Coffee Consumption and Melanoma: A Systematic Review and Meta-Analysis of Observational Studies

Coffee consumption, cancer, and healthy aging: epidemiological evidence and underlying mechanisms

This comprehensive review examines the role of coffee consumption in promoting healthy aging and its potential impact on cancer prevention. Previous research has shown that moderate coffee intake may contribute to extending healthspan and enhancing longevity through beneficial effects on cardiometabolic health and key biological processes involved in aging. However, the relationship between coffee consumption and cancer risk remains controversial. This review synthesizes longitudinal observational and interventional data on the effects of coffee consumption on overall and site-specific cancers, explores underlying biological mechanisms, and discusses clinical and public health implications. Additionally, the review highlights evidence from Mendelian randomization (MR) studies to assess potential causal relationships. Our findings suggest that coffee consumption is associated with a reduced risk of several cancers, including skin, liver, prostate, and endometrial cancers, and may also lower cancer recurrence rates, particularly in colorectal cancer. These protective associations appear consistent across different demographic groups, with the most significant benefits observed at consumption levels of three or more cups per day. However, evidence is inconclusive for many other cancers, and coffee consumption is consistently linked to an increased risk of lung cancer. MR studies generally do not support a strong causal relationship for most cancers, though some suggest potential protective effects for hepatocellular, colorectal, and possibly prostate cancers, with mixed results for ovarian cancer and an increased risk for esophageal cancer and multiple myeloma. The protective effect of coffee on liver and prostate cancer is supported by both observational and MR studies. The potential anti-cancer benefits of coffee are attributed to its bioactive compounds, such as caffeine, chlorogenic acids, and diterpenes, which possess antioxidant and anti-inflammatory properties. These compounds may reduce oxidative stress, inhibit cancer cell proliferation, induce apoptosis, and modulate hormone levels. The review emphasizes the need for further research to clarify dose-response relationships, causal associations, and the biological mechanisms underlying these associations. While coffee consumption appears to contribute to cancer prevention and healthy aging, caution is warranted due to the increased risk of certain cancers, highlighting the complexity of its health effects.

Analysing the causal relationship between potentially protective and risk factors and cutaneous melanoma: A Mendelian randomization study

BACKGROUND

Previous observational studies reported altered melanoma risks in relation to many potential factors, such as coffee intake, smoking habits and photodamage-related conditions. Considering the susceptibility of epidemiological studies to residual confounders, there remains uncertainty about the actual causal roles of these reported factors in melanoma aetiology.

OBJECTIVES

This study aims to investigate the causal association between cutaneous melanoma (CM) and previously reported factors: coffee intake, alcohol consumption, lifetime smoking, socioeconomic status (SES), ease of skin tanning, childhood sunburn and facial ageing, providing insight into its underlying aetiology and preventative strategies.

METHODS

We utilized a two-sample MR analysis on data from the largest meta-analysis summary statistics of confirmed cutaneous melanoma including 30,134 patients. Genetic instrumental variables were constructed by identifying single nucleotide polymorphisms (SNPs) that associate with corresponding factors. Inverse variance weighted (IVW) was the primary MR method. For sensitivity and heterogeneity, MR Egger, weighted median, simple mode, weighted mode and MR Egger intercept tests were examined.

RESULTS

Cutaneous melanoma risks were found to be elevated in association with a predisposition towards ease of skin tanning (IVW: OR = 2.842, 95% CI 2.468-3.274, p < 0.001) and with childhood sunburn history (IVW: OR = 6.317, 95% CI 4.479-8.909, p < 0.001). Repeated MR after removing potential confounders and outliers demonstrated resolved horizontal pleiotropy and statistically significant results that closely mirrored the initial findings. Other potential factors, such as coffee intake, alcohol consumption, smoking and socioeconomic status (SES), indicated insignificant effects on melanoma risk in the analysis, and therefore, our Mendelian randomization study does not support their roles in modifying melanoma risks.

CONCLUSIONS

Our extensive MR analysis provides strong evidence of the causative role of ease of skin tanning and childhood sunburn history in elevating melanoma risk. Curtailing ultraviolet radiation (UVR) exposure may be the single best preventative strategy to reduce melanoma risk.

