Since the widespread use of Halsted radical mastectomy in the early 20th century, breast cancer surgery has undergone significant changes due to a series of landmark clinical trials in the United States and Europe over the past 50 years, as well as the diversification of adjuvant therapies that have made breast cancer surgery less aggressive, thus establishing a worldwide standard of care in breast surgery that has led to significant improvements in quality of life. The following is a list of these landmark clinical trials that have led to a significant improvement in the quality of life of patients. NSABP-B04: Prior to 1890, there were no good treatment options for breast cancer. William Stewart Halsted’s proposal of radical breast cancer surgery (removal of the breast and its skin, chest muscles, and axillary lymph nodes) opened a new era in the treatment of surgical therapy for advanced breast cancer, and although focal control was achieved, long-term survival remained unsatisfactory. It was not until the 1960s that the American Surgical Adjuvant Breast and Bowel Cancer Program (NSABP) wondered whether breast cancer was systemically transmitted rather than focally, and thus in 1971 the NSABP-B04 trial was created. Experiment 1 included 1079 patients with clinical axillary lymph node-negative breast cancer from 1971-1974 who were randomized into three groups: radical breast cancer surgery, breast simple resection + postoperative radiotherapy, and mastectomy alone. Trial 2 included 586 breast cancer patients with positive axillary lymph nodes who underwent mastectomy alone + postoperative radiotherapy and compared them to patients with radical axillary lymph node-positive breast cancer. The results of the trial showed no statistical difference in disease free survival (DFS), distant metastasis free survival (DDFS), and overall survival (OS) for all subgroups at 3, 5, and 10 years, after 25 years of follow-up. The results of the 2002B-04 trial showed no statistical difference in long-term outcomes among the subgroups of the above trials either, thus concluding that radical radical mastectomy for axillary lymph node negative patients is unnecessary, as well as radiation therapy after mastectomy alone, thus shifting the treatment concept to the theory that the surgical approach does not have to be performed as thoroughly and diversified treatment. NSABP-B06: To further narrow the surgical approach and explore the feasibility of breast-conserving surgery (BCS) in early-stage breast cancer patients, the NSABP-B06 trial was born. 2,163 patients with tumors ≤100 px breast cancer were enrolled between 1976 and 1984 and randomized into the mastectomy + lymph node dissection + postoperative radiotherapy/no radiotherapy vs. modified radical mastectomy group. However, there was a statistical difference in ipsilateral tumor recurrence (IBTR) between the tumor resection and tumor resection + radiotherapy groups (39.2% vs 14.3% P < 0.001), and a higher IBTR in the no radiotherapy group at 5 years postoperatively, also statistically different (75% vs 40%). This trial tells us that BCS is a safe surgical modality for early-stage breast cancer and emphasizes the importance of postoperative radiotherapy in reducing the risk of focal recurrence, establishing breast-conserving surgery + radiotherapy as a preferred treatment modality for patients with operable stage I, II, and stage I breast cancer. MILAN I STUDY: The Milan 1 study further supports the status of BCS as a treatment for breast cancer with small masses. NSABP-B17: The value of BCS for early invasive carcinoma has been confirmed, however, can BCS also be used for treating non-invasive carcinoma?In 1988 NSABP conducted the B-17 trial to investigate the feasibility of BCS for ductal carcinoma in situ (DCIS), enrolling 818 patients randomized to mastectomy and mastectomy + radiotherapy, which showed that non invasive and invasive IBTR were significantly reduced in the group with radiotherapy, thus this trial confirmed that BCS is also an effective treatment option for non-invasive cancer. EORTC 10853: After a study similar to B-17 conducted by the European Organization for Research and Treatment of Cancer (EORTC) in 1986-1996 with a 15-year follow-up, the results of the study showed a reduction in local recurrence of invasive and non-invasive breast cancer (DCIS) in the post-BCS radiotherapy group, with no statistical differences found for OS and breast cancer-specific survival, and the same results were obtained for independent The same results were obtained after stratification of risk factors. ECOG E5194: Can breast cancer including local excision (LE) without radiotherapy be applied to low/intermediate grade DCIS? The Eastern Collaborative Oncology Group (ECOG) included 671 patients from 1997-2002 to study recurrence of DCIS without radiotherapy on the affected side after LE. The results of the study showed that the IBTR rate after 5 years of LE was within acceptable limits for low-risk DCIS, whereas LE alone was not feasible for patients with high-grade DCIS, so genetic testing for DCIS was proposed to guide the surgical approach. Sentinel lymph node biopsy: Based on the NSABP-B04 study, resection of benign axillary lymph nodes did not provide clinical benefit but rather increased the incidence of adverse events (lymphedema, pain, etc.), so Giuliano's 1994 clinical study of 114 patients proposed sentinel lymph node biopsy (SLND) in patients with early-stage breast cancer as a staging method for negative axillary lymph nodes. The method has attracted a lot of attention. ACOSOG Z0010: The American College of Surgeons (ACOSOG) studied the relationship between sentinel lymph node status and bone marrow micrometastasis in 1999-2003 and pointed out that SLND was feasible for early stage breast cancer, setting the precedent for clinical use of SLND technique. NSABP B-32: SLND can replace axillary lymph node dissection (ALND). In order to investigate whether SLND has the same survival benefit as ALND, B-32 studied SLND + ALND and ALND after SLND (+) from 1999-2004, and pointed out that for patients with axillary lymph nodes (-), if SLN (-) is not necessary, ALND is feasible. This approach is feasible. ACOSOG Z0011: Based on the fact that axillary lymph nodes may not require ALND when there are <3 anterior lymph node metastases, in 1999, ACOSOG conducted the Z0011 study, which included patients with clinical axillary lymph nodes (-) at T1 and T2 stages, but <3 anterior lymph node metastases, and compared the differences in OS, DFS, and local/regional recurrence between SLND and ALND. , the results showed no statistical difference between the two groups, and therefore ALND may not be necessary for certain patients with limited sentinel lymph node metastases. IBCSG 23-01: To investigate whether SLND is superior to ALND in terms of DFS, OS, and recurrence rates for patients with micro-metastases (≤2 mm) in axillary sentinel lymph nodes and ≤125 px primary tumor, the International Breast Cancer Study Group (IBCSG) The International Breast Cancer Study Group (IBCSG) enrolled 934 patients between 2001-2010 and found no statistical difference, indicating that ALND could be avoided for patients with small primary tumors or micro-metastases in the anterior lymph nodes. ACOSOG Z1071: To investigate whether SLND could be performed instead of ALND in patients after downstaging by neoadjuvant chemotherapy, ACOSOG enrolled T0-T4, N1-N2, M0 The study found that in patients with neoadjuvant chemotherapy, tumor biology influenced the rate of breast-conserving surgery and PCR, and patients with TNBC and HER2 types were more likely to undergo less invasive surgery after neoadjuvant chemotherapy.