Modified surgical excision, also known as modified radical surgery, in the case of breast cancer, refers to an effective treatment that does not require the removal of the breast and pectoralis major and minor muscles, and maintains the original appearance of the breasts at the same time. Modified radical surgery for breast cancer can be broadly categorized into two types, one is to remove the pectoralis minor muscle and preserve the pectoralis major muscle; the other is to preserve both the pectoralis major and pectoralis minor muscles. 1. Excision of pectoralis minor muscle and preservation of pectoralis major muscle: the scope of lymph node dissection is similar to that of radical surgery. 2. Preservation of both pectoralis major and minor muscles: this type of surgery is not easy to remove lymph nodes in the supra-axillary group. Through observing a large number of cases, it is found that there is no statistically significant difference in the postoperative survival rate between patients with stage I and stage II breast cancer who have undergone modified radical surgery or radical surgery. Because modified radical surgery preserves the pectoral muscles and has aesthetic appearance after surgery, it is a more commonly used surgical method nowadays.