(P 82) PROGNOSTIC FACTORS AND OUTCOMES OF 275 PATIENTS WITH HEAD AND NECK BONE AND SOFT TISSUE SARCOMA: A SINGLE CENTRE COHORT STUDY

Objective: Head and neck sarcomas (HNS) are a heterogenous group of cancers that are surgically and medically difficult to treat. Despite their low incidence (1% of head & neck malignancies, 5% of all sarcomas), outcomes worldwide are dismal with poor overall survival and high local recurrence rates, prompting urgent attention. Due to the rarity and diversity of HNS, our current understanding of HNS prognosis and treatment is limited. Moreover, the existing body of knowledge mostly comprises published studies describing HNS within predominantly Western populations, and may not adequately represent other cohorts around the world. This study aims to expand the collective understanding of head and neck sarcomas (HNS) and their prognostic factors within a Southeast Asian context.

Methods: 275 HNS patients seen at the National Cancer Centre Singapore were identified from the institution’s database. Overall survival (OS) and progression free Interval (PFI) were calculated using the Kaplan-Meier method. OS was defined as time from the date of diagnosis till the date of patient death. PFI was defined as time from the date of diagnosis till the date of disease recurrence or progression. Recurrence was identified in patients who presented with localised disease at diagnosis without gross residual tumour post-resection, or had complete response to radiotherapy and/or chemotherapy. Progression was identified in patients who did not meet these criteria. Between group survival comparisons were conducted using the log-rank test. Prognostic factors were identified via Cox proportional hazards regression analyses.

Results: Median follow-up time was 39 months (95%CI 25.5, 50.9). Overall mean age was 55.2 years (standard deviation, 20.4 years). Majority of the patients (73.5%) were of Chinese ethnicity. Indians and Malays each made up 5.8% of the cohort, while the remaining 14.9% consisted of other minority races. The 3-year OS and PFI was 52.7% (95%CI 46.0%, 60.3%) and 47.1% (95%CI 39.6%, 56.0%) respectively. Multivariate Cox regression analysis revealed increasing age (HR 1.04, 95%CI 1.02, 1.05), absence of distant metastasis at diagnosis (HR 0.24, 95%CI 0.14, 0.39), radiotherapy induced disease (HR 3.02, 95%CI 1.71, 5.31), and wide surgical excision (HR 0.42, 95%CI 0.24, 0.73) as independent prognostic factors for OS. Primary disease sited at the scalp (HR 2.37, 95%CI 1.07, 5.28; relative to bone) and absence of distant metastasis at diagnosis (HR 0.10, 95%CI 0.05, 0.18) were identified as independent prognostic factors for PFI.

Conclusion: Our results support wide surgical excision in treating HNS within our cohort. We have also identified other factors of significant prognostic value. Compared with bone sarcomas, only soft tissue sarcoma with primary disease sited at the scalp demonstrated a significant difference in patient outcomes in our analysis. Interestingly, the use of chemotherapy and radiotherapy did not result in any significant difference in patient outcomes. Overall, this study represents one of the largest single-institution cohorts in the literature to date, and provides crucial insights towards predicting HNS outcomes. Long term follow up and further analysis are required to integrate our identified prognostic factors into risk stratification algorithms and optimise treatment.