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Cancer

Coffee consumption and cancers of the digestive tract

Coffee and cancer of the oesophagus

Overall, there is little evidence for an association between oesophageal cancer risk and the amount of coffee consumed.

A literature survey pooled the data of 22 studies (17 case-control studies, 2 pooled analyses and 3 cohort studies; 14 originating from the USA and Europe), published between 1974 and 2008, looking at the relationship between the consumption of coffee and the risk of oesophageal cancer9. Most studies reported an unchanged, or reduced, risk of oesophageal cancer with the consumption of 3 or more cups of coffee a day. However, the majority of studies stated an increased risk with the increase in the temperature of hot drinks. There are however possible biases since the exact temperature of coffee, and the quantity and frequency of consumption, as well as the exact type of esophageal cancer are unknown⁹.
A recent, large meta-analysis found that coffee consumption was inversely associated with oesophageal cancer (relative risk 0.55)⁷.
A recent large Norwegian prospective study, of 389,624 middle-aged men and women followed up for over 14 years, found no relationship between coffee intake and cancer of the oesophagus.¹⁰

Coffee and stomach cancer

There appears to be no association between coffee consumption and risk of stomach cancer.

A systematic review and a meta-analysis of 23 studies¹¹ found no association between coffee consumption and the development of stomach cancer in either cohort (relative risk 1.02) or case-control studies (relative risk 0.97).

Coffee and cancer of the upper aero-digestive tract

Recent research suggests an inverse association between coffee consumption and risk of oral cavity/pharynx cancers.

A systematic meta-analysis¹² of observational studies, published between 1989 and 2009, reported a 36% reduced risk for cancers of the oral cavity/pharynx (relative risk 0.64) between highest (3-5 and more cups per day) versus lowest (up to 1 cup per day) coffee drinkers, based on a total of 2,633 cases from one cohort and 8 case-control studies. On the other hand, there was no relation between coffee consumption and laryngeal cancer. There was no significant heterogeneity across studies.
More recently, another meta-analysis found that coffee consumption was inversely associated with buccal and pharyngeal cancer (relative risk 0.49)⁷.
On the other hand, a recent large Norwegian prospective study, of 389,624 middle-aged men and women followed up for over 14 years, found no relationship between the amount of coffee consumed and the risk of cancer of the buccal cavity and pharynx¹⁰; however, the authors could not exclude a weak inverse association.

Coffee and liver cancer

Liver Function Research Review

Liver cancer is the fifth most prevalent type of cancer worldwide, and the fourteenth most prevalent in Europe². Studies looking at the relationship between coffee consumption and risk of liver cancer have found an inverse association, and coffee consumption appears to be linked to a slower progression of liver disease.

Five meta-analyses^4-7,13 reported a significant reduction in the risk of developing liver cancer. This risk reduction reached a mean value of 30% in coffee drinkers versus non coffee drinkers, with up to 55% lower risk in heavy coffee consumers (relative risk 0.45). The risk reduction reached 23% for each cup of coffee consumed daily in case-control studies and 25% in cohort studies¹³.

In addition, a case-control study in Hong Kong among chronic hepatitis B virus carriers (a group at higher risk of developing liver cancer) found that moderate coffee drinkers, who drank coffee four times a week or more, had a 59% lower risk of developing liver cancer than non-coffee drinkers. There was also a significant dose-response effect¹⁴.

Moreover, the risk of evolution of hepatitis C to cancer was found to be reduced by 22% for each cup of coffee consumed, and for at least 3 cups daily, the risk of disease progression is reduced by 62%¹⁵.

There are currently two proposed mechanisms for coffee’s association with a reduced risk of developing liver cancer and slower progression of liver disease^4,5,13,14.

Cirrhosis is a major risk factor for the development of liver cancer and coffee has been shown to inhibit the elevation of hepatic transaminases, markers of hepatic disease.
Coffee could reduce the circulating level of iron, and hence reduce the risk of hepatic carcinogenesis.
The role of antioxidants and other coffee components remains to be explored.

Coffee and cancer of the pancreas

Recent science does not support an association between coffee consumption and an increased risk of pancreatic cancer. Some, but not all, of the most recent studies suggest an inverse association.