Advances in Relationship Between Alcohol Consumption and Skin Diseases

Throughout history, alcohol consumption has been an integral part of human culture. Alcohol consumption, alcoholism in particular, influences the onset and progression of liver diseases, neurological disorders, and multiple types of cancer. However, the role of alcohol consumption in influencing skin diseases has often been overlooked. In this review, we present the progress of research investigating the effects and potential mechanisms of action of alcohol consumption on acne, rosacea, psoriasis, atopic dermatitis, melanoma, and non-melanoma skin cancer.

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.

Nutritional Interventions for Patients with Melanoma: From Prevention to Therapy-An Update

Melanoma is an aggressive skin cancer, whose incidence rates have increased over the past few decades. Risk factors for melanoma are both intrinsic (genetic and familiar predisposition) and extrinsic (environment, including sun exposure, and lifestyle). The recent advent of targeted and immune-based therapies has revolutionized the treatment of melanoma, and research is focusing on strategies to optimize them. Obesity is an established risk factor for several cancer types, but its possible role in the etiology of melanoma is controversial. Body mass index, body surface area, and height have been related to the risk for cutaneous melanoma, although an 'obesity paradox' has been described too. Increasing evidence suggests the role of nutritional factors in the prevention and management of melanoma. Several studies have demonstrated the impact of dietary attitudes, specific foods, and nutrients both on the risk for melanoma and on the progression of the disease, via the effects on the oncological treatments. The aim of this narrative review was to summarize the main literature results regarding the preventive and therapeutic role of nutritional schemes, specific foods, and nutrients on melanoma incidence and progression.

A Decade of Research on Coffee as an Anticarcinogenic Beverage

Coffee consumption has been investigated as a protective factor against cancer. Coffee is a complex beverage that contains more than 1000 described phytochemicals, which are responsible for its pleasant taste, aroma, and health-promoting properties. Many of these compounds have a potential therapeutic effect due to their antioxidant, anti-inflammatory, antifibrotic, and anticancer properties. The roasting process affects the phytochemical content, and undesirable compounds may be formed. In recent years, there have been contradictory publications regarding the effect of coffee drinking and cancer. Therefore, this study is aimed at evaluating the association of coffee consumption with the development of cancer. In PubMed, until July 2021, the terms “Coffee and cancer” resulted in about 2150 publications, and almost 50% of them have been published in the last 10 years. In general, studies published in recent years have shown negative associations between coffee consumption and the risk or development of different types of cancer, including breast, prostate, oral, oral and pharyngeal, melanoma, skin and skin nonmelanoma, kidney, gastric, colorectal, endometrial, liver, leukemic and hepatocellular carcinoma, brain, and thyroid cancer, among others. In contrast, only a few publications demonstrated a double association between coffee consumption and bladder, pancreatic, and lung cancer. In this review, we summarize the in vitro and in vivo studies that accumulate epidemiological evidence showing a consistent inverse association between coffee consumption and cancer.

Gender-Dependent Specificities in Cutaneous Melanoma Predisposition, Risk Factors, Somatic Mutations, Prognostic and Predictive Factors: A Systematic Review

BACKGROUND AND AIM

Over the last decades, the incidence of melanoma has been steadily growing, with 4.2% of the population worldwide affected by cutaneous melanoma (CM) in 2020 and with a higher incidence and mortality in men than in women. We investigated both the risk factors for CM development and the prognostic and predictive factors for survival, stratifying for both sex and gender.

METHODS

We conducted a systematic review of studies indexed in PUB-MED, EMBASE, and Scopus until 4 February 2021. We included reviews, meta-analyses, and pooled analyses investigating differences between women and men in CM risk factors and in prognostic and predictive factors for CM survival.

DATA SYNTHESIS

Twenty-four studies were included, and relevant data extracted. Of these, 13 studies concerned potential risk factors, six concerned predictive factors, and five addressed prognostic factors of melanoma.

DISCUSSION

The systematic review revealed no significant differences in genetic predisposition to CM between males and females, while there appear to be several gender disparities regarding CM risk factors, partly attributable to different lifestyles and behavioral habits between men and women. There is currently no clear evidence of whether the mutational landscapes of CM differ by sex/gender. Prognosis is justified by a complex combination of phenotypes and immune functions, while reported differences between genders in predicting the effectiveness of new treatments are inconsistent. Overall, the results emerging from the literature reveal the importance of considering the sex/gender variable in all studies and pave the way for including it towards precision medicine.

