The researchers examined the associations between coffee consumption and serum GGT with the risk of liver cancer. Residents of Finland drink more coffee per capita than the Japanese, Americans, Italians and other Europeans, so the scientists studied 60,323 Finnish participants ages 25 to 74 who were cancer-free at baseline.
The Finns were included in seven independent cross-sectional population surveys conducted between 1972 and 2002 and followed up through June 2006. The participants completed a mail-in questionnaire about their medical history, socioeconomic factors and dietary and lifestyle habits. For a subset of participants, clinical data was available, including serum levels of GGT. Data on subsequent cancer diagnoses was collected from the country-wide Finnish Cancer Registry.
Based on their answers to the question: "How many cups of coffee do you drink daily?", the participants were divided into five categories: zero to one cup, two to three cups, four to five cups, six to seven cups, and eight or more cups per day. After a median follow-up period of 19.3 years, 128 participants were diagnosed with liver cancer.
The researchers noted a significant inverse association between coffee drinking and the risk of primary liver cancer. They found that the multivariable hazards ratio of liver cancer dropped for each group that drank more coffee. It fell from 1.00, to .66, to .44, to .38 to .32 respectively. The biological mechanisms behind this association are not known yet, the authors point out.
They also found that high levels of serum GGT were associated with an increased risk of liver cancer. The hazard ratio of liver cancer for the highest versus lowest quartile of serum GGT was 3.13. "Nevertheless," the scientists report, "the inverse association between coffee consumption and the risk of liver cancer was consistent in the subjects at any level of serum GGT."
MEDICA.de; Source: Wiley-Blackwell