Post-diagnostic coffee and tea consumption and breast cancer survival

BACKGROUND: We examined the role of post-diagnostic coffee and tea consumption in relation to breast cancer-specific and all-cause mortality among women with breast cancer in prospective cohort studies. METHODS: We identified 8900 women with stage I–III breast cancer from 1980 through 2010 in the Nurses’ Health Study (NHS) and from 1991 through 2011 in the NHSII. Post-diagnostic coffee and tea consumption was assessed by a validated food frequency questionnaire every 4 years after diagnosis. RESULTS: During up to 30 years of follow-up, we documented 1054 breast cancer-specific deaths and 2501 total deaths. Higher post-diagnostic coffee consumption was associated with a lower breast cancer-specific mortality: compared with non-drinkers, >3 cups/day of coffee was associated with a 25% lower risk (hazard ratio (HR) = 0.75, 95% confidence interval (CI) = 0.59–0.96; P(trend) = 0.002). We also observed a lower all-cause mortality with coffee consumption: compared with non-drinkers, >2 to 3 cups/day was associated with a 24% lower risk (HR = 0.76, 95% CI = 0.66–0.87) and >3 cups/day was associated with a 26% lower risk (HR = 0.74, 95% CI = 0.63–0.87, P(trend) 3 cups/day was associated with a 26% lower risk (HR = 0.74, 95% CI = 0.58–0.95; P(trend) = 0.04). CONCLUSIONS: Among breast cancer survivors, higher post-diagnostic coffee consumption was associated with better breast cancer and overall survival. Higher post-diagnostic tea consumption may be related to better overall survival.