85: Initial Multivisceral Resection for Retroperitoneal Liposarcoma Does Not Predict Improved Outcomes After Recurrence

Retroperitoneal liposarcomas (RPLPS) have a high propensity for local recurrence. While tumor size, grade, and histology subtype impact rate of relapse, the role of en bloc tumor resection with adjacent organs to prevent local recurrence is unclear. This study evaluates the association between extent of tumor resection for RPLPS and recurrence outcomes.


Methods:

Retrospective chart review was performed for patients who underwent surgical resection of recurrent RPLPS at a tertiary referral center between 2010 and 2022. Patients were categorized into those who had isolated tumor resection only (ISO), and those who underwent en bloc resection of tumor with at least one adjacent organ (ENBLOC). Demographics, tumor characteristics, and recurrence patterns were analyzed.


Results:

A total of 94 patients underwent surgery for recurrent RPLPS: 26 (28%) in the ISO group and 68 (72%) in the ENBLOC group. Patient age, race, and distance from the hospital were comparable. Of the ENBLOC cohort, the kidney (62%), colon (43%), and spleen (24%) were the most commonly resected organs. At initial surgery, the rate of de-differentiated LPS (46% ISO vs 49% ENBLOC, p=0.837) and R0 margins (31% ISO vs 38% ENBLOC, p=0.500) were similar; however, primary tumor size was larger in the ENBLOC cohort (20 cm vs 15 cm, p=0.047). At surgery for 1^st recurrence, 97% were repeat local resections and a majority in both cohorts required resection with adjacent organs (71% ISO vs 67% ENBLOC, p=0.744). Intraoperative radiation was administered in 31% of ISO and 29% of ENBLOC patients during repeat surgery. 56% of all RPLPS patients had a 3^rd resection and 28% underwent a 4^th operation. Compared to ISO, the ENBLOC cohort exhibited no difference in time to 1^st recurrence (25 months ISO vs 18 months ENBLOC, p=0.356) or subsequent relapses (2^nd recurrence: 16 vs 17 months, p=0.932; 3^rd recurrence: 10 vs 11 months, p=0.525). Patients in the ISO group had a higher 3-year survival (96% vs 75%, p=0.02) but similar 5-year survival (73% vs 60%, p=0.249).


Conclusions:

Despite the belief that resecting adjacent organs en bloc with RPLPS may decrease recurrence rates, this did not result in higher rates of R0 resection or longer interval to disease recurrence in our study. Therefore, in the absence of gross tumor involvement of adjacent organs, multivisceral resection should be considered carefully as additional survival benefit may be limited.