Fasting on Newly Diagnosed Breast Cancer

This study is to see how safe the use of short-term fasting is in breast cancer patients who will receive chemotherapy before undergoing surgery and to examine if the use of short-term fasting will decrease the side effects of chemotherapy and how much a tumor shrinks while receiving chemotherapy.

Patients will fast 24 hours before and 24 hours after the administration of chemotherapy which will consist of doxorubicin plus cyclophosphamide every 2 weeks for four cycles followed by paclitaxel every 2 weeks for four cycles (dose-dense AC + T) or docetaxel (T) every 3 weeks for four cycles. Trastuzumab (H) and Pertuzumab (P) will be given concurrently with docetaxel for a total of 4 cycles before surgery. For patients who do not achieve pathological complete remission (pCR), adjuvant chemotherapy with doxorubicin (A) plus cyclophosphamide (C) every 3 weeks for four cycles will be given, followed by trastuzumab every 3 weeks to complete 1 year of treatment. For patients with pCR, only trastuzumab every 3 weeks will be given adjuvantly to complete 1 year of treatment (TPH + AC).

Eligibility Criteria:
Inclusion Criteria:

* Patients ≥ 18 years of age with histologically, and radiographically confirmed non-metastatic breast cancer with minimal tumor size over 1 cm (≥T1c lesion) to receive neoadjuvant chemotherapy recommended by the treating physician
* For estrogen receptor (ER) strongly positive, human epithelial receptor (HER2) negative breast cancer, Oncotype Dx study is required. Patients with low recurrence score will be excluded in the study.
* Eastern Cooperative Oncology Group (ECOG) performance status score \< 1
* Absolute neutrophil count \> 1500 mm3, platelet count ≥ 100×109 L, hemoglobin ≥ 8.5 g/dL
* Serum creatinine ≤1.5 times the upper limit of the normal range, total bilirubin ≤ 1.5 X ULN (≤ 3 mg/dL if clinically diagnosed with Gilbert syndrome) AST/ALT ≤ 2.5 X ULN (AST/ALT ≤ 5X ULN if clinically diagnosed with Gilbert syndrome)
* Willing to provide blood samples for correlative research purposes
* Women of child-bearing potential (i.e., women who are pre-menopausal or not surgically sterile) must be willing to use an acceptable contraceptive method (abstinence, oral contraceptive or double barrier method) for the duration of the study and for 30 days following the last dose of study drug, and must have a negative urine or serum pregnancy test within 2 weeks prior to beginning treatment on this trial.

Exclusion Criteria:

1. Uncontrolled cardiac disease, such as angina, hypertension or significant arrhythmias, congestive heart failure (NYHA grade 2 or more or LVEF \< 40% on any prior assessment). Note: Assessment of LVEF is done before and after anthracycline-based or trastuzumab-based chemotherapy as standard of care
2. Pregnant or lactating females
3. Known history of diabetes mellitus. If screening fasting glucose is ≥126 mg/dL, an HbA1C must be \< 6.5%.
4. History of syncope with calorie restriction in the past
5. Body mass index (BMI) \< 19 kg/m2
6. Clinical signs or symptoms of GI obstruction and/or requirement for parenteral hydration or nutrition
7. Inability to complete informed consent process and adhere to the protocol treatment plan and follow-up requirements
8. Concurrent severe illness such as active infection, or psychiatric illness/social situations that would limit safety and compliance with study requirements
9. Any other medical comorbidity that requires daily medication(s) that may not be safely taken without food.