Elevated blood sugar, insulin, insulin-like growth factor 1 (IGF-1), and inflammation levels are known risk factors for breast cancer and its recurrence. A calorie restricted diet improves all of these markers. Calorie restriction without malnutrition has been shown to extend the cancer-free lifespans of mammary tumor-prone laboratory animals. Normal cells deprived of nutrients as a result of fasting enter a dormant state, whereas cancer cells attempt to keep growing and dividing, exposing them to treatment. Fasting has been shown to help protect normal cells from the toxic effects of chemotherapy while sensitizing cancer cells to the treatment. Now a new study has reported that calorie restriction heightens the treatment effects of radiotherapy in triple negative (ER-/PR-/HER2-) tumors, in part by altering the biology of the cancer cells.
Latest research shows how calorie restriction can heighten treatment effects
The study referenced at the beginning of this news story was designed to investigate whether calorie restriction could be used to enhance the cytotoxic effects of radiation treatment in triple negative breast cancer by modifying its molecular profile. To conduct the study, the authors used two mouse models of breast cancer. Significant tumor regression was observed with either radiation or diet modification; combining the two increased the regression. The authors test two methods of diet modification: (1) a daily 30% reduction in total calories; and (2) alternate day feeding. It was found that calorie reduction diet resulted in greater tumor regression than intermittent fasting.
Tumors treated with calorie restriction plus radiation displayed less proliferation and more programmed cell death (apoptosis) at the molecular level. The authors also demonstrated that the insulin-like growth factor 1 receptor (IGF-1R) pathway plays a key role in achieving this physiologic responseómultiple members of the IGF-1R pathway (including IGF-1R, IRS, PIK3ca and mTOR) were downregulated. The authors conclude that use of calorie restriction has the potential to alter the biology of triple negative tumors in a way that heightens treatment effects.