LAUSR

We commend Dr. Villano and colleagues for undertaking this important appraisal of modern variabilities in therapeutic strategies between lowand high-volume retroperitoneal sarcoma (RPS) centers. The authors used the National Cancer Database (NCDB) to demonstrate a trend toward increased use of preoperative radiotherapy (RT) and multi-visceral resections in centers performing a low volume of primary RPS resections, bringing them closer to practicing patterns in place at high-volume centers. Whether the trend toward adoption of these practices translated into better outcomes was not investigated. Thus, whether the observed trend has led to a consistent improvement in the quality of care that RPS patients receive across the United States remains uncertain. One challenge is the difficulty of objectively identifying why patients treated at high-volume RPS centers have better results than those treated at low-volume RPS centers. We assume that team characteristics, experience, and expertise in patient selection, local therapies, and multidisciplinary strategies play critical roles, as do institutional characteristics such as ability to rescue after a complication. Nonetheless, factors such as size of the country, insurance policies, and patient preference have resulted in RPS care remaining balkanized rather than regionalized although data supporting the need to regionalize RPS care are available and in fact compelling. The high proportion of patients in the United States who do not have their primary RPS resected at a high-volume center is worrisome. Previous studies have demonstrated that higher case volume is associated with better survival. In the current study, only 9.3% of the patients undergoing surgery for primary RPS had their surgery at a high-volume hospital (HVH) between 2004 and 2017, similar to the 9.8% rate reported previously by Keung et al. in a NCDB study spanning an overlapping period (1998–2011). However, a threshold value for case volume has not been clearly identified to date. In the current study, the definition of HVH was based on a threshold of more than 10 cases per year (the same as in the prior Keung et al. study). A previous study performed by the same authors had identified a target of 13 cases per year. However, these numbers should be viewed with caution because very few centers contributing to the NCDB manage more than 10 cases per year. In addition, the mean number of cases treated at HVHs was 30 per year in the prior study and 18 per year in this new study. The reported proportional improvement in overall survival (OS) by the increased number of cases per year, which plateaued after 13 cases per year in the first study, may well be related to centers that treat a significantly higher number of cases. Therefore, a real data-driven threshold remains uncertain. In Europe, a consensus document proposed the performance of 30 to 40 cases per year as one of the requirements for an expert sarcoma surgeon and 100 new cases per year as the threshold for a sarcoma center, including nonsurgical Society of Surgical Oncology 2021