Coffee linked to better colorectal cancer outcomes

Relation

Hu Y, King M, Yuan C, et al. Association between coffee consumption after colorectal cancer diagnosis and reduced mortality.Gastroenterology. 2018;154(4):916-926.

Draft

Prospective observational study

Objective

To examine the association between coffee consumption after colorectal cancer (CRC) diagnosis and mortality.

Participant

Participants (N = 1,599) from the Nurses' Health Study (1984-2012) and the Professionals Follow-up Study (1986-2012) who were diagnosed with stage I or II CRC during the study period.

Target parameters

Semi-quantitative food frequency questionnaires (sFFQ) collected at least 6 months but not more than 4 years after diagnosis. Baseline intake before diagnosis was estimated from the last sFFQ completed before diagnosis.

Key insights

During a median follow-up of 7.8 years, there were a total of 803 deaths, 188 of which were due to CRC. Participants who consumed at least 4 cups of coffee per day had a 52% lower risk of CRC-specific death compared to non-drinkers (hazard ratio [HR]:0.48; 95% confidence interval [CI]: 0.28-0.83;Pfor trend=0.003). Those who consumed more than 4 cups per day also had a 30% reduced risk of death from any cause (HR: 0.70; 95% CI: 0.54-0.91;Pfor trend<0.001). When assessing coffee consumption before and after diagnosis, those who consistently consumed more than 2 cups per day before and after diagnosis had a 37% reduced risk of CRC-specific death (HR: 0.63; 95% CI: 0.44-0.89) and a 29% reduced risk of death from all causes (HR: 0.71; 95% CI: 0.60-0.85) compared to those who consistently drank less than 2 cups daily.

Practice implications

In this study, coffee consumption after CRC diagnosis was dose-dependently associated with a lower risk of CRC-specific mortality and all-cause mortality.

Notably, both caffeinated and decaffeinated coffee have been linked to improved outcomes. This is in contrast to another recent study of stage III CRC patients, which found a significantly reduced risk of CRC-related and all-cause deaths with caffeinated coffee consumption alone (>4 cups/day).¹

Breast cancer studies have also found links between decaffeinated coffee and reduced cancer incidence or recurrence.^2.3Some of the other compounds that may be responsible for coffee's apparent benefits include phenolic compounds (e.g. chlorogenic acids), lipids (e.g. kahweol, cafestol), polysaccharides (e.g. galactomannans, acemannans), phytoestrogens (e.g. trigonnelline), and countless other phytochemicals that provide the characteristic Directly affect hallmarks of cancer.⁴

If we look back and evaluate how coffee as a food can affect overall gastrointestinal function, its effects on gut microbiota and intestinal motility are possible mechanisms.⁵Additionally, coffee has been found to improve glucose control, and its net physiological benefits for people with metabolic syndrome or obesity have also been suggested as possible mechanisms.¹

As with all observational studies, associations may be a surrogate for other behaviors that result in benefit. Lifestyle choices appear to be particularly proven to influence outcomes in colorectal cancer survivors.⁶Based on this, there are many confusing lifestyle alternatives that are plausible specifically for this study. Perhaps those who drink more coffee do so instead of a sugary drink. Perhaps people who are very anxious naturally choose to drink less coffee. Perhaps those who don't drink coffee are more likely to be poor sleepers. Perhaps coffee drinkers move more or are at least less sedentary than non-drinkers. These surrogates can be summarized as excess energy balance, circadian disruption, and higher concentrations of endogenous catecholamines, all of which can influence outcomes. Certainly, we won't know whether coffee itself provides any benefit until there are intervention studies with randomized participants.

Nevertheless, the observation of a dose-response relationship in which higher intake correlates with better outcomes lends a little more credence to the hypothesis that coffee itself offers protection against CRC and its recurrence.⁷This is consistent with the larger data pool on coffee, where overall mortality is lower in those who drink up to 5 cups daily, largely due to lower cardiovascular risk.^8.9

Coffee is associated not only with lower recurrence of CRC, but also with lower incidence of various types of cancer, meaning it contains components with anti-cancer effects. The most consistent evidence is the association of coffee consumption with lower initial diagnosis rates of colon, endometrial and liver cancer.^10-13As metabolomics is used to decipher the role of genetic and microbiota influences on the metabolism of its components, we should gain greater insight into the exact benefits of coffee.¹⁴

From a clinical perspective, it is now clear that coffee consumption does not need to be stopped as part of cancer prevention. When a patient enjoys coffee, it is important that we honor this ritual and let them know that the data is on their side. For some patients, guilt-free inclusion of what they thought was a vice can be therapeutic in itself.