Stage I HER2 Positive Invasive Breast Cancer De-escalation Study(IRIS)

Inclusion Criteria

• •Females 18-70 years old;
• •Pathological confirmed of stage I breast cancer: histologically confirmed that the longest diameter of invasive cancer is no more than 2cm and the lymph node is negative (N0);
• •In IRIS-A cohort, if a patient is HR negative(ER/PR\<10%), the longest diameter of invasive cancer could not exceed 2cm; while if a patient is HR positive(ER and/or PR ≥10%）,the longest diameter of invasive cancer is greater than 1cm and no more than 2cm;
• •In IRIS-B cohort, a patient need to be HR positive (ER and / or PR expression ≥10%) and the longest diameter of invasive cancer could not exceed 1cm;
• •The pathological type of immunohistochemistry must meet the following conditions: HER-2 (3+) or HER-2 (0-2 +) with FISH detection is amplified;
• •For patients with invasive lesions on both sides, if both lesions are HER-2 positive and meet the tumor size requirements, then can be enrolled;
• •Has adequate organ function meeting the following criteria: (1) adequate bone marrow function: hemoglobin ≥ 90 g/L (no blood transfusion within 14 days); absolute neutrophil count ≥ 1.5 x 109 /L; platelet count ≥ 100 \* 109 /L; (2)adequate liver and kidney function: Alanine Aminotransferase (ALT) ≤ 3×upper limit of normal (ULN), Aspartate Aminotransferase (AST) ≤ 3×ULN, Total Bilirubin (TBIL)≤ 1.5×ULN, serum creatinine ≤ 1×ULN#and with endogenous creatinine clearance rate of \>50 ml/min (Cockcroft-Gault formula);
• •LVEF\>50%;
• •The patient voluntarily joined the study, signed the informed consent form, had good compliance, and cooperated with the follow-up.