428P - Prognostic value of clinico-pathological characteristics and peripheral monocyte counts in localised extra-meningeal solitary fibrous tumours treated with surgical resection

Background

Solitary Fibrous Tumour (SFT) is a rare soft tissue neoplasm with an intermediate biologic potential. The aim of this study was to investigate clinical and pathological factors as well as peripheral blood counts to determine factors predicting for likelihood of early recurrence and poor survival in extra-meningeal SFTs after surgical resection.

Methods

We retrieved the records of 101 patients that were consecutively diagnosed with SFT from 1996-2019 at the National Cancer Centre Singapore and Singapore General Hospital. 19 patients were excluded from the study, of which 6 had distant metastasis at diagnosis, 5 did not undergo curative surgery and 8 were meningeal SFTs that are known to have a poor prognosis. The remaining 82 cases of extra-meningeal SFTs that underwent curative surgery were retrospectively examined with survival analyses performed using the Kaplan-Meier method and multivariate Cox proportional models.

Results

The cohort consisted of 37 men and 45 women with a median age of 51 years (range, 13-87). The primary site of the tumour was abdominopelvic in 18 (22.0%), limbs/trunk in 27 (32.9%), pulmonary/pleura in 18 (22.0%) and head/neck in 19 (23.2%). Median tumour size was 5.0 cm (range, 1.4-30.0). The 5-year overall survival (OS) and event-free survival (EFS) was 92.4% and 79.2% respectively. On univariate analysis, advanced age was prognostic for worse OS, while an abdominopelvic site, lymphocytosis (>2.2 x 10⁹/L) and monocytosis (>0.56 x 10⁹/L) were prognostic for both worse OS and EFS. On multivariate analysis, only age, abdominopelvic site and monocytosis remained independently prognostic for OS, while abdominopelvic site and monocytosis were retained as independently prognostic factors for EFS (all p < 0.05). Tumour depth, tumour size, resection margin, tumour necrosis and mitotic count were not significantly prognostic.

Conclusions

In extra-meningeal SFT, clinical factors including advanced age and abdominopelvic location indicate poor prognosis. In addition, peripheral monocytosis at diagnosis may serve as a novel and easily obtained biomarker for further prognostication.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

National Cancer Centre Singapore.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.