Intermittent fasting during adjuvant chemotherapy may promote differential stress resistance in breast cancer patients

Background: Preclinical studies prove that short-term fasting secures healthy cells against chemotherapy side effects and makes malignant cells more vulnerable to them. This study aimed to examine the effects of intermittent fasting (IF) during adjuvant chemotherapy AC (doxorubicin, cyclophosphamide) protocol in breast cancer (BC) patients. Methods: Forty-eight newly diagnosed human epidermal growth factor receptor 2-negative (HER2 negative) BC patients were divided equally into two groups (24 each). The first group was recruited to fast intermittently for three consecutive days around chemotherapy for 18 h a day from 12 am to 6 pm and eats through 6 h a day from 6 pm to 12 am with permission of drinking water during fasting hours (IF group). This IF was repeated every 3 weeks for four cycles. The second group is a non-fasting (NF) group that was allowed to eat regularly. Toxicity in the two groups was compared. Hematologic, metabolic, and inflammatory parameters were measured and compared. Results: Toxicity related to the gastrointestinal tract (GIT) was reduced in the IF group. Hematologic parameters showed no significant variations between the two studied groups after cycle 4. There was a significant increase in median glucose and median insulin levels (P < 0.001 and P = 0.001, respectively) in the NF group between baseline and after cycle 4. In addition, there was a significant decrease in the median insulin level (P = 0.002) in the IF group between the two time points. Conclusion: IF throughout chemotherapy was well tolerated and decreased the toxicity of chemotherapy. Additionally, IF-improved metabolic profiles of patients may have a positive impact on the clinical efficacy of chemotherapy.