Cancer

Coffee and breast cancer

Coffee consumption is not linked to an increased risk of breast cancer overall. In pre-menopausal women, regular coffee drinking appears to be linked to a reduced risk of the disease.

• A recent meta-analysis found that coffee drinking was inversely associated with breast cancer risk (relative risk 0.94)⁷.
• The results of a French  prospective study, which followed 67,703 women for 11 years, showed no relationship between coffee or caffeine intake and breast cancer risk overall³¹.

Post Menopausal Women

Recent studies have shown no association between coffee consumption and the incidence of breast cancer in post-menopausal women.

• The main studies include large samples from French, Italian and Swedish populations followed up for 6-10 years^4-6.
• A recent meta-analysis³² of 9 cohort and 9 case-control studies suggested that increasing coffee consumption by two cups daily tended to reduce the risk of breast cancer. However, the results showed a borderline significant association between coffee consumption and reduced risk of breast cancer in the United States and Europe, but not in Asia. This difference may originate in the limited sample size of studies conducted in Asia. Furthermore, coffee consumption did not appear to be associated with an altered risk of benign breast disease and subsequent development of breast cancer.
• In addition, a recent large Dutch study found no association between coffee and the risk of breast cancer across all levels of intake, and no link with either lifestyle or body mass index (BMI)³³.
• A Swedish study of  5,929 women (2,818 cases and 3,111 controls) showed a significantly lower risk of non-hormone receptive breast cancer in heavy coffee drinkers (more than 5 cups a day) compared to those who drank less than 1 cup a day³⁴.

Pre-menopausal women

In pre-menopausal women, the consumption of regular coffee (4 cups a day) has been associated with a 38% lower risk of breast cancer (relative risk 0.62)⁴.

• In pre-menopausal women at high risk, because they carry the BRCA1 andBRCA2 mutation, the risk for breast cancer is reduced by 25-70% with daily consumption of 4-6 cups of coffee compared to non coffee drinkers. However, this beneficial effect is limited to regular coffee; it is not observed with decaffeinated coffee³⁵.
• The risk of breast cancer is also modulated by the CYP1A2 gene, and the interaction between coffee consumption and the polymorphisms A and C of this gene have been studied. Women carrying at least one C allele (AC or CC), who consume coffee, have a 64% reduced risk compared to non coffee drinkers. Coffee has no effect in women with the AA genotype³⁶.

Taken together, these data suggest that, among women with the BRCA gene mutation, high levels of coffee consumption may be related to a reduced risk of breast cancer. They also illustrate the importance of integrating individual genetic variability when assessing diet-disease associations.

Coffee and ovarian cancer

Ovarian cancer is the fifth, both most common and lethal, cancer in women in Europe². Research to date shows no association between coffee consumption and risk of ovarian cancer.

• A meta-analysis of 8 recent, well-controlled case-control studies and 3 prospective cohort studies did not find an effect of coffee consumption on the development of this cancer³⁷.

Coffee and endometrial cancer

Research suggests that coffee consumption is linked to a lower risk of endometrial cancer.

• The data from a recent meta-analysis³⁸, including 2 cohort (201 cases) and 7 case-control studies (2,409 cases), showed that coffee drinkers were 20% less likely to develop endometrial cancer than non coffee drinkers (relative risk 0.80), but there was significant heterogeneity between the studies. Compared with non drinkers, low-to-moderate coffee drinkers (1-4 cups per day) had a 13% lower risk (relative risk 0.87) of endometrial cancer and heavy drinkers  (more than 4 cups per day) had a 49% lower risk (relative risk 0.64). The risk was reduced by 7% for each additional cup of coffee per day. These data suggest an inverse relationship between coffee and endometrial cancer but the causality is unclear.
• Three more recent studies not included in the meta-analysis reached the same conclusion. They found a dose-dependent effect of coffee consumption on lower risk of endometrial cancer. In American women, those who drank more than 2 cups of coffee a day had a 29-35% lower risk of developing endometrial cancer^39,40than non coffee drinkers. Overweight Swedish women who drank coffee also had a lower risk of endometrial cancer⁴¹.
• A recent meta-analysis found a 26% reduction in the risk of endometrial cancer among coffee drinkers, compared with nondrinkers, and a reduction in risk of over 30% among heavy coffee drinkers⁷.