Associations of low-carbohydrate diets with breast cancer survival.

Abstract

The objective of this study was to evaluate the role of low-carbohydrate diets after breast cancer diagnosis in relation to breast cancer-specific and all-cause mortality. For 9621 women with stage I-III breast cancer from two ongoing cohort studies, the Nurses' Health Study and Nurses' Health Study II, overall low-carbohydrate, animal-rich low-carbohydrate, and plant-rich low-carbohydrate diet scores were calculated by using food frequency questionnaires collected after breast cancer diagnosis. Participants were followed up for a median 12.4years after breast cancer diagnosis. We documented 1269 deaths due to breast cancer and 3850 all-cause deaths. With the use of Cox proportional hazards regression and after controlling for potential confounding variables, we observed a significantly lower risk of overall mortality among women with breast cancer who had greater adherence to overall low-carbohydrate diets (hazard ratio for quintile 5 vs. quintile 1 [HRQ5vsQ1 ],0.82; 95% CI,0.74-0.91; ptrend =.0001) and plant-rich low-carbohydrate diets (HRQ5vsQ1 ,0.73; 95% CI,0.66-0.82; ptrend < .0001) after breast cancer diagnosis but not animal-rich low-carbohydrate diets (HRQ5vsQ1 ,0.93; 95% CI,0.84-1.04; ptrend =.23). However, greater adherence to overall, animal-rich, or plant-rich low-carbohydrate diets was not significantly associated with a lower risk of breast cancer-specific mortality. This study showed that greater adherence to low-carbohydrate diets, especially plant-rich low-carbohydrate diets, was associated with better overall survival but not breast cancer-specific survival among women with stage I-III breast cancer.