Higher coffee consumption was associated with a lower risk of endometrial cancer, according to an analysis of studies published in the Journal of Obstetrics and Gynaecology Research. Researchers also found that caffeinated coffee may provide better protection than decaffeinated versions.
 
The analysis included 24 studies on coffee intake with 9,833 new cases of endometrial cancer occurring in 699,234 individuals.
 
People in the highest category of coffee intake had a 29% lower relative risk of developing endometrial cancer than those in the lowest category.
 
The authors of the analysis highlight several mechanisms that have been associated with the potential anti-cancer effects of coffee. “Further studies with large sample size are needed … to obtain more information regarding the benefits of coffee drinking in relation to the risk of endometrial cancer,” they wrote.
 
Endometrial cancer, a type of cancer that begins in the lining of uterus, is one of the most common gynecologic malignancies worldwide, with an incidence of 12.9 per 100,000 women and a mortality rate of 2.4 per 100,000.
 
Researchers noted that coffee contains many bioactive components, such as phenolic compounds. These polyphenols can increase the homocysteine concentrations in the plasma and inhibit DNA methylation in a dose-dependent manner, which prevents the downregulation of tumor suppressor proteins and DNA repair enzymes involved in carcinogenesis.
 
The meta-analysis demonstrated that females with a higher BMI had a high risk of endometrial cancer and may obtain more benefit from increased coffee drinking than those with a lower BMI.
 
Limitations of the study included:
 
1) The lack of a uniform coffee standard. Different studies focused on different types of coffee beans, different brewing methods, different coffee drinking habits, and different categories of coffee consumption.
 
2) The number of some subgroups was small. For example, only two studies comparing different brewing methods were included.

3) Confounding factors might exist in the included studies. Different histological types of endometrial cancer might lead to a different response to coffee exposure.
 
4) Due to insufficient data, effects of coffee consumption on two pathogenic types of endometrial cancer were not clarified.