by sun exposure variables. In conclusion, there were indications of a slightly higher risk of incident NMSC among citrus juice consumers; however, further longitudinal and mechanistic studies are needed to confirm the key risk factors.

Citrus intake and risk of skin cancer in the European Prospective Investigation into Cancer and Nutrition cohort (EPIC)

Citrus intake has been suggested to increase the risk of skin cancer. Although this relation is highly plausible biologically, epidemiologic evidence is lacking. We aimed to examine the potential association between citrus intake and skin cancer risk. EPIC is an ongoing multi-center prospective cohort initiated in 1992 and involving ~ 520,000 participants who have been followed-up in 23 centers from 10 European countries. Dietary data were collected at baseline using validated country-specific dietary questionnaires. We used Cox proportional hazards regression models to compute hazard ratios (HR) and 95% confidence intervals (CI). During a mean follow-up of 13.7 years, 8448 skin cancer cases were identified among 270,112 participants. We observed a positive linear dose-response relationship between total citrus intake and skin cancer risk (HR = 1.10, 95% CI 1.03-1.18 in the highest vs. lowest quartile; Ptrend = 0.001), particularly with basal cell carcinoma (BCC) (HR = 1.11, 95% CI 1.02-1.20, Ptrend = 0.007) and squamous cell carcinoma (SCC) (HR = 1.23, 95% CI 1.04-1.47, Ptrend = 0.01). Citrus fruit intake was positively associated with skin cancer risk (HR = 1.08, 95% CI 1.01-1.16, Ptrend = 0.01), particularly with melanoma (HR = 1.23, 95% CI 1.02-1.48; Ptrend = 0.01), although with no heterogeneity across skin cancer types (Phomogeneity = 0.21). Citrus juice was positively associated with skin cancer risk (Ptrend = 0.004), particularly with BCC (Ptrend = 0.008) and SCC (Ptrend = 0.004), but not with melanoma (Phomogeneity = 0.02). Our study suggests moderate positive linear dose-response relationships between citrus intake and skin cancer risk. Studies with available biomarker data and the ability to examine sun exposure behaviors are warranted to clarify these associations and examine the phototoxicity mechanisms of furocoumarin-rich foods.