Comparing Multivisceral Resection with Tumor-only Resection of Liposarcoma Using the Win Ratio.

BACKGROUND: Multivisceral resection of retroperitoneal liposarcoma (LPS) is associated with increased morbidity and may not confer a survival benefit compared with tumor-only (TO) resection. We compared both approaches using a novel statistical method called the "win ratio" (WR).

METHODS: Patients who underwent resection of LPS from 2004 to 2015 were identified from the National Cancer Database. Multivisceral resection was defined as removal of the primary site in addition to other organs. The WR was calculated based on a hierarchy of postoperative outcomes: 30-day and 90-day mortality, long-term survival, and severe complication.

RESULTS: Among 958 patients (multivisceral 634, TO 324) who underwent resection, the median age was 63 years (interquartile range [IQR] 54-71) with a median follow-up of 51 months (IQR 30-86). There was no difference in the WR among patients who underwent TO versus multivisceral resection in the matched cohort (WR 0.82, 95% confidence interval [CI] 0.61-1.10). In patients aged 72-90 years, those who underwent multivisceral resection had 36% lower odds of winning compared with patients undergoing TO resection (WR 0.64, 95% CI 0.40-0.98). A subgroup analysis of patients classified as not having adjacent tumor involvement at the time of surgery revealed that those patients who underwent multivisceral resection had 33% lower odds of winning compared to TO resection (WR 0.67, 95% CI 0.45-0.99).

CONCLUSIONS: Based on win-ratio assessments of a hierarchical composite endpoint, multivisceral resection in patients without adjacent tumor involvement may not confer improved outcomes. This method supports the rationale for less invasive resection of LPS in select patients, especially older patients.