Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women's Intervention Nutrition Study.

Study answer

What this study found

Dietary fat reduction achieved in the intervention group with lower fat intake than controls; at 12 months, fat grams/day were 33.3 vs 51.3 (P<.001). After median ~60 months, relapse-free survival favored the dietary group (277 relapse-free events: 96/975 vs 181/1462); HR 0.76 (95% CI 0.60–0.98); P = .034 for the adjusted Cox model (P = .077 for stratified log-rank). This corresponds to about a 24% lower risk of relapse. Stronger effect observed in ER-negative cancers (HR 0.58) than ER-positive (HR 0.85), but the interaction was not statistically significant. No difference in overall…

Study & population

Phase III multicenter randomized trial; 2,437 women with histologically confirmed, resected unilateral early-stage breast cancer; ages 48–79; conventional breast cancer management; randomized 60% to control and 40% to dietary intervention; intention-to-treat analyses; median follow-up ~60 months; primary endpoint relapse-free survival; analyses used…

Intervention

Low-fat eating plan designed to reduce percentage of calories from fat to 15% while maintaining nutritional adequacy.

Key limitation

Interim analysis; results may change with longer follow-up.

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Original abstract