CONCLUSIONS

Men and women differ genetically, biologically, and by social construct. Our systematic review shows that, although fundamental, the variable sex/gender is not among the ones collected and analyzed.

The Coffee-Acrylamide Apparent Paradox: An Example of Why the Health Impact of a Specific Compound in a Complex Mixture Should Not Be Evaluated in Isolation

The health implications of acrylamide in food are a matter of concern based on toxicological studies in rodents, which showed that doses of acrylamide more than 100 times higher than those estimated to result from dietary exposure in humans are carcinogenic; however, the cancer types reported in rodents are species-specific, and whether these results can be extrapolated to humans is still in question. In fact, human epidemiological studies revealed a general lack of association between dietary acrylamide exposure and the incidence of different cancer types. Even occupational exposure to acrylamide, resulting in acrylamide exposure nearly 10 times higher than dietary exposure, did not increase tumor occurrence. Furthermore, the consumption of coffee, which is a main contributor of dietary acrylamide exposure, actually decreases the overall incidence of cancer in humans and afford global health benefits, increasing both lifespan and healthspan on ageing. This paradox clearly illustrates the risk of evaluating an individual molecule independently of its complete food matrix, which may have other components that completely override the effects of the considered molecule.

Dietary compounds and cutaneous malignant melanoma: recent advances from a biological perspective

Cutaneous malignant melanoma is a heterogeneous disease, being the consequence of specific genetic alterations along several molecular pathways. Despite the increased knowledge about the biology and pathogenesis of melanoma, the incidence has grown markedly worldwide, making it extremely important to develop preventive measures. The beneficial role of correct nutrition and of some natural dietary compounds in preventing malignant melanoma has been widely demonstrated. This led to numerous studies investigating the role of several dietary attitudes, patterns, and supplements in the prevention of melanoma, and ongoing research investigates their impact in the clinical management and outcomes of patients diagnosed with the disease. This article is an overview of recent scientific advances regarding specific dietary compounds and their impact on melanoma development and treatment.

Coffee consumption and risk of nonmelanoma skin cancer: a dose-response meta-analysis

Several epidemiological studies have evaluated the associations between coffee consumption and the risk of skin cancer; however, the results were not conclusive. This systematic review and meta-analysis of the cohort and case-control studies was carried out to determine the association between coffee intake and the risk of nonmelanoma skin cancer. Studies were identified by searching the PubMed and MEDLINE databases (to November 2015). Study-specific risk estimates were pooled under the random-effects model. We separately estimated the relative risk of the three conditions, for exposure to different doses of coffee consumption, kind of study design, and analysis restricted to the basal cell carcinoma type. The summary relative risks for nonmelanoma skin cancer were 0.96 [95% confidence interval (CI): 0.92-0.99] for one cup of coffee, 0.92 (95% CI: 0.88-0.97) for one to two cups of coffee, 0.89 (95% CI: 0.86-0.93) for two to three cups of coffee, and 0.81 (95% CI: 0.77-0.85) for more than three cups of coffee per day, respectively. This meta-analysis suggested that caffeinated coffee might have chemopreventive effects against basal cell carcinoma dose dependently. However, other prospective studies are warranted to confirm these effects.

An Epidemiological Review of Diet and Cutaneous Malignant Melanoma

Incidence of cutaneous malignant melanoma has continued to rise despite public efforts to promote sun protection behaviors among populations at risk. However, dietary factors may also affect the development of melanoma. In the past few decades, findings from epidemiologic and experimental research have linked consumption of several foods and other nutrients to the risk of melanoma. Caffeine has been associated with a lower risk of melanoma, and citrus fruits and alcohol with increased risk. Associations between polyunsaturated fatty acid, niacin/nicotinamide, folate, and vitamin D with melanoma remain controversial. Diet likely influences melanoma development through several potential mechanisms, such as enhancing UV-induced apoptosis and increasing photosensitivity. We conducted a narrative review to summarize recent epidemiologic studies of diet and melanoma based on published literature. Given the high prevalence of the food items and nutrients covered in this review and the decades-long rising melanoma incidence worldwide, the associations we discuss may have important public health implications in terms of reducing melanoma incidence through dietary modification. Cancer Epidemiol Biomarkers Prev; 27(10); 1115-22. ©2018 AACR.

