Outcomes and prognostic factors of post-irradiation and de novo sarcomas of the head and neck: a histologically matched case-control study.

Background: This study was designed to compare post-irradiation sarcomas (PIS) and de novo sarcomas (DN) of the head and neck in terms of tumor characteristics, prognostic factors, and survival outcomes.

Methods: All (N=83) head and neck sarcoma patients treated at National Cancer Centre, Singapore (Feb 2002-May 2011) were included: DN (N=60; 72%); PIS (N=23; 28%). Clinicopathologic features and outcomes of all patients and histologically matched pairs were compared. Prognostic factors were identified using univariate and multivariate analyses.

Results: Median age, gender, smoking status, and tumor size were not significantly different. Significant differences were seen in histology (most prevalent: PIS-sarcoma-NOS; DN-angiosarcoma) and tumor subsite (most prevalent: PIS-nasal cavity and sinuses; DN-skin). Median latency of PIS development was 16.7 years. PIS patients had shorter overall survival (OS) and disease-specific survival (DSS) compared with DN patients, most clearly seen on histologically matched pair analysis: 2-year OS (PIS: 54%; DN: 83%; P=0.028). Multivariate analyses showed that age>50 years (hazard ratio (HR)=3.68; P=0.007), ever-smokers (HR=2.79; P=0.017), and larger tumor-size (cm) (HR=1.12; P=0.045) were associated with worse OS, and age at >50 years (HR=2.77; P=0.04) and ever-smokers (HR=2.94; P=0.021) were associated with worse DSS. When treated with curative intent, no significant survival difference was noted between DN and PIS patients.

Conclusions: In our cohort, PIS constituted 28% of head and neck sarcomas. Poorer prognosis traditionally associated with PIS compared with DN was not seen amongst patients treated with curative intent.