(P 353) PREDICTING WOUND COMPLICATIONS FOLLOWING SOFT-TISSUE SARCOMA RESECTION AMONG PATIENTS WHO RECEIVED PRE-OPERATIVE RADIATION

Objective: Radiation therapy (XRT) is often used in combination with surgical resection in the treatment of soft-tissue sarcomas (STS). Compared to post-operative radiation therapy, pre-operative XRT enables smaller radiation doses and treatment fields, reducing time and cost of treatment and risk for chronic radiation toxicity. However, pre-operative RT is also associated with higher rates of wound complications following surgical resection. Other clinical factors such as tumor location, size, distance from skin surface, and comorbidities such as diabetes, tobacco use, vascular disease, and obesity have also been shown to be associated with wound complications. A trial conducted by Kalbasi et al. assessing a 5-day neoadjuvant RT regimen for STS uncovered a signature of 19 germline SNPs that were predictive of wound complications (Kalbasi et al., Clinical Cancer Research, 2020). Our objective is to perform a similar analysis of plasma samples collected at the time of surgical resection from patients who received pre-op radiation for STS to determine whether levels of circulating tissue markers are predictive of wound complications.

Methods: An inventory summary of our institution’s Musculoskeletal Oncology Tumor Registry and Tissue Bank (MOTOR) was performed to identify soft-tissue sarcoma patients who received pre-operative radiotherapy. 60 plasma samples were available from pathology. Of these, 48 had data available regarding preoperative radiotherapy details, and 23 received radiotherapy with pre-operative intent (RT finishing < 12 weeks prior to surgery). Patients’ medical charts were reviewed to identify wound complications, tumor location, tumor size, comorbidities, and radiation plan details. Wound complications were defined as wound care requiring a secondary operation, hospital readmission, invasive procedure, deep wound packing, prolonged dressing change, or revision of skin graft. ELISA will be performed on each plasma sample to determine circulating levels of TGF-b, VEGF, IL-1, IL-6, IL-8, TNF-a, IFN-y, EGF, FGF, PDGF, NO, MMP-1, MMP-2, MMP-12, MMP-13, and TIMP, factors in the wound healing process that have been shown in a prior study by Haubner et al. to be affected by radiation therapy (Haubner et al., Radiation Oncology, 2012). Descriptive statistics and two-sample t-tests were used to compare clinical characteristics between the wound complication and no-wound complication groups. Multiple logistic regression will be used to determine the effect of each tissue marker on wound healing while accounting for confounding variables and comorbidities. This project was supported in part by the Hillman Fellows for Innovative Cancer Research Program funded by the Henry L. Hillman Foundation.

Results: Of the 23 included patients who had pre-operative XRT, 8 experienced wound complications, all of whom required at least one additional operation for wound care. Differences in the type of soft tissue sarcoma, tumor location, diabetes diagnosis, tobacco use, time between end of RT and surgery, and RT dose between patients who did and did not experience wound complications are shown in Table 1. Two-sample t-test confirmed that the proportion of tumors that were located in patients’ legs in the wound complication group (8/8) was significantly greater than in the no wound complication group (8/15), with a p-value of 0.01. The difference in mean time between the end of RT and surgery between the two groups was not statistically significant (52.27 days vs. 44.13 days, p = 0.067). Protein analysis is planned on plasma samples, and these data will enable us to analyze if the previously mentioned tissue markers are associated with wound complications while accounting for factors known to be associated with wound complications through multiple logistic regression.

Conclusion: Results from this clinical database confirm the known relationship that lower extremity soft tissue sarcoma excisions are associated with higher rates of wound complications. The results from the plasma analysis will help predict future patients’ risk for wound complications by analyzing protein levels in patients’ pre-operative plasma samples. Furthermore, the results will serve as exploratory analysis for a planned prospective trial examining the effect of a bacterial decolonization regimen and intraoperative indocyanine green angiography on the incidence of wound complications in patients who undergo pre-operative radiation therapy for soft tissue sarcoma.