Prospective Study of Coffee Consumption and Cancer Incidence in Non-White Populations

Background: Coffee intake has been associated with risk of various cancers, but the findings, mostly from studies in white populations, are inconsistent. We examined the association of coffee consumption with overall cancer incidence and specific cancer sites in a large prospective study of African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites.Methods: 167,720 participants of the Multiethnic Cohort Study in Hawaii and Los Angeles were included. Baseline coffee intake was assessed by a validated food-frequency questionnaire. HRs and 95% confidence intervals (CIs) for sixteen cancers associated with coffee intake were calculated using Cox regressions.Results: During a mean follow-up of 15.3 years, 34,031 incident cancer cases were identified among study participants. Coffee intake was associated inversely with liver (≥4 cups/day vs. none: HR = 0.57; 95% CI, 0.38-0.87; P_trend < 0.001), ovarian (HR = 0.33; 95% CI, 0.17-0.65; P_trend = 0.007), and thyroid (HR = 0.44; 95% CI, 0.23-0.87; P_trend = 0.007) cancers and melanoma (HR = 0.72; 95% CI, 0.52-0.99; P_trend = 0.002). Coffee intake was also inversely associated with endometrial cancer among women with a body mass index >30 kg/m² (HR = 0.31; 95% CI, 0.14-0.72; P_trend = 0.04). The associations were similar across five ethnic groups (P_{heterogeneity} > 0.06) and were mainly observed among those who drank caffeinated coffee.Conclusions: On the basis of our prospective data in diverse populations, we found a decreased risk of liver, ovarian, thyroid, and endometrial cancers and melanoma associated with higher coffee intake.Impact: These results suggest that coffee drinking may protect against liver, ovarian, thyroid, and endometrial cancers, and melanoma. Cancer Epidemiol Biomarkers Prev; 27(8); 928-35. ©2018 AACR.

Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes

Objectives To evaluate the existing evidence for associations between coffee consumption and multiple health outcomes.Design Umbrella review of the evidence across meta-analyses of observational and interventional studies of coffee consumption and any health outcome.Data sources PubMed, Embase, CINAHL, Cochrane Database of Systematic Reviews, and screening of references.Eligibility criteria for selecting studies Meta-analyses of both observational and interventional studies that examined the associations between coffee consumption and any health outcome in any adult population in all countries and all settings. Studies of genetic polymorphisms for coffee metabolism were excluded.Results The umbrella review identified 201 meta-analyses of observational research with 67 unique health outcomes and 17 meta-analyses of interventional research with nine unique outcomes. Coffee consumption was more often associated with benefit than harm for a range of health outcomes across exposures including high versus low, any versus none, and one extra cup a day. There was evidence of a non-linear association between consumption and some outcomes, with summary estimates indicating largest relative risk reduction at intakes of three to four cups a day versus none, including all cause mortality (relative risk 0.83 (95% confidence interval 0.79 to 0.88), cardiovascular mortality (0.81, 0.72 to 0.90), and cardiovascular disease (0.85, 0.80 to 0.90). High versus low consumption was associated with an 18% lower risk of incident cancer (0.82, 0.74 to 0.89). Consumption was also associated with a lower risk of several specific cancers and neurological, metabolic, and liver conditions. Harmful associations were largely nullified by adequate adjustment for smoking, except in pregnancy, where high versus low/no consumption was associated with low birth weight (odds ratio 1.31, 95% confidence interval 1.03 to 1.67), preterm birth in the first (1.22, 1.00 to 1.49) and second (1.12, 1.02 to 1.22) trimester, and pregnancy loss (1.46, 1.06 to 1.99). There was also an association between coffee drinking and risk of fracture in women but not in men.Conclusion Coffee consumption seems generally safe within usual levels of intake, with summary estimates indicating largest risk reduction for various health outcomes at three to four cups a day, and more likely to benefit health than harm. Robust randomised controlled trials are needed to understand whether the observed associations are causal. Importantly, outside of pregnancy, existing evidence suggests that coffee could be tested as an intervention without significant risk of causing harm. Women at increased risk of fracture should possibly be excluded.

