The application of mixed reality to sentinel lymph node biopsy in breast cancer Running title: Application of mixed reality in breast cancer

Abstract Background This study aimed to explore the value of mixed reality (MR) in sentinel lymph node biopsy (SLNB) in patients with breast cancer. Methods A total of 300 patients with breast cancer who underwent SLNB in the Department of Breast Surgery of The Second Affiliated Hospital between August 2018 to March 2019 were enrolled. They were randomly divided into two groups using a random number table. In group A, only dye (an injection of methylene blue) was used to detect sentinel lymph nodes, while in group B MR was used for positioning in addition to dye. Results During surgery, the detection time in group B was significantly shorter than in group A (3.62 ± 1.20 vs.7.87 ± 1.86; p < 0.001). At the one- and six-month post-surgery follow-ups, the incidences of pain and numbness in group B were lower than in group A (2.70% vs. 8.28%, p = 0.036; 0.68% vs. 3.45%, p = 0.094, respectively), the incidence of upper limb dysfunction in group B was lower than that of group A (2.03% vs. 8.97%, p = 0.009; 0% vs. 2.07%, p = 0.120, respectively), and the patient satisfaction score of group B was higher than that of group A (4.04 ± 0.91 vs. 3.32 ± 0.94, p < 0.001). Conclusion MR can construct a three-dimensional visualization model for use in surgery. The application of this technology to SLNB in patients with breast cancer can significantly reduce the detection time and the occurrence of complications and improve patient satisfaction.