title: Tumor volume is a better predictor of post-operative wound complications compared to tumor size in soft tissue sarcomas of the proximal lower extremity.
abstract: BACKGROUND
  Wide local excision with or without radiation therapy (RT) and chemotherapy is widely accepted as appropriate management for soft tissue sarcomas (STS) of the extremity. Although survival and local control rates are comparable to amputation, post-operative wound complications (WC) following limb salvage can result in significant morbidity for the patient. Certain risk factors such as location, pre-operative RT, and age have been shown to increase the risk of WCs. Somewhat surprisingly, size has not consistently been shown to impact WC rates. The goal of this study is to assess whether tumor volume, as opposed to the traditional measurement of the largest dimension in one plane, correlates with the development of post-operative WCs.
  
  
  METHODS
  Between 2000 and 2013, 81 patients with STS of the proximal lower extremity, buttock and pelvis were retrospectively identified from our prospective database. We reviewed the impact of patient, tumor, and treatment variables on postoperative WC. Predictors for WC were evaluated using the Fisher exact test for univariate analysis and logistic regression for multivariate analysis. Tumor volume was determined using the medical image merge (MIM) (®) software program (version 6.5.4, MIM Software, Cleveland, OH). Tumor size (diameter) was determined the historical way of measuring the widest dimension on the sagittal, coronal, and axial planes from the MRI scan at midplane.
  
  
  RESULTS
  The overall WC rate within 6 months of tumor resection was 32 %. WC were more likely to occur with larger tumor volumes (p = 0.015), although not with tumor diameters ≥10 cm (p = 0.55). Neither volume of subcutaneous fat (p = 0.34) or depth of the subcutaneous fat layer (p = 0.82) significantly impacted WC rates. Tumor proximity to skin surface also did not significantly impact WC risk (p = 0.73).
  
  
  CONCLUSIONS
  Increase in tumor volume led to a higher risk of post-operative WCs. Assessing tumor volume may allow clinicians to better counsel patients on their risk of post-operative WCs. Tumor volume, as opposed to size alone, should be considered in future sarcoma outcome studies.
authors.affiliation: Department of Orthopaedic Surgery, Medical College of Wisconsin, 9200 West Wisconsin Ave, Milwaukee, WI 53226 USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Ziegele
authors.affiliation: Department of Orthopaedic Surgery, Medical College of Wisconsin, 9200 West Wisconsin Ave, Milwaukee, WI 53226 USA.
authors.forename: David M
authors.initials: DM
authors.lastname: King
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, 9200 West Wisconsin Ave, Milwaukee, WI 53226 USA.
authors.forename: Manpreet
authors.initials: M
authors.lastname: Bedi