Coffee, Caffeine, and Health Outcomes: An Umbrella Review

To evaluate the associations between coffee and caffeine consumption and various health outcomes, we performed an umbrella review of the evidence from meta-analyses of observational studies and randomized controlled trials (RCTs). Of the 59 unique outcomes examined in the selected 112 meta-analyses of observational studies, coffee was associated with a probable decreased risk of breast, colorectal, colon, endometrial, and prostate cancers; cardiovascular disease and mortality; Parkinson's disease; and type-2 diabetes. Of the 14 unique outcomes examined in the 20 selected meta-analyses of observational studies, caffeine was associated with a probable decreased risk of Parkinson's disease and type-2 diabetes and an increased risk of pregnancy loss. Of the 12 unique acute outcomes examined in the selected 9 meta-analyses of RCTs, coffee was associated with a rise in serum lipids, but this result was affected by significant heterogeneity, and caffeine was associated with a rise in blood pressure. Given the spectrum of conditions studied and the robustness of many of the results, these findings indicate that coffee can be part of a healthful diet.

Caffeinated and decaffeinated coffee consumption and melanoma risk: a dose-response meta-analysis of prospective cohort studies

To determine the association between total, caffeinated and decaffeinated coffee consumption and melanoma risk a dose-response meta-analysis on prospective cohort studies were performed. Eligible studies were identified searching PubMed and EMBASE databases from the earliest available online indexing year to March 2017. The dose-response relationship was assessed by random-effects meta-analysis and the shape of the exposure-outcome curve was modelled linearly and using restricted cubic splines. A total of seven studies eligible for meta-analysis were identified that comprised 1,418,779 participants and 9211 melanoma cases. A linear dose-response meta-analysis showed a significant association between total coffee consumption and melanoma risk. An increase in coffee consumption of one cup per day was associated with a 3% reduction in melanoma risk (RR 0.97; 95% CI 0.95-0.99). Our findings suggest that coffee intake may be inversely associated with incidence of melanoma. Nevertheless, further studies exploring also the role of confounding factors are needed to explain the heterogeneity among studies.

Coffee Drinking Is Widespread in the United States, but Usual Intake Varies by Key Demographic and Lifestyle Factors

BACKGROUND

Despite widespread popularity and possible health effects, the prevalence and distribution of coffee consumption in US adults are poorly characterized.

OBJECTIVE

We sought to estimate usual daily coffee intakes from all coffee-containing beverages, including decaffeinated and regular coffee, among US adults according to demographic, socioeconomic, and health-related factors.

METHODS

Dietary intake data from ≤2 nonconsecutive 24-h dietary recalls and a food-frequency questionnaire administered during the NHANES 2003-2006 were used to estimate the person-specific probability of consuming coffee on a particular day and the usual amount consumed on consumption days. Trends in population mean coffee consumption over time were evaluated by using multiple linear regression and 1-d 24-h recall data from NHANES 2003-2012. Analyses were weighted to be representative of the US adult population aged ≥20 y.

RESULTS

An estimated 154 million adults, or 75% of the US population, aged ≥20 y reported drinking coffee; 49% reported drinking coffee daily. Prevalence did not vary by sex, education, income, or self-reported general health (all P ≥ 0.05) but did vary by age, race/ethnicity, smoking status, and alcohol drinking (all P < 0.05). Among coffee drinkers, the mean ± SE usual intake was 14.1 ± 0.5 fluid ounces/d (417 ± 15 mL/d). Mean usual intakes were higher in men than women, in older age groups than in those aged 20 to <30 y, in non-Hispanic whites than in non-Hispanic blacks or Hispanic/other races, in smokers than in never smokers, and in daily alcohol consumers than in nonconsumers (all P < 0.05). Population mean coffee consumption was stable from 2003 to 2012 (P-trend = 0.09).

CONCLUSIONS

Coffee is widely consumed in the United States, with usual intakes varying by lifestyle and demographic factors, most notably by age. Longitudinal studies are needed to determine whether observed differences by age reflect birth cohort effects or changes in drinking patterns over the lifetime.

Coffee consumption and the risk of malignant melanoma in the Norwegian Women and Cancer (NOWAC) Study

Background

Coffee contains biologically-active substances that suppress carcinogenesis in vivo, and coffee consumption has been associated with a lower risk of malignant melanoma. We studied the impact of total coffee consumption and of different brewing methods on the incidence of malignant melanoma in a prospective cohort of Norwegian women.

Methods

We had baseline information on total coffee consumption and consumption of filtered, instant, and boiled coffee from self-administered questionnaires for 104,080 women in the Norwegian Women and Cancer (NOWAC) Study. We also had follow-up information collected 6–8 years after baseline. Multiple imputation was used to deal with missing data, and multivariable Cox regression models were used to calculate hazard ratios (HR) for malignant melanoma by consumption category of total, filtered, instant, and boiled coffee.

