Coffee Consumption Associated with Increased Mortality of Women with Breast Cancer

Abstract

Abstract

Background:

There has been some speculation that caffeine consumption may affect breast cancer. Most case–control studies have not documented evidence of a caffeine-breast cancer incidence link; however, there has been very little analysis of the possible effects of caffeine consumption on breast cancer survival.

Methods:

We examined overall a 20-year survival of 96 women treated for breast cancer between 1990 and 1994. As part of their health history, these women were asked about coffee drinking.

Results:

Fifty-three women drank one cup a day (79.2% survival), 22 women had two cups a day (72.7% survival), and 21 women drank three or more cups a day (42.9% survival). The effect of coffee consumption on survival was significant (p=0.006, the log rank test). To exclude the effects of lymph node involvement, age at diagnosis, and smoking history, Cox regression was performed. The effect of coffee was significant (p=0.001), independent of the effects of lymph node involvement (p=0.012) and age at diagnosis (p=0.014), and unrelated to a smoking history (p=0.721).

Conclusion:

Fatigued breast cancer survivors have an abnormal proinflammatory cytokine activity, an average of 5 years after diagnosis, as well as significant serum cortisol derangements compared to other survivors. One possible interpretation of our results suggests that there is an abnormal hypothalamic–pituitary–adrenal axis functioning in breast cancer patients with persistent fatigue, who might be using coffee to self-medicate. In other words, coffee consumption in the present study might be a surrogate marker for fatigue. Because of the paucity of data regarding caffeine intake, poor sleep, fatigue, and breast cancer survival, further studies could be worthwhile.