The goal of this study is to explore the efficacy and safety of hyperbaric oxygen in the neoadjuvant treatment of hormone receptor positive breast cancer patients

Inclusion Criteria:

1. understood the study process, volunteered to participate in this study and signed an informed consent form
2. Patients with histopathologically confirmed diagnosis of initial unilateral primary invasive breast cancer, occult breast cancer, Inflammatory breast cancer and eczema-like carcinoma are excluded.
3. Female, aged ≥ 18 years and ≤ 60 years.
4. Patients who meet the inclusion criteria of neoadjuvant therapy to receive neoadjuvant therapy for breast cancer (locally advanced breast cancer (AJCC Stage III, except T3N1M0), or operable, but do not meet the conditions of breast conservation or axillary preservation (Stage IIA-IIB and T3N1M0).
5. Hormone receptor-positive breast cancer (Luminal/HER2-low (IHC 2+/FISH-negative)).
6. ECOG performance status 0-1.
7. LVEF ≥ 55 per cent
8. Adequate bone marrow functional reserve: white blood cell count ≥ 3.0 x 109/L, neutrophil count ≥ 1.5 x 109/L; platelet count ≥ 100 x 109/L; haemoglobin ≥ 90g/L;
9. AST, ALT ≤ 2.5 times the upper limit of normal value, alkaline phosphatase ≤ 2.5 times the upper limit of normal value, total bilirubin ≤ 1.5 times the upper limit of normal value; serum creatinine ≤ 1.5 times the upper limit of normal value
10. For non-menopausal or non-surgically sterilised female patients: consent to contraception during treatment and for at least 7 months after the last dose of study treatment

Exclusion Criteria:

1. have contraindications to hyperbaric oxygen therapy: lung disease (severe chronic obstructive airway disease, herpetic lung disease, acute or chronic lung infections, uncontrolled asthma, untreated pneumothorax), previous history of middle ear surgery, middle ear disease (eustachian tube dysfunction\recurrent vertigo), eye disease (retinal detachment).
2. Previous hyperbaric oxygen therapy.
3. Distant metastases, including lymph node metastases in the contralateral breast and mediastinum.
4. Malignancy other than radically treated basal or squamous cell carcinoma of the skin or CIS of the uterine cervix within the last two years.
5. Pregnancy or lactation.
6. Uncontrolled hypertension, cardiac, hepatic, renal related diseases or other medical or psychiatric disorders.
7. Major surgical procedures unrelated to breast cancer within 4 weeks prior to randomisation, or patients who have not fully recovered from such surgical procedures.
8. Serious or uncontrolled infections that may interfere with study treatment or assessment of study results, including but not limited to active hepatitis virus infection, human immunodeficiency virus (HIV) antibody positivity, pulmonary infection, or other infections.