Results

During 1.7 million person-years of follow-up, 762 cases of malignant melanoma were diagnosed. Compared to light consumers of filtered coffee (≤1 cup/day), we found a statistically significant inverse association with low-moderate consumption (>1–3 cups/day, HR = 0.80; 95 % confidence interval [CI] 0.66–0.98) and high-moderate consumption of filtered coffee (>3–5 cups/day, HR = 0.77; 95 % CI 0.61–0.97) and melanoma risk (p_trend = 0.02). We did not find a statistically significant association between total, instant, or boiled coffee consumption and the risk of malignant melanoma in any of the consumption categories.

Conclusions

The data from the NOWAC Study indicate that a moderate intake of filtered coffee could reduce the risk of malignant melanoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2586-5) contains supplementary material, which is available to authorized users.

Coffee, tea and caffeine intake and the risk of non-melanoma skin cancer: a review of the literature and meta-analysis

PURPOSE

Laboratory studies suggested that caffeine and other nutrients contained in coffee and tea may protect against non-melanoma skin cancer (NMSC). However, epidemiological studies conducted so far have produced conflicting results.

METHODS

We performed a literature review and meta-analysis of observational studies published until February 2016 that investigated the association between coffee and tea intake and NMSC risk. We calculated summary relative risk (SRR) and corresponding 95 % confidence intervals (95 % CI) by using random effects with maximum likelihood estimation.

RESULTS

Overall, 37,627 NMSC cases from 13 papers were available for analysis. Intake of caffeinated coffee was inversely associated with NMSC risk (SRR for those in the highest vs. lowest category of intake: 0.82, 95 % CI 0.75-0.89, I ² = 48 %), as well as intake of caffeine (SRR 0.86, 95 % CI 0.80-0.91, I ² = 48 %). In subgroup analysis, these associations were limited to the basal cell cancer (BCC) histotype. There was no association between intake of decaffeinated coffee (SRR 1.01, 95 % CI 0.85-1.21, I ² = 0) and tea (0.88, 95 % CI 0.72-1.07, I ² = 0 %) and NMSC risk. There was no evidence of publication bias affecting the results. The available evidence was not sufficient to draw conclusions on the association between green tea intake and NMSC risk.

CONCLUSIONS

Coffee intake appears to exert a moderate protective effect against BCC development, probably through the biological effect of caffeine. However, the observational nature of studies included, subject to bias and confounding, suggests taking with caution these results that should be verified in randomized clinical trials.

Coffee consumption and the risk of cutaneous melanoma: a meta-analysis

PURPOSE

Results from epidemiologic studies on coffee consumption and the risk of cutaneous melanoma are inconsistent. We conducted a meta-analysis to assess the associations between the consumption of total coffee, caffeinated coffee and decaffeinated coffee and the risk of cutaneous melanoma, respectively.

METHODS

A literature search was performed in PubMed, Web of Science and EMBASE for relevant articles published up to August 2015. Pooled relative risks (RRs) with 95 % confidence intervals (CIs) were calculated with a random-effects model. Dose-response relationship was assessed by restricted cubic spline.

RESULTS

Twelve studies involving 832,956 participants for total coffee consumption, 5 studies involving 717,151 participants for caffeinated coffee consumption and 6 studies involving 718,231 participants for decaffeinated coffee consumption were included in this meta-analysis. Compared with the lowest level of consumption, the pooled RRs were 0.80 (95 % CI 0.69-0.93, I (2) = 53.5 %), 0.85 (95 % CI 0.71-1.01, I (2) = 65.0 %) and 0.92 (95 % CI 0.81-1.05, I (2) = 0.0 %) for the consumption of total coffee, caffeinated coffee and decaffeinated coffee, respectively. In subgroup analysis by study design, the pooled RRs in cohort studies and case-control studies were 0.83 (95 % CI 0.72-0.97) and 0.74 (95 % CI 0.51-1.07) for total coffee consumption, respectively. Dose-response analysis suggested cutaneous melanoma risk decreased by 3 % [0.97 (0.93-1.00)] and 4 % [0.96 (0.92-1.01)] for 1 cup/day increment of total coffee and caffeinated coffee consumption, respectively.

CONCLUSIONS

This meta-analysis suggests that coffee consumption may reduce the risk of cutaneous melanoma.