Low-fat dietary pattern may improve breast cancer survival
Women who follow a low-fat dietary pattern appear to have reduced breast cancer mortality, according to data from the Earlier Women’s Health Initiative Dietary Modification trial.
The trial randomly assigned 48,835 postmenopausal women with normal mammograms and had no prior breast cancer to a dietary intervention with goals of reducing fat intake to 20 percent of energy and increasing consumption of fruits, vegetables and grains (n=19,541), or to a usual diet comparison (n=29,294).
A total of 1,764 incident breast cancers were reported during the 8.5-year dietary intervention. Fewer breast cancer-related deaths occurred in the low-fat diet group than in the usual diet group (27 vs 61 deaths; hazard ratio [HR], 0.67; 95 percent CI, 0.43 to 1.06), although the difference was not significant (p=0.08). On the other hand, the number of deaths after breast cancer significantly differed, in favour of the low-fat diet group (40 vs 94 deaths; HR, 0.65; 0.45 to 0.94; p=0.02).
During the 16.1-year follow-up, with 3,030 incident breast cancers, the number of deaths after breast cancer was also significantly lower in the low-fat vs usual diet group (234 vs 443 deaths; HR, 0.82; 0.70 to 0.96; p=0.01).
Participants who followed a low-fat dietary pattern particularly achieved a significant reduction in fat intake and body weight (p<0.001 for all).
Dietary intervention through a low-fat diet is believed to restore insulin sensitivity and reverse insulin's tumour-promoting effects, given that insulin resistance commonly results from obesity. Previous studies have shown that chronically increased concentrations of insulin may induce tumour growth and that insulin resistance may promote breast cancer development. [Am J Clin Nutr 2007;86:878S-881S]