In 1990, the International Agency for Research on Cancer (IARC) considered that the evidence for a link between coffee and pancreatic cancer was inadequate. The positive results of the first studies published in 1970 and 1981 were attributed to confounders. Moreover, the control subjects of these studies were patients who suffered gastro-intestinal problems likely to affect, i.e. reduce, their coffee consumption⁴.
Since the IARC Monograph, the report from the World Cancer Research Fund (WCRF) included a meta-analysis of 37 case-control and 18 cohort studies, which found a relative risk of 1.04 and 1.00, respectively, in coffee drinkers versus non coffee drinkers6. In other words, there was no increase in risk of developing pancreatic cancer with coffee consumption.
Since this meta-analysis, a large Japanese cohort study¹⁶, involving 102,137 participants followed over 11 years, did not observe an increased risk with coffee consumption. The study even reported a reduced risk in men consuming 3 cups of coffee daily compared to non coffee drinkers.
Recently another meta-analysis, which included 14 cohort studies looking at coffee consumption and risk of pancreatic cancer, found a significant inverse relationship (relative risk 0.82)⁷.
Another meta-analysis of 14 cohort studies, covering Europe, the United States and Japan and including 671,080 individuals (1,496 cancer events) followed up for over 14 years, also identified an inverse association between coffee drinking and risk of pancreatic cancer in men. Regular coffee drinkers had an 18% lower risk of cancer than non-drinkers; low to moderate coffee drinkers had a 14% lower risk; and high coffee drinkers had a 32% lower risk¹⁷. Overall, an additional cup of coffee per day was associated with a 4% lower risk of pancreatic cancer.
However, a further meta-analysis of 37 case-control and 17 cohort studies with 10,594 cases of pancreatic cancer showed that, overall, coffee consumption was not convincingly related to pancreatic cancer risk once smoking was taken into account, even at high intakes¹⁸.
In addition, two Italian case-control studies found no association between the quantity of coffee consumed, or the duration of exposure, and pancreatic cancer risk, suggesting that there is no causal association between coffee and pancreatic cancer¹⁹.

Coffee and colorectal cancer

There appears to be a modest, favourable effect of moderate coffee consumption on colorectal cancer risk, consistent across study designs (hospital vs. population based), geographical areas, and various confounding factors.

A meta-analysis on coffee and colorectal cancer was published in 2004²⁰. It included 3 cohort and 15 case-control studies from Japan, 8 European countries, Argentina and the USA and included 8,713 cases of cancer occurring in 147,227 subjects. The authors reported heterogeneity linked to the design of the studies. Cohort studies did not observe any association while case-control studies did generally find a relative risk below 120.
Another meta-analysis of 5 cohort and 12 case-control studies, including 6,192 cases of colorectal cancer, found a 24% lower risk (relative risk 0.76) in those with a high coffee consumption (at least 4 cups/day) compared to non-coffee drinkers²¹.
Similarly, a third recent meta-analysis²², including 24 case-control studies, reported a risk reduction of 17% in coffee drinkers compared to non coffee drinkers, with risk falling by 6% for each cup of coffee consumed, and a 30% lower risk (relative risk 0.70) of colorectal cancer in the highest consumers.
Two Japanese cohort studies including 31,550 and 96,000 subjects respectively, reported a risk reduction of 56% with 3 or more cups per day, but only in women^{23, 24}.
Recently, a fourth meta-analysis including 15 cohort studies looking at coffee consumption and colorectal cancer found an inverse association between coffee intake and the risk of colorectal cancer⁷.

Only one meta-analysis²² shows a dose-response relationship, which suggests either a threshold effect or a difference between coffee drinkers and non coffee drinkers⁴. It could indeed represent a confounding factor linked to the decrease in coffee consumption in patients after the onset of symptoms²².

The inverse association between coffee consumption and colorectal cancer risk has been attributed to a number of factors^{20-22, 25}, including:

The anti-carcinogenic properties of coffee diterpenes and antioxidants
Coffee’s capacity to induce the excretion of biliary acids and neutral sterols in the colon
The stimulation of colon motility, reducing the length of time mutagens are in contact with the intestinal mucosa
Caffeine’s inhibition of colon cancer cell growth.