ABSTRACT
BACKGROUND: The insulin-like growth factor-I (IGFI) receptor is a potential target for breast cancer treatment and may be influenced by dietary intake. METHODS: Nested, case-control study of 265 postmenopausal breast cancer survivors; primary breast cancer tissue was stained to determine IGFI receptor status. Change in carbohydrate intake from baseline to year 1 of study was estimated from 24-hour dietary recalls. Breast cancer recurrence cases (91) were matched to two controls (n = 174) on disease and study characteristics and counter matched on change in carbohydrate intake. Weighted conditional logistic regression models fit the risk of recurrence on IGFI receptor status and dietary change. RESULTS: Half of the tumors were IGFI receptor positive. Increased risk of recurrence was associated with IGFI receptor-positive status [HR 1.7; 95% confidence interval (CI), 1.2-2.5] and, separately, with a stable/increased intake of carbohydrates (HR 2.0; 95% CI, 1.3-5.0). There was a borderline significant interaction between those two variables (P = 0.11). Specifically, carbohydrate intake had no significant impact on risk of recurrence among women who were receptor negative, yet increased the risk of recurrence by more than 5-fold among women who were receptor positive (HR 5.5; 95% CI, 1.8-16.3). CONCLUSIONS: Among women whose tumor tissue is positive for the IGFI receptor, reducing carbohydrate intake after diagnosis could reduce the risk of breast cancer recurrence. These findings need replication in a larger sample. IMPACT: This is the first study to suggest that it may be possible to personalize dietary recommendations for breast cancer survivors based on molecular characteristics of their primary tumor tissue. .