Does the stimulant coffee protect against prostate cancer?

Prostate cancer in men:

In our latitudes, prostate cancer is the most common cancer in men and the second most common tumor disease with fatal outcome, as approximately 60,000 men develop the malignant tumor each year. The average age of the malignant growth in the prostate gland (i.e. prostate) is 70 years, although it is rare for the carcinoma to occur before the age of 50. As part of the male reproductive organs, the prostate's main function is to produce a secretion that is added to seminal fluid during ejaculation. The enzyme prostate specific antigen (PSA for short) is part of this secretion and dilutes the seminal fluid.

A dangerous factor of the carcinoma is that at the beginning usually no symptoms are recognizable and in the further course unspecific complaints can be felt such as pain when urinating or blood in the urine.

Does coffee have an antioxidant effect?

In addition to the alkaloid caffeine, coffee contains several other substances, including some with anti-inflammatory and antioxidant effects. So-called antioxidants (i.e. radical scavengers) can also be found in fruit and vegetables.

Studies in the past have already investigated the beneficial effects of coffee on the human metabolism. In addition to antioxidant effects, coffee could also have a positive effect on blood sugar levels, as the stimulant lowers insulin concentrations and "insulin-like growth factor 1 (IGF-1 for short)", which is currently being discussed as a growth factor in carcinogenesis.

Fluctuating results:

As early as 10 years ago, epidemiologies from the Harvard School of Public Health concluded that men who consumed 6 or more cups per day compared to men who did not drink coffee reduced the risk of disease by 18%. In contrast, there have been other studies that have actually linked coffee consumption to an increased risk of disease. A meta-study published in 2020 from Shenyang Medical University in China has now examined data from a total of 16 cohort studies (including the Harvard study). It evaluated 1,081,586 men, 57,732 of whom had prostate cancer.

Criteria for the studies were as follows:

• The study was to use a longitudinal design or a case-control design nested within a cohort study.
• Coffee consumption was determined by self-reported dietary reports or food diaries on intake amounts or frequency measurements.
• Prostate cancer was to be reported as an outcome of interest in the study. Prostate cancer was defined in the study by clinical diagnosis, physician diagnosis, medical records, or self-report.
• The study should provide risk ratio estimates with confidence intervals (CIs for short) or standard errors for the association of coffee consumption with risk of prostate cancer. The CI indicates the range that includes, with a certain probability, the parameter of a distribution a random variable. If more than one study was conducted in the same population, the reports with less applicable information were excluded.

The study results varied from a 53% decrease in the risk of disease to a 42% increase. The meta-study found a slightly protective effect. According to this, men who are more likely to consume coffee could be up to 9% less likely to develop prostate cancer. However, due to the inconsistency in the studies, this result should be interpreted with caution.

Linear dose-response relationship:

However, a linear dose-response relationship can be demonstrated according to this epidemiological study. According to this, the risk of prostate cancer could be reduced by around 1% with each daily cup of coffee. According to the study, liver, colon and breast cancer also occur less frequently than in non-coffee drinkers. Due to the overall small risk reduction, coffee drinkers are basically not protected from cancer.

Conclusion:

The meta-study suggests that increased coffee consumption may be associated with a risk reduction for prostate cancer. In any case, further studies are necessary to infer a clear causal relationship. If this assumption is subsequently proven, this finding would be a strong encouragement for many men to consume coffee in order to reduce the risk of prostate cancer.