(P 275) ASSESSMENT OF SURGICAL MARGIN CLASSIFICATION FOR SOFT TISSUE SARCOMA: DEFINITIONS OF ADEQUATE MARGINS SYSTEM FOR PLANNING AND EVALUATION

Author(s)

Toshihiko Nishisho, MD.PhD

Medical doctor
Department of Orthopedics Institute of Biomedical Sciences
Tokushima, Tokushima, Japan

Co-Author(s)

ST

Shunichi Toki, MD.PhD

Department of Orthopedics Institute of Biomedical Sciences
Tokushima, Tokushima, Japan
RM

Ryo Miyagi, MD

Department of Orthopaedic Surgery, Tokushima Prefectural Central Hospital
Tokushima, Tokushima, Japan
KS

Koichi Sairyo, MD. PhD

Department of Orthopedics Institute of Biomedical Sciences
Tokushima, Tokushima, Japan

Objective: There are many classification systems to determine the postoperative margin status of soft tissue sarcoma (STS), however, it is not clear which is the best system to predict local recurrence accurately. The aim of this study is to evaluate the best margin classification system for prediction of local recurrence.

Methods: We retrospectively reviewed the data of 58 patients diagnosed with soft tissue sarcoma between 2011 and 2020. Local recurrence free survival (LRFS) rates after surgical treatment of STS were compared among different classifications; Enneking classification (CORR 1980), the R classification, the Union International Contre le Cancer (UICC) classification (R+1 mm classification), Kawaguchi classification (CORR 1994) by Kaplan-Meier method (Log-rank test). All statistical analyses were performed using R3.6.3.

Results: Average follow-up time was 41 months. The 5-year overall survival was 68.9%, and 5-year LRFS was 91.7%. Local recurrence was occurred in 4 patients. Nine patients underwent neoadjuvant or adjuvant radiotherapy in which case there was no local recurrence. Enneking classification had no relationship with local recurrence. The local recurrence was significantly lower in R0 of R0 classification (p=0.008), R0 of R+1 classification (p=0.03), and more than wide-1cm procedure of Kawaguchi classification (p=0.03), but was not significantly difference more than wide-2cm procedure of Kawaguchi classification (p=0.2). Univariate analysis (Mann-Whitney U test and Fisher exact test) revelated that the risk factors significantly associated with positive margin were tumor size (p=0.0024) and amount of bleeding at the sugary (p=0.0018).

Conclusion: Our data suggested that R classification could be considered the most successful predictor of treatment outcomes of local recurrence. A resection margin of less than 1cm was a risk factor of local recurrence.