For decades, researchers have investigated the relationship between coffee and cancer with several studies suggesting that drinking large amounts of coffee may reduce the risk for prostate cancer (1). But the mechanism behind coffee’s benefit is yet to be identified and its impact on prostate cancer progression is unknown.
A new study published in European Urology Oncology may help fill in these blanks (2).
“If you're a fast caffeine metabolizer, and you drink coffee, it may be protective in terms of prostate cancer-specific survival,” said Justin Gregg, a urologist at the University of Texas MD Anderson Cancer Center who led the study.
Gregg and his colleagues analyzed data from 5,727 people with prostate cancer who had participated in studies previously conducted by the Prostate Cancer Association Group to Investigate Cancer Associated Alteration in the Genome (PRACTICAL). Only patients with relevant data about their coffee intake, caffeine metabolism genotype, and at least six months of follow-up data were included in the study.
Gregg’s team first categorized patients by their cancer risk and genotype for the CYP1A2 enzyme, which indicates how quickly their bodies break down caffeine. The team then coded patient reported coffee intake data to a common scale and stratified it into three tiers: very low (less than three cups per week), low (three cups per week to two cups per day) or high (more than two cups per day).
High coffee consumption did not significantly prolong prostate cancer survival across all patients. Only those who carried the fast caffeine metabolizer gene variant or who had localized, less aggressive cancers seemed to benefit from drinking large amounts of coffee. In fact, Gregg and his team found a significant interaction between high coffee consumption and fast caffeine metabolism.
“The finding of an association only in fast metabolizers of caffeine is interesting,” said Edward Giovannucci, an epidemiologist at the Harvard School of Public Health, who was not involved in the study. “This finding would suggest that caffeine is not the protective agent.”
In addition to caffeine, coffee is also packed with antioxidants and anti-inflammatory compounds, which may be responsible for its protective effect (3). In future studies, Gregg intends to investigate whether these compounds or others produced in the process of breaking down caffeine confer some of coffee’s protective effects.
In the meantime, he thinks the study findings can provide some solace to people with prostate cancer. It’s too early to suggest that patients drink more coffee, but at least they can safely maintain their current coffee drinking habits.
Elizabeth Platz, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, who was not involved in the study, agrees. “At this time, there’s no compelling evidence that coffee drinking adversely affects outcomes in men with prostate cancer, and based on this study, even for men who are slow caffeine metabolizers,” she wrote in an email.
Gregg cautioned that all of the patients included in the analysis were of European ancestry. That is concerning because Black/African American people are at greater risk for developing and dying from prostate cancer, and according to Gregg, are more likely to carry the slow caffeine metabolism gene. Further research, particularly in underrepresented populations, is needed to confirm his findings.
“In the future, I envision having recommendations that can be used to kind of bolster patients’ treatment,” said Gregg. “It's never going to replace standard treatment, but it has the possibility of slowing down prostate cancer, which I think would be incredibly impactful.”
References
- Liu, H. et. al. Coffee consumption and prostate cancer risk: A meta-analysis of cohort studies. Nutr and Cancer 67, 392-400 (2015).
- Gregg, J. et al. Coffee intake, caffeine metabolism genotype, and survival among men with prostate cancer. Eur Urol Oncol (2022).
- Kempf, K. et al. Effects of coffee consumption on subclinical inflammation and other risk factors for type 2 diabetes: a clinical trial. Am J Clin Nutr 91, 950-957 (2010).
