This study investigated the clinical effect of metformin on breast cancer patients with preexisting type 2 diabetes mellitus (T2DM). We analyzed 177 patients with T2DM who underwent breast cancer surgery and assessed tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs) in patients who underwent tumor resection with or without metformin treatment using multiplex immunohistochemistry (IHC). Patients who received metformin either pre- or postoperatively exhibited reduced distant organ recurrence and improved postoperative recurrence-free survival compared to those of patients who did not. Additionally, in a subgroup of 40 patients receiving preoperative systemic therapy, metformin treatment was associated with increased rates of pathological complete response.IHC analysis revealed significantly lower levels of cluster of differentiation (CD) 68(+) CD163(+) M2-type TAMs (p < 0.01) but higher CD3(+) and CD8(+) TIL densities in the metformin-treated group compared with the same parameters in those without metformin treatment, with a significant difference in the CD8(+)/CD3(+) TIL ratio (p < 0.01). Despite the constraints posed by our small sample size, our findings suggest a potential role for metformin in modulating the immunological microenvironment, which may contribute to improved outcomes in diabetes patients with breast cancer.

A live animal training program is offered to medical students seeking more advanced surgical education. This program requires active participation in all aspects, from planning to implementation.　The program provides medical students with a valuable opportunity to develop their interest in surgical care and to acquire advanced surgical techniques through a step-by-step approach. Additionally, they have the chance to develop various types of non-technical skills by assuming different roles within a team. Instructors offer support for their learning.　Peer learning allows medical students to learn from and discuss with each other, enabling them to acquire a broad range of knowledge and skills. Simultaneously, students are expected to understand the importance of a team approach by participating in this program from the perspectives of various medical professions. Moreover, the program contributes to the formation of their professional identity.