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

Abstract

Purpose: To assess the clinical outcomes of single or oligo-fractionated stereotactic radiotherapy (SRT) using dynamic conformal arcs (DCA) for head and neck tumors (HNTs).

Methods: 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 22.3 Gy (11.2-32.8) in 2-4 fractions with a median interval of 7 days and 10.4 Gy (9.2-12.4) in one fraction. