The introduction of the Mammotome (MMT) system has made the treatment of breast lumps minimally invasive, accurate, efficient, safe and cosmetically desirable. The MMT has thus become the world’s most advanced device for minimally invasive breast biopsy and removal of smaller benign lesions. According to its conventional performance, MMT surgery for the removal of breast lesions less than 2.5 cm in diameter has long been unsurprising. However, MMT surgery is relatively difficult to remove larger masses over 3 cm. In our hospital, we have performed more than 5000 cases of MMT surgery, among which, 200 cases of minimally invasive rotational resection of large benign breast masses with diameters of 3cm to 6cm were performed by using MMT manual assistance combined with ultrasound-guided fan advancement rotational resection, and the efficacy was compared with those of small lesions with good results. Fibroadenoma and hyperplasia-like changes in the breast are common in young women, and many of them have large masses. According to the traditional open surgery, whether the mass is excised or segmental excision, there are painful surgical incisions and suture changes, especially for young and unmarried women who have not had children, which can cause physical and psychological damage. As people’s living standards continue to improve and their awareness of beauty grows stronger, there is an urgent need for a surgical method that can remove the lesion without damaging the aesthetics. The McMurdo Minimally Invasive Rotational Excision System was invented in 1994, and its introduction has brought the ideal results of minimally invasive, accurate, efficient, safe and cosmetic treatment of breast lumps. This has made the McMurdo minimally invasive rotational excision procedure the most advanced method in the world for minimally invasive breast biopsy and the ideal excision of smaller benign lesions. According to its conventional performance, it can completely remove smaller breast lesions under 2.5cm, and the minimally invasive McMurdo spinotomy procedure to remove breast lesions under 2.5cm in diameter has been commonly performed in large and medium-sized hospitals in China. The U.S. Food and Drug Administration (FDA) has also approved the use of minimally invasive McMortem for the complete removal of small breast tumors. However, it is difficult to remove larger masses over 3 cm. In clinical practice, more and more patients with large benign breast masses are requesting to undergo minimally invasive McMurdo spinotomy. In practice, I have learned that by moving the direction and depth of the rotary cutter, the scope of excised tissue can be indirectly expanded beyond the 2.5 cm limit. The cylindrical shape of the MMT rotary knife allows for 360° rotation and anterior and posterior adjustment of its depth in the tissue, which makes resection of large masses theoretically feasible. The author extended the conventional performance of the MMT by using a hand-assisted combination of ultrasound guidance to perform a transverse sector combined with a longitudinal advancement method for benign breast masses of 3 cm to 6 cm in diameter, i.e., to extend the resection range of the rotary knife in both left and right and anterior and posterior dimensions, making it possible to resect masses of 3 cm to 6 cm in diameter with a 2.5 cm diameter rotary cutter head. Before the procedure was applied to the clinic, the author made his own animal model (squash placed inside pork) for experimental surgery and achieved dozens of successful cases before putting it into clinical implementation. The author summarized this method as the McMurdo fan advancement method. In the test group, 200 mammary lesions were excised by the McMurdo fan advancement method of spinotomy, with an average of 30 (15-80) spinotomies and a time of 20 min, without any failure. 10 cases had mild subcutaneous petechial hemorrhage (5%), which was absorbed by itself after hot compressing; 4 cases had local hematoma (2%) caused by compression and loosening, which was cured by puncture and aspiration and re-pressing and dressing. There were no other complications such as wound infection. There were 31 cases of intraoperative bleeding, with bleeding volume ranging from 10 to 30 ml, averaging 20 ml. The control group underwent the usual McMurray protocol. The incision healing time was 3 d in both groups, and the postoperative skin scar was 3 mm. although the test group had slightly more operative time and bleeding than the control group due to the large tumor, there was no statistically significant difference in the incidence of complications such as intraoperative bleeding, skin ecchymosis, and postoperative hematoma by chi-square test (P>0.05). The results of this study showed that the minimally invasive spinotomy with the McMurdo fan advancement method for larger breast masses was identical to the McMurdo minimally invasive spinotomy for small masses in terms of hospital stay and surgical scar appearance (incision healing time was 3 d for both, and postoperative skin scar was 3 mm for both). The test group had slightly more operative time and bleeding than the control group because of the large tumor, but their results were comparable in terms of complication rates such as intraoperative bleeding, skin ecchymosis, and postoperative hematoma. The chi-square test performed for each showed that the P values were >0.05, indicating that there was no significant difference in the efficacy of the two. It is suggested that minimally invasive McMurdo fan advancement spinotomy for larger breast masses is as safe and feasible as McMurdo minimally invasive spinotomy for small masses.