Clinical outcomes of single or oligo-fractionated stereotactic radiotherapy for head and neck tumors using micromultileaf collimator-based dynamic conformal arcs

Abstract

To assess the clinical outcomes of single or oligo-fractionated stereotactic radiotherapy (SRT) using dynamic conformal arcs (DCA) for head and neck tumors (HNTs). Thirty-four consecutive patients with 35 lesions treated between 2005 and 2009 were retrospectively evaluated, of whom 85.7% had recurrent or metastatic disease, and 45.7 and 34.3% had previous radiotherapy and surgery, respectively. The median SRT dose was 22.3Gy (11.2-32.8) in 2-4 fractions with a median interval of 7days and 10.4Gy (9.2-12.4) in one fraction. SRT was combined with upfront conventionally fractionated RT in 48.6% of patients. The median follow-up periods were 18.4months (2-84.1) for the entire cohort and 49.6months for the survivors. The 1- and 2-year local control (LC) rates were 84.3 and 70.5%, with the 1- and 2-year overall survival (OS) rates of 78.6 and 51.6%. LC was significantly better for tumor volumes <25.6cm(3) (p=0.001). OS was significantly longer in patients without any disease outside the SRT site (p<0.001), whereas LC after the SRT did not affect the OS. Late adverse events occurred in 9 patients, including cranial nerve (CN) injury (grade 3/4) in 2, brain radionecrosis in 5 (grade 1), and fatal bleeding in 2 patients harboring uncontrolled lesions abutting the carotid artery. DCA-based SRT can confer relatively long-term LC with acceptable toxicity in selected patients with HNTs. The patients with CN involvement or tumor volume ≥25.6cm(3) were deemed unsuitable for this treatment regimen.