Although early studies suggested that
coffee consumption might increase risk of some
cancers, more comprehensive epidemiological and experimental data now generally indicate either neutral or beneficial effects. In this review, we summarize the current evidence for associations between breast, prostate, colorectal, and
liver cancers and the consumption of
coffee, and discuss the experimental evidence for potential chemopreventive mechanisms of
coffee and
coffee constituents. The epidemiological evidence consistently indicates that
coffee protects against
liver cancer, and also point toward protective effects for risk of
colorectal cancers (with relative risks of 0.50 (95% CI: 0.42-0.59) and 0.83 (95% CI: 0.75-0.92), respectively, in the most recent meta-analyses). There seems to be no association between the overall risk of breast and
prostate cancer and
coffee intake. However, for subgroups such as postmenopausal breast
cancers, advanced
prostate cancers, and breast and
prostate cancer survivors, an inverse association with
coffee intake is indicated. Potential mechanisms for chemopreventive effects of
coffee phytochemicals includes inhibition of oxidative stress and oxidative damage, regulation of DNA repair, phase II enzymatic activity, apoptosis,
inflammation, as well as having antiproliferative, antiangiogenetic effects and antimetastatic effects. The experimental evidence for effects of
coffee and
coffee constituents on each of these processes is discussed.