The Effects of Protein Restricted Diet and Physical Activity on Preoperative Tumor Characteristics and Progression in Stage I-II Breast Cancer Cases: A Randomized Clinical Trial

Abstract Introduction This study investigated short-term changes in tumor characteristics and progression in patients with early-stage breast cancer between diagnosis and surgery using a protein-restricted diet and physical exercise intervention. Materials and methods Eighty patients diagnosed with breast cancer and clinically stage I-II at study entry were divided into two groups. The intervention (study) group were given an isocaloric protein-restricted (7%) diet and 10,000-step walking exercise every three days. The patients in the control group were also given an isocaloric diet but protein content was 21% and they did not undergo exercise intervention. Serum biomarkers, including Insulin Like Growth Factor-1 (IGF-1), Tumor Necrosis Factor alpha (TNFα), Fibroblast Growth Factor (FGF), Vascular Endothelial Growth Factor (VEGF), insulin, and sex hormones were measured in all participants on the morning of the first day of the diet and the morning of the surgery day; the duration between these two time points was approximately 14 days in both groups. In addition, tumor diameters and histopathological Ki-67 expression ratios were compared before and after the diet. Results The results were compared separately within the ER (+), PR (+), HER2 (-), Luminal A, and Luminal B HER2 (-) subgroups. The tumor diameters and Ki-67 ratios of patients in the control group had increased in the two weeks before surgery. However, there was no significant increase in tumor diameter or Ki-67 ratio in the study group over the same durtion. Furthermore, in the study group there was a notable decrease in the levels of IGF-1, TNFα, and VEGF. Conclusion A prolonged delay from diagnosis to surgery in patients with breast cancer may adversely affect prognosis. In situations such as the COVID-19 pandemic, preoperative herpes labialis infection, and upper respiratory tract infection, when delay may occur, introducing a protein-restricted diet with additional physical activity may mitigate the negative impact on prognosis.