A little more than 5% of patients undergoing breast surgery developed infections at the incision site, resulting in more than $4,000 extra hospital-related costs per patient, according to research reported in the January Archives of Surgery. The research headed by Dr. Margaret A. Olsen of the Washington University School of Medicine, St. Louis showed that 50 of the 949 women studied, who had undergone mastectomy or breast reconstruction, developed surgical site infections within a year.