Breast cancer patients often receive systemic drugs as the initial curative treatment of their disease. The initial systemic therapy leads to a variable degree of tumor shrinkage. At present, there is no evidence-based consensus among breast surgeons on the optimal extent of resection after considerable tumor shrinkage and whether resection margin should be designed according to the tumor extent before treatment or the extent after treatment. This trial will help determine the optimal extent of resection in tumors that exhibits a significant change in volume after primary systemic therapy.
Inclusion Criteria: * Biopsy-proven diagnosis of invasive adenocarcinoma of the breast. * Tumor stage T 1-4b * Nodal stage N 0-2 * ASA (American Society of Anesthesiologists) class I-II Exclusion Criteria: * Patients opting for mastectomy. * Patients advised for mastectomy by the treating physician. * Patients opting for primary surgical treatment. * Patients advised for primary surgical treatment by the treating physician. * Metastatic patients. * Multifocal tumors. * Lobular neoplasia. * Current pregnancy or pregnancy less than 6 months from the enrollment date. * Active second cancer.