The early stage of breast cancer can produce hematogenous dissemination, indicating that breast cancer should be considered as a systemic disease [1]. Studies have confirmed that extensive local excision combined with radiotherapy has similar long-term outcomes compared to radical and modified radical mastectomy . Breast-conserving surgery has become the most commonly used surgical procedure for stage I-II breast cancer in developed countries such as Europe and the United States. In recent years, breast-conserving surgery has been reported in some cases of late clinical stage breast cancer after neoadjuvant chemotherapy. 1. General data: All 93 cases of breast cancer were from patients treated in our hospital from March 1990 to March 2010. All clinical data were reliably and well documented, and the stage of tumor was determined according to AJCC staging, and all had reliable pathological diagnosis and follow-up data. All patients were single lesions with tumor margins >2 cm from the nipple and had a strong desire for breast conservation. 93 breast cancer cases were 26-71 years old, average 41.3 years old; tumor primary foci were 1M-5.5M in diameter, average 3.1M. pathological types included 63 cases of invasive ductal carcinoma, 12 cases of simple carcinoma, 7 cases of adenocarcinoma and 11 cases of other types; clinical stages: 41 cases of stage I (44.1 The clinical stage: 41 cases (44.1%) were stage I, 51 cases (54.8%) were stage II, and 1 case (1.1%) was stage III. 2. Treatment method: The surgery was performed by enlarging the tumor and removing the tumor together with the surrounding normal tissues of about 2 cm, and then deciding whether to enlarge the tumor again according to the results of rapid pathological examination of the cut edge, and clearing the lymph node tissue of the ipsilateral axilla at the same time. In this group, 67 cases underwent breast-conserving surgery directly, 26 cases underwent breast-conserving surgery after preoperative neoadjuvant chemotherapy, and 3 of them underwent breast-conserving surgery together with latissimus dorsi muscle flap grafting. All cases had negative margins, 73 patients had no metastasis in axillary lymph nodes and 20 patients had metastasis in 1-3 lymph nodes. 93 patients received whole breast radiotherapy with a total of 46-50 GY. 20 cases (before 1993) were treated with high dose rate iridium 192 brachytherapy (insertional radiotherapy) in the tumor bed with a supplemental volume of 12-15 GY; 56 cases received 3D conformal radiotherapy and 17 cases received intensity-modulated radiotherapy. The schedule of radiotherapy was as follows: 35 patients received radiotherapy after incision healing at 2 weeks after surgery, and the rest received radiotherapy after 1-3 courses of chemotherapy. All patients completed 6 courses of chemotherapy with CMF, CAF or TA regimens, 67 had 6 courses of postoperative chemotherapy, and 26 had 6 courses of preoperative and postoperative chemotherapy together; patients with positive ER and/or PR receptors by immunohistochemistry were treated with endocrine therapy (triamcinolone acetonide, anastrozole or goserelin + anastrozole) for 5 years. 3, Statistical methods: Survival rate was analyzed by Kaplan-Meier analysis, and the difference in survival curves was tested by Log-rank test. p<0.05 was considered as a significant difference, and statistical processing was done by SPSS13.0 statistical software. The follow-up rate was 94.6% (88/93). 93 patients had 3 cases of local recurrence (3.2%) and 5 cases of death, including 1 case of lung metastasis, 1 case of liver metastasis, 2 cases of bone metastasis, 1 case of liver, bone and other systemic multiple metastases; 5 cases were lost, and the overall survival rate was 89.2%. The overall survival rate was 89.2%, and 80 cases (86.0%) were tumor-free. The 5-year survival rate was 92.3%, and the tumor-free survival rate was 89.2%; the 10-year survival rate was 89.3%, and the tumor-free survival rate was 85.7%. According to the evaluation of the cosmetic effect of preserved breast by Bao-Ning Zhang et al [2], the patients in this group were excellent except for one average and eight poor cases, and the satisfaction rate was 90.3% (84/93). Univariate analysis of prognostic factors was performed in this group of cases, and no significant effects of age, tumor size, clinical stage and axillary lymph node metastasis on tumor prognosis were found. Discussion 1. Size of primary tumor in breast-conserving treatment: tumor size is not an absolute contraindication to breast-conserving treatment, and the maximum tumor diameter ≤3 cm is an indication for breast-conserving treatment [6], and the maximum tumor diameter 3-5 cm depends on the tumor breast ratio. In our data, 67 cases with small tumor diameters directly performed breast-conserving surgery; 26 cases with larger tumor diameters achieved clinical PR after preoperative neoadjuvant chemotherapy, and after performing breast-conserving surgery; all achieved satisfactory cosmetic results. In recent years, some breast cancers with late clinical stage were treated with breast-conserving surgery after neoadjuvant chemotherapy and the local recurrence rate did not increase significantly. Therefore, the authors believe that in addition to early stage breast cancer, stage II breast cancer with large primary tumor or even late stage breast cancer can be considered for breast-conserving treatment after neoadjuvant chemotherapy to reduce the lesion, and the recent efficacy is good, and all of them can achieve satisfactory cosmetic effect. 