Cutting carbs may reduce IGF1 breast cancer recurrence

A reduced-carbohydrate diet may reduce breast cancer recurrence in women whose tumor tissue is positive for insulin-like growth factor-I (IGF1) receptor, according to a new study in Cancer Epidemiology Biomarkers & Prevention.

Researchers at Dartmouth performed a nested case-control study of 265 postmenopausal breast cancer survivors. The primary breast cancer tissue of each participant was stained to determine IGF1 receptor status. Carbohydrate intake from baseline to 1 year of study was estimated through 24-hour dietary recalls. Each breast cancer recurrence case (n = 91) was matched to 2 control cases (n = 174) on disease and study characteristics and counter-matched on change in carbohydrate intake. 

Half of the studied tumors were IGF1 receptor-positive. Increased risk of recurrence was tied to IGF1 receptor-positive status (hazard ratio [HR] 1.7; 95% confidence interval [CI], 1.2–2.5). Stable or increased carbohydrate intake was separately linked to an increased risk of recurrence (HR 2.0; 95% CI, 1.3–5.0). A borderline significant interaction was found between the 2 variables (P = 0.11). For women found to be receptor-negative, there was no significant increase in the risk of cancer recurrence associated with a steady or increased carbohydrate intake. However, in women who were IGF1 receptor-positive, the recurrence risk was increased by more than 5-fold with steady or increased carbohydrate consumption (HR 5.5; 95% CI, 1.8–16.3).

The investigators concluded that reducing carbohydrate consumption in breast cancer survivors who are positive for the IGF1 receptor could reduce the chances of disease recurrence. They stressed, however, that the findings in the study required replication in a larger sample.