A Comparative Study of Delayed Endoscopic DTI and Latissimus Dorsi ±Impalnt Reconstruction Post-Mastectomy

This study is a multicenter, open, prospective cohort study. Inclusion criteria: (1) Female patients aged 18 - 70 years (inclusive) who have undergone simple mastectomy for breast cancer; (2) Patients with good local flap viability and laxity one year after total mastectomy or six months after completion of radiotherapy; (3) Patients who are able and willing to sign the informed consent form. Exclusion criteria: (1) Recurrence detected on follow-up (based on clinical, imaging, or pathological findings), including local/regional recurrence or uncontrollable distant metastasis; (2) Patients who had the pectoralis major muscle resected during the initial mastectomy; (3) History of thoracic or back surgery with suspected damage to the thoracodorsal vessels; (4) Poor general condition and inability to tolerate surgery; (5) Presence of severe comorbidities, such as uncontrolled diabetes, severe bone marrow suppression after breast cancer treatment, compromised immune function, or a history of long-term smoking; (6) Participation in other clinical studies that may interfere with this trial. Prior to group allocation, investigators at each research center will first stratify the subjects by radiotherapy. The subjects will be divided into two groups based on whether they have received radiotherapy, with the sample size ratio of the radiotherapy group to the non-radiotherapy group being 1:2. Subsequently, the subjects will be assigned to the two-stage endoscopic immediate prosthesis breast reconstruction group (with a proportion of "3") and the latissimus dorsi±prosthesis breast reconstruction group (with a proportion of "1"). The target sample size is 268 participants, comprising 89 in the radiotherapy group (67 in the two-stage endoscopic immediate prosthesis breast reconstruction group, 22 in the latissimus dorsi±prosthesis breast reconstruction group) and 179 in the non-radiotherapy group (134 in the two-stage endoscopic immediate prosthesis breast reconstruction group, 45 in the latissimus dorsi±prosthesis breast reconstruction group). Collecting data includes encompassing demographics (e.g., age, BMI, breast ptosis), medical history (e.g., comorbidities, prior surgeries, family cancer history), oncological profiles (e.g., tumor type, size, location, stage, immunohistochemistry, nodal status, neoadjuvant/adjuvant therapies), and surgical details (e.g., procedure type, operative time, intraoperative blood loss, margin status, gland resection weight, implant size, drainage placement) from preoperatively to postoperatively. Postoperative follow-ups at 1 month, 6 months, 1 year will document complications, cosmesis (BREAST-Q, SCAR-Q, QLQ-BR45, Harris and Ueda assessments). Complications are recorded per patient, with events classified as major, minor, or any using the Clavien-Dindo grading system (Grades I-II: minor; III-IV: major). BREAST-Q/SCAR-Q/QLQ-BR45 questionnaires will be completed preoperatively and at 6 months/12 months postoperatively, alongside Harris and Ueda assessments and standardized breast photography (anteroposterior, lateral, oblique views). An interim analysis will occur 1 year after study initiation and 1 month post-enrollment completion. Final analysis follows 1-year postoperative follow-up for all participants. Categorical variables will be analyzed using chi-square or Fisher's exact tests; continuous variables via t-tests, ANOVA, or non-parametric alternatives (Mann-Whitney/Kruskal-Wallis) as appropriate. Survival outcomes will employ Kaplan-Meier curves with log-rank testing.