Coffee consumption and risk of colorectal cancer: a meta-analysis of observational studies

Abstract

Objective: Separate meta-analyses based on case-control and cohort studies have reported different results on the relationship between coffee consumption and colorectal cancer risk. To clarify the effect of coffee intake on colorectal cancer risk, we performed a meta-analysis based on both case-control and cohort studies. Design: Review study. Setting: We identified case-control and cohort studies related to coffee consumption and colorectal cancer risk listed on MEDLINE, the Cochrane Controlled Trials Register, EMBASE, Science Citation Index and PubMed (until May 2011). In subgroup analyses using case-control studies, significant inverse associations were found in females for colorectal cancer and in Europe for colorectal and colon cancer, while the subgroup analyses of cohort studies found that coffee drinks substantially decreased risk of colon cancer only in Asian women. Conclusions: Results from case-control studies suggest coffee consumption can significantly decrease the risks of colorectal cancer and colon cancer, especially in Europe and for females. Keywords Colorectal cancer Coffee Meta-analysis Observational studiesColorectal cancer is the third most common cancer in men and the second most common in women worldwide, with over 1?2 million new cancer cases and 608 700 deaths occurring in 2008 (1) . It is well known that obesity, smoking and physical inactivity are important risk factors for colorectal cancer. However, nutritional factors such as alcohol, tea, coffee, etc. have also been considered to play an important role in the development of colorectal cancer (2) .Coffee is a complex mixture of more than a thousand chemicals, and these constituents have potential genotoxic and mutagenic properties, antioxidant and antimutagenic activities to affect colorectal cancer risk (3) . Over the last four decades, the relationship between coffee consumption and colorectal cancer risk has been extensively examined (4) . In 1990, a Working Group of the International Agency for Research on Cancer reviewed the data on coffee consumption and colorectal cancer risk and concluded that in man 'there is some evidence of an inverse relation between coffee drinking and cancer of the large bowel' (3) . However, the relationship between coffee intake and colorectal cancer risk appears inconsistent in case-control studies and cohort studies. To clarify the relationship between coffee consumption and colorectal cancer risk, Giovannucci performed a meta-analysis in 1998 and reported an overall OR/relative ratio (RR) for high v. low coffee intake of 0?72 (95 % CI 0?61, 0?84) and 0?97 (95 % CI 0?73, 1?29) after combining the results of twelve case-control studies and five cohort studies, respectively (5) . A subsequent meta-analysis (6) and a pooled analysis (7) for cohort studies showed no significant inverse associations; however, another meta-analysis in 2011 *Corresponding authors: Email

Coffee drinking and colorectal cancer risk: an evaluation based on a systematic review and meta-analysis among the Japanese population

“…In meta-analysis, summarized RR of cohort studies was nearly equal to unity, whereas summarized OR of case-control studies was statistically significantly decreased for colorectal cancer and colon cancer. The null finding among cohort studies in Japan is consistent with a recent systematic review and meta-analysis of cohort studies (RR = 0.94; 95% CI = 0.88-1.01) (16), which included eight studies from Europe, four from America and four from Asia including Japan (three studies). That meta-analysis did not detect any significant variation in association by study region (16).…”

“…In addition, we performed several sensitivity analyses, in which studies with a small number of cases, using unique cutoff of coffee consumption, or based on mortality data only were excluded. We also conducted sexspecific analysis to explore the difference in association between men and women, which has been documented in a previous meta-analysis (16). A two-sided P value <0.05 was considered SS.…”

“…Given that coffee drinking is increasingly popular in Japan (mean consumption among adults,~11 cups/week) (23), it would be of great interest to know whether coffee consumption is associated with risk of colorectal cancer in this population. A recent meta-analysis among studies worldwide reported lower risk of colon cancer associated with coffee drinking for Asian women (16). That study, however, did not include two cohort (24,25) and several casecontrol studies (26)(27)(28)(29) in Japan.…”

“…Meta-analyses of case-control studies have consistently shown that coffee consumption was significantly associated with decreased risk of colorectal cancer (16)(17)(18), whereas most (16,18,19) but not all (20) meta-analyses of cohort studies reported no association. Data included in these meta-analyses, however, were derived mainly from Westerners, who had greater body fat (21) and insulin secretion capacity (22) than Asians.…”

Association between coffee or tea drinking and Barrett’s esophagus or esophagitis: an Italian study

“…Coffee intake has been related to a lower risk of a number of cancers at different sites such as liver, prostate, breast and colorectum, [19][20][21][22][23] while it seemed to increase the risk of laryngeal cancer. 24 The studies on the role of coffee on the occurrence of esophageal diseases did not exclude a weak inverse relationship between coffee intake and esophageal cancers, 25 while a metaanalysis of some Italian observational studies provided evidence of an inverse association with cancers of the oral cavity or pharynx, but not with laryngeal and esophageal cancers.…”