What is Optimal Post-operative Prophylactic Therapy in Irradiated Breasts Undergoing Repeat Surgery

Background: The 10-year local recurrence rate for breast cancer following breast conserving surgery (BCS) and radiation therapy (RT) is estimated around 19% for which the standard of care is completion mastectomy. This represents a growing population of patients with prior irradiation undergoing repeat oncologic surgery. Patients undergoing surgery after RT have been shown to be at higher risk for wound complications such as surgical site infection (SSI), dehiscence, and skin necrosis. The average rate of SSI following major breast surgery is estimated at 5%, whereas it has been reported over 30% in irradiated patients. However, the data remains sparse dedicated to mitigating early wound complications in this patient population with guidelines or recommendations that exist for prophylactic measures. A retrospectively review analyzed SSI rate in patients undergoing mastectomy without reconstruction and found a statistically significant reduction in SSI rate with post-operative antibiotics in the subset of patients with previous RT (30.8% to 3.6%). In another study of a prospectively followed cohort of high-risk patients undergoing breast cancer surgery, a subset of whom had previous RT, these patients were found to have a significant reduction from 45% to 4% for all wound complications (no reported SSI) with closed incision negative pressure wound therapy (ciNPT) and post-operative antibiotics. Therefore, the investigators hypothesize that patients with prior BCS and RT undergoing repeat oncologic breast surgery would benefit from post-operative prophylactic therapy to reduce early wound complications. Retrospective analyses and prospective cohort studies have demonstrated potential benefit; however, a high quality RCT is warranted to analyze our research question. Study Design: The investigator's primary objective will be to evaluate the effect of a 7-day course of TMP-SMX DS and 7-day application of ciNPT dressing (PICO) on the rate of early wound complications in this patient population. This study will be designed as an unblinded block randomized controlled trial with three arms: 1) standard of care 2) post-operative antibiotics 3) ciNPT. Participants will be recruited by surgeons at the Meadowlark and Sturgeon surgical clinics. Data will be collected via paper forms or Connect Care at 1-2 week and 4-6 week post-operative visits. The primary outcome measure will be wound complications (SSI, dehiscence, skin necrosis). Secondary outcomes will include adverse effects of antibiotics or ciNPT therapy, and other post-operative complications (extended antibiotic therapy, re-operation, admission to hospital). Impact: The investigators hope the results of this trial will demonstrate benefit of prophylactic antibiotics and/or ciNPT to decrease wound complications in this patient population. This will have the potential to create recommendations for a post-operative prophylactic regimen to inform future guidelines and practice in oncologic breast surgery.