Types of carbohydrate intake and breast cancer survival

Objective: To investigate the associations of different types of carbohydrate intake after breast cancer diagnosis with breast cancer-specific and all-cause mortality.

Methods: We prospectively assessed post-diagnostic intake of total sugar, added sugar, and natural sugar as well as carbohydrate from different sources, among 8932 women with stage I-III breast cancer that were identified in the Nurses' Health Study from 1980 to 2010 and Nurses' Health Study II from 1991 to 2011. Participants completed a validated food frequency questionnaire every four years after diagnosis and were followed up for death.

Results: We prospectively documented 1071 deaths due to breast cancer and 2532 all-cause deaths, over a mean of 11.5 years of follow-up. After adjustment for confounding variables, greater post-diagnostic total sugar intake was suggestively associated with greater risk of breast cancer-specific mortality [hazard ratio (HR)_Q5vsQ1 = 1.16, 95% confidence interval (CI ) = 0.95-1.41; P_trend = 0.02] and significantly associated with greater risk of all-cause mortality (HR_Q5vsQ1 = 1.23, 95% CI = 1.08-1.41; P_trend = 0.0001). Greater post-diagnostic added sugar intake was significantly associated with greater risk of all-cause mortality (HR_Q5vsQ1 = 1.20, 95% CI = 1.06-1.36; P_trend = 0.001). Post-diagnostic natural sugar (occurring in foods and not added as an ingredient) intake was not associated with mortality risk. Greater post-diagnostic fructose intake was significantly associated with greater risk of breast cancer-specific mortality (HR_Q5vsQ1 = 1.34, 95% CI = 1.10-1.64; P_trend = 0.005) and all-cause mortality (HR_Q5vsQ1 = 1.16, 95% CI = 1.02-1.32; P_trend = 0.01). High post-diagnostic intake of sucrose was associated with higher risk of breast cancer-specific and all-cause mortality. Increased post-diagnostic intake of carbohydrate from fruit juice was significantly associated with higher risk of breast cancer-specific and all-cause mortality and carbohydrate from vegetables was significantly associated with lower risk of all-cause mortality. High post-diagnostic intake of carbohydrate from potatoes was suggestively associated with higher risk of breast cancer-specific mortality and carbohydrate from refined grains was suggestively associated with higher risk of all-cause mortality.

Conclusions: We found that higher total sugar intake, especially added sugar, sucrose, and fructose, as well as carbohydrate from fruit juice after a breast cancer diagnosis were associated with poorer prognosis. High post-diagnostic intake of carbohydrate from vegetables was associated with reduced risk of mortality.