Coffee And The Pancreas

"Coffee...the favorite drink of the civilized world."---Thomas Jefferson

On March 12, 1981, the New England Journal of Medicine published the following study and ignited a media firestorm.

In this case-control study, 369 patients with pancreatic cancer from 11 academic medical centers in Boston and Rhode Island were interviewed about their consumption of alcohol, tobacco, tea and coffee. 644 control patients were also interviewed. The study found a strong correlation between coffee consumption and pancreatic cancer diagnosis, even after controlling for cigarette smoking. The risk increased in a linear fashion with the more coffee consumed.

Relative risk for both sexes was 1.8 drinking up to 2 cups of coffee daily, rising to as high as 3.3 for women who drank 3-4 cups of coffee daily. Even more surprising was the finding that alcohol consumption played essentially no role in the development of pancreatic cancer. The lead author of the study, who chaired the Department of Epidemiology at Harvard School of Public Health, concluded that, while more study was warranted as to the causes of pancreatic cancer, "coffee use might account for a substantial proportion of the cases of this disease in the United States."

This study was widely reported in the NY Times, Newsweek, Time Magazine and The Washington Post. Coffee drinkers and industry groups pushed back loudly. By June 1981, the study had been criticized as flawed by prominent voices in epidemiology, including Dr. Thomas Chalmers from Mount Sinai School of Medicine, who called it "unintentionally biased". In August 1981, Feinstein et al. published a commentary in JAMA that highlighted the inherent risks of case-control studies, the possible biases, and the admonition to avoid "fishing expeditions" to arrive at cancer causality. However, the bell had been rung and doubt was cast in the public mind.

So, Tell Me About Coffee

Coffee drinking is exceedingly common. According to the 2022 National Coffee Data Trends report, 66% of Americans drink coffee daily (the next most popular beverage is bottled water at 54%). According to another survey conducted in 2023, 42% of coffee drinkers would rather give up their social media instead of giving up coffee. 7 in 10 Americans drink coffee every week and 62% drink coffee every day (consuming, on average, 3 cups per day). Clearly Americans love coffee. But what exactly are people drinking in their cups of Java?

Coffee is a complex beverage containing more than 1000 described phytochemicals. Many of these compounds have therapeutic potential with antioxidant, anti-inflammatory, anti-fibrotic, and anticancer effects. Some compounds increase with roasting and some disappear altogether. Officially, the main constituents of coffee are caffeine, tannin, fixed oil, carbohydrates, and proteins in the following amounts: 2–3% caffeine, 3–5% tannins, 13% proteins, and 10–15% fixed oils. The chart below reveals the many other compounds in coffee. Impressive.

Flavonoids such as catechin, epicatechin, and quercetin in coffee likely contribute to its possible anti-cancer properties.

So, What About Coffee And Cancer, Especially Pancreatic Cancer?

78 metanalyses, cohort and prospective studies have been published from 2010 to 2021 showing that coffee drinking likely prevents cancer. For example, a metanalysis published in 2017 of 21 prospective studies showed a 10% reduction in post-menopausal breast cancer risk among coffee drinkers. Another metanalysis of 37 studies involving over 59000 patients with breast cancer showed that the risk of breast cancer decreased by 2% for each 2 cups/day increase in coffee consumption. Many other studies have shown benefits in everything from esophageal cancers to brain cancers.

Although caffeine has been shown to have anticancer activity both in vivo and in vitro, many epidemiological studies have published evidence indicating that the risk of cancer decreased even in people who ingested decaffeinated coffee. In addition, higher doses of coffee have been shown to have higher benefits in terms of risk reduction.

Does this also extend to the pancreas despite the contrarian results published in 1981? Three large metanalyses suggest that, in fact, coffee consumption can prevent pancreatic cancer too.

One study, published in 2011 by Dong et al., was a metanalysis of 14 studies which included 671,080 individuals over a 14.9 year follow-up. Compared with individuals who did not drink or seldom drank coffee per day, the pooled RR of pancreatic cancer was 0.82 (95% CI: 0.69-0.95) for regular coffee drinkers, 0.86 (0.76-0.96) for low to moderate coffee drinkers, and 0.68 (0.51-0.84) for high drinkers. This effect seemed to be limited to male coffee drinkers however.

Another study, published in 2016 by Ran et al., was a metanalysis of 20 cohort studies of 1341876 patients from the US, Japan, and Europe. The overall relative risk (RR) for highest coffee consumption versus lowest coffee consumption was 0.75 (95% Confidence Interval (CI), 0.63-0.86).

Finally, a third metanalysis in 2018 by Tian-Dong et al. evaluated 13 high-quality cohort studies, involving 959,992 patients. Comparing the highest with lowest categories of coffee intake, the pooled relative risk (RR) was 1.08 (95% CI 0.94–1.25). For dose–response analysis, no evidence of a nonlinear dose–response association between coffee consumption and pancreatic cancer was found.

Obviously metanalyses of cohort studies are good but prospective studies are even better. One large prospective trial was published as part of the NIH-AARP Diet and Health Study in 2015. The study population was 457366 US adults with a mean age of 62 years.

In this group, 1541 primary pancreatic cancers occurred. Although models adjusted only for age and sex suggested a statistically significant higher risk of pancreatic cancer with higher coffee intake, the association was substantially attenuated after extensive adjustment for smoking. Following detailed adjustment for tobacco smoking history, risk estimates for coffee drinking were not statistically significant; compared with never drinkers of coffee, the hazard ratios (95% CI) were 1.05 (0.85–1.30), 1.06 (0.86–1.31), 1.03 (0.85–1.25), 1.00 (0.79–1.25), and 1.24 (0.93–1.65) for <1, 1, 2–3, 4–5, and ≥6 cups per day, respectively.

In another large prospective trial, the UK Million Women Study, 309,797 women who never smoked with a mean age of 59.5, were followed for a median of 13.7 years. During this period, 962 cases of pancreatic cancer were diagnosed. After adjustment for potential confounding factors, including body mass index and alcohol consumption, RRs of pancreatic cancer in never‐smokers who reported usually consuming 1–2, 3–4, and ≥ 5 cups of coffee daily, compared to nondrinkers of coffee, were 1.02 (CI 0.83–1.26), 0.96 (0.76–1.22), and 0.87 (0.64–1.18), respectively. The study found little or no statistically significant association between coffee consumption and pancreatic cancer risk in never smokers.

Conclusions

Two large surveys done in the last 10 years support the old notion about coffee consumption. Only 25%, a relevant minority of consumers, think that drinking coffee could have beneficial effects on health. A survey performed by the World Cancer Research Fund (WCRF) revealed that as many as 36% of health professionals think drinking coffee increases the risk of cancer. Both of these ideas should be discarded.

Data about one of the four most commonly consumed beverages in the world suggest that coffee use either has no effect at all on cancer development or is in fact anti-carcinogenic. Drinking up to four cups of coffee daily could be used not only for its well-known taste and stimulant, pleasurable effects, but also for social, pharmaceutical, and clinical purposes, as it provides health benefits and significant effects on cancer development. The benefits extend to decaf or regular, French press or filtered, iced or hot.

And whatever happened to Dr. Brian MacMahon, who published that paper that started all this kerfuffle in 1981? In 1986, his group published additional data that failed to confirm the association between pancreatic cancer and coffee drinking! He remained the Chair of Epidemiology at Harvard School of Public Health until 1988, when he retired.