Breast cancer, the most prevalent malignancy among women globally, is increasing in incidence. While non-metastatic breast cancer requires surgery, determining the optimal extent of resection remains challenging. Inadequate resection margins necessitate reoperation, leading to increased psychological stress, costs, and potentially compromised cosmetic outcomes and prognosis.

Accurate preoperative assessment of resection extent is crucial and involves various factors, including imaging studies, physical examinations, tumor molecular subtypes, and intraductal carcinoma components. This prospective observational study aims to identify and integrate multiple predictive factors to enhance surgical planning and minimize reoperation rates in breast cancer patients.

Breast cancer is the most prevalent malignancy among women globally, leading to surgical interventions for non-metastatic cases. While breast cancer generally has a favorable prognosis, achieving negative resection margins at initial surgery is crucial for optimal outcomes. The challenge associated with accurately predicting the extent of resection preoperatively, as failure to secure clear margins may necessitate further resection or total mastectomy, resulting in increased psychological stress, higher healthcare costs, compromised cosmetic results, and potential negative impacts on long-term prognosis and quality of life. Many factors contribute to predicting the optimal resection extent, including imaging studies, physical examination findings, tumor molecular subtypes, presence and extent of intraductal carcinoma components, etc. Despite the availability of these predictive factors, their integration and practical application in clinical decision-making remain challenging. This prospective observational study aims to address this gap by analyzing the interplay of these factors in real-world clinical settings, with the primary objective of deriving an integrated predictive model to guide surgeons in determining the optimal extent of resection preoperatively.

Inclusion Criteria:

Adult patients (≥ 19 years old) diagnosed with breast cancer (invasive and in situ).

Patients scheduled for surgical resection of the tumor Availability of both preoperative tumor size assessments and pathologic measurements post-surgery

Exclusion Criteria:

Patients with recurrent breast cancer Inflammatory breast cancer Patients who did not undergo surgery Patients whose preoperative tumor size data is not available or deficient for analyzing

The study population will be enrolled from patients at Incheon Saint Mary's Hospital, a 1000-bed tertiary academic medical center located in Incheon, South Korea.