2. Breast-conserving surgery: Breast-conserving surgery mainly includes extended primary cancer resection, mastectomy and 1/4 quadrant resection, all of which require negative margins to reduce the local recurrence rate. In our study, the local recurrence rate was 1.3%, 4.0%, and 5.2% for breast cancer patients with negative margins, tight margins, and positive margins, respectively, when they received radiotherapy; and Gatek et al [8] concluded that a negative margin is a very important factor in preventing local recurrence in breast-conserving treatment of breast cancer. Therefore, the authors suggested that breast-conserving surgery should be performed on the premise of ensuring negative margins, and the amount of breast tissue removed should be reduced by extended primary cancer resection in order to maintain the postoperative breast shape; and for patients with large breast tumor ratio, autologous tissue transplantation such as latissimus dorsi muscle flap transplantation can be performed at the same time of breast-conserving surgery in order to maintain the postoperative breast shape. Radiotherapy in breast-conserving treatment: all patients in this group received whole-breast radiotherapy after breast-conserving surgery. 8 patients with insertion radiotherapy had longer healing time at the insertion pinhole and more obvious fibrosis and contracture of breast tissue, which affected the cosmetic effect; some patients with three-dimensional conformal radiotherapy had more obvious radiation dermatitis and radiation pneumonia; while some patients with intensity-modulated radiotherapy only had mild radiation dermatitis and radiation pneumonia. Dragun et al [9] found that the 10-year overall survival rates of breast-conserving surgery + radiotherapy and breast-conserving surgery alone were 79.7% and 67.6%, respectively, and the differences were statistically significant. Bao-Ning Zhang et al [2] concluded that radiotherapy is mandatory after breast-conserving surgery, and radiotherapy is usually followed by chemotherapy; a regimen of chemotherapy followed by radiotherapy or chemotherapy followed by radiotherapy followed by chemotherapy can be used for those with high-risk factors such as age ≤ 35 years, lymph node metastases ≥ 4, and vascular tumor emboli. Therefore, the authors believe that whole-breast radiotherapy must be performed after breast-conserving surgery; the schedule of radiotherapy can be based on the size of the risk of local recurrence and distant metastasis, and chemotherapy + radiotherapy, chemotherapy + radiotherapy + chemotherapy, respectively; radiotherapy should preferably be intensity-modulated radiotherapy to maintain a good cosmetic effect and reduce the complications of radiotherapy. 4.Long-term efficacy of breast-conserving treatment: A prospective multicenter clinical study on breast-conserving treatment for breast cancer showed that the local recurrence rate of breast-conserving treatment group was 1%, the distant metastasis rate was 1.3%, and the mortality rate was 0.1%; the local recurrence rate of total mastectomy group was 0.5%, the distant metastasis rate was 1.4%, and the mortality rate was 0.1%; the differences of local recurrence rate, distant metastasis rate and mortality rate between the two groups after surgery were not statistically significant. The difference in local recurrence rate, distant metastasis rate and mortality rate between the two groups was not statistically significant, and breast-conserving treatment had no negative impact on the survival rate and recurrence rate of early-stage breast cancer patients and improved their quality of life. Cao Feng et al [10] used Meta-analysis system to evaluate the long-term efficacy of breast-conserving treatment versus total mastectomy for early invasive breast cancer, and concluded that for early invasive breast cancer, the long-term prognosis of patients treated with breast-conserving treatment was comparable to that of patients treated with total mastectomy, but the postoperative local recurrence rate was significantly higher in breast-conserving patients. In our data, the local recurrence rate and distant metastasis rate were lower, and the overall survival rate was higher; and the univariate analysis of prognostic factors in this group of cases did not reveal any significant influence of age, tumor size, clinical stage and axillary lymph node metastasis on tumor prognosis. This may be related to the small number of cases in this group and the fact that most of them were stage I-II breast cancers with small primary tumors. In the early stage of breast-conserving treatment, we selected cases with primary tumors ≤3 cm in diameter; only in recent years have we started to perform breast-conserving treatment for breast cancer with larger primary tumors and significantly smaller lesions after preoperative neoadjuvant chemotherapy, and the follow-up time for these patients is shorter. Therefore, the long-term efficacy of breast-conserving treatment for breast cancer with large primary tumors that have been reduced by preoperative neoadjuvant chemotherapy needs to be further followed up.