Coffee drinking and cancer risk: an umbrella review of meta-analyses of observational studies

Abstract

Background: Epidemiological studies on the association between coffee intake and cancer risk have yielded inconsistent results. To summarize and appraise the quality of the current evidence, we conducted an umbrella review of existing findings from meta-analyses of observational studies. Methods: We searched PubMed, Embase, Web of Science and the Cochrane database to obtain systematic reviews and meta-analyses of associations between coffee intake and cancer incidence. For each association, we estimated the summary effect size using the fixed-and random-effects model, the 95% confidence interval, and the 95% prediction interval. We also assessed heterogeneity, evidence of small-study effects, and excess significance bias. Results: Twenty-eight individual meta-analyses including 36 summary associations for 26 cancer sites were retrieved for this umbrella review. A total of 17 meta-analyses were significant at P ≤ 0.05 in the random-effects model. For the highest versus lowest categories, 4 of 26 associations had a more stringent P value (P ≤ 10 − 6). Associations for five cancers were significant in dose-response analyses. Most studies (69%) showed low heterogeneity (I 2 ≤ 50%). Three and six associations had evidence of excessive significance bias and publication bias, respectively. Coffee intake was inversely related to the risk of liver cancer and endometrial cancer and was characterized by dose-response relationships. There were no substantial changes when we restricted analyses to meta-analysis of cohort studies. Conclusions: There is highly suggestive evidence for an inverse association between coffee intake and risk of liver and endometrial cancer. Further research is needed to provide more robust evidence for cancer at other sites.

Anti-Cancer Effects of Green Tea Epigallocatchin-3-Gallate and Coffee Chlorogenic Acid

“…Several investigations revealed that tea and coffee may have different effects in some cancer types. It is noticeable that coffee may increase a risk in certain types of cancer (bladder cancer, lung cancer, and childhood leukemia) in line with the finding from aforementioned studies which examined effects of either tea or coffee, individually [ 93 ].…”

“…In addition, a recent meta-analysis of observational studies on associations between coffee intake and 26 different cancers including 364,749 cancer cases provided evidence to show that coffee intake is inversely associated with endometrial cancer, liver cancer, melanoma, oral cancer, and oral/pharyngeal cancer [ 93 ]. Additional evidence was also obtained to suggest the reduced risk of cancers of the mouth, pharynx and larynx, and skin cancer.…”

“…Conversely, the same analysis showed the conflicting result whereby a higher coffee intake was associated with an increased risk of childhood acute lymphocytic leukemia, bladder cancer, and possibly lung cancer [ 93 ]. Similarly, a more recent pooled analysis of 12 cohort studies, comprising of 2601 cases out of 501,604 participants found a significantly increased risk for bladder cancer in male smokers: when compared the consumers of >4 cups/day with the non-consumers, hazard ratios were 1.75 (CI = 1.27–2.42) for current smokers and 1.44 (CI = 1.12–1.85) for former smokers [ 94 ].…”

Coffee and hepatocellular carcinoma: epidemiologic evidence and biologic mechanisms

“…This inverse relation may simply be due to the fact that subjects with digestive disorders, chronic liver diseases, and cirrhosis reduce spontaneously their coffee consumption, because of impairment in caffeine metabolism (reverse causation bias) [71,72] . Indeed, systemic caffeine clearance correlates with liver disfunction, and its measurement, even in saliva, has been suggested as a non-invasive test to evaluate residual liver function in patients with chronic liver disease [73][74][75][76][77][78] . Moreover, in compensated cirrhotics, some authors have reported that the total overnight salivary caffeine assessment could be useful in distinguishing between viral and metabolic etiology [77] .…”

Coffee Consumption and Pancreatic Cancer Risk: A Meta-Epidemiological Study of Population-based Cohort Studies

“…As pancreatic cancer is notorious for having a poor prognosis (Bray et al, 2018), finding modifiable risk factors is paramount. While coffee is a popular beverage globally, Zhao et al, (2020) concluded that 'there is highly suggestive evidence for an inverse association between coffee intake and risk of liver and endometrial cancer.' But Tsai and Chang (2019) concluded that 'the association between coffee and pancreatic cancer is unclear.'…”