P63: Is there a benefit to radiation and surgery in specific histologic subtypes of retroperitoneal sarcoma?

Friday, March 24, 2023

12:41 PM – 12:46 PM

Location: SSO HUB: Melanoma & Sarcoma Zone

Author(s)

Chee-Chee H. Stucky, MD

Assistant Professor of Surgery
Mayo Clinic
Scottsdale, Arizona, United States

Disclosure(s): No financial relationships to disclose

Poster Presenter(s)

Anagha Deshpande, MS

medical student
Mayo Clinic Alix School of Medicine, Scottsdale, Arizona, United States

Disclosure information not submitted.

Author(s)

RB

Richard Butterfield, M.A.

Biostatistician
Department of Biostatistics, Mayo Clinic Arizona, United States

Disclosure information not submitted.
JA

Jonathan Ashman, MD

Professor of Radiation Oncology
Mayo Clinic Arizona, United States

Disclosure information not submitted.
Sanjay P. Bagaria, MD

Professor of Surgery
Mayo Clinic
Jacksonville, FL, United States

Disclosure information not submitted.
Travis E. Grotz, MD

Assistant Professor
Mayo Clinic
Rochester, Minnesota, United States

Disclosure(s): No financial relationships to disclose
CT

Cornelius A. Thiels, DO, MBA

Assistant Professor
Division of Hepatobiliary and Pancreas Surgery, Mayo Clinic, United States

Disclosure information not submitted.
Nabil Wasif, MD, MPH

Professor of Surgery
Mayo Clinic Arizona
Phoenix, Arizona, United States

Disclosure information not submitted.

Disclosure(s):

Chee-Chee H. Stucky, MD: No financial relationships to disclose

Travis E. Grotz, MD: No financial relationships to disclose

Introduction: Recently, the STRASS Trial discouraged routine use of radiation and surgery (SurgRT) to treat retroperitoneal sarcoma (RPS) noting a possible benefit only in well-differentiated liposarcoma (WDL). We analyzed RPS outcomes by histologic subtype, use of SurgRT and intraoperative radiation therapy (IORT).

Methods: 222 patients undergoing R0/R1 resection were studied retrospectively. We defined local recurrence (LR) as tumor at the site of resection performed at our institution and distant recurrence (DR) as intraperitoneal disease, tumor away from resection, or distant metastases. Univariate predictors of LR and local or distant recurrence (LDR) (accounting for death as competing risk), local recurrence-free survival (LRFS), disease free survival (DFS) and overall survival (OS) were compared between treatment modalities and histologic subtype using Gray k-sample and Logrank tests.

Results:

157 patients had SurgRT: 28.7% WDL, 37.6% de-differentiated/pleomorphic sarcoma (DDPS), 28.7% leiomyosarcoma (LMS). Median follow-up=55 months and median OS=89 months (78-123 months). DDPS and LMS were associated with worse OS (p < 0.001), LRFS (p=0.001) and DFS (p < 0.001). 5-year LR was associated with histology (26% WDL, 45% DDPS, 18% LMS, p=0.0015) as was 5-year LDR (26% WDL, 53% DDPS, 51% LMS, p=0.0013).

Overall, SurgRT did not affect OS or DFS but trended toward improved LRFS (p=0.160). SurgRT was significantly associated with improved LR as well as LDR (Table 1). By histology, SurgRT was associated with improved LRFS in DDPS (p=0.0181) and LMS (p=0.0180) but not WDL (p=0.7237).

Among IORT patients who received radiation (n=113), 33 (29%) experienced LR, 50% of these recurred at the site of IORT. There was no benefit in DFS or LRFS with IORT and slightly worse OS (Table 1). IORT was associated with improved LDR [HR=0.51 (CI=0.31-0.83), p=0.0093] but not LR. This finding was upheld when primary and recurrent tumors were analyzed separately (p=0.0041 and p=0.0185, respectively).

Conclusions: SurgRT improves LR in DDPS and LMS but not WDL. While no true survival benefit is seen by RT, it is possible that patients with lower LR risk after SurgRT may ultimately experience improved quality of life.

Learning Objectives:

list histologic subtypes in retroperitoneal subtypes that may benefit from surgery plus radiation therapy.
describe risks of local recurrence in retroperitoneal sarcoma.
define benefits of intraoperative radiation therapy in the treatment of retroperitoneal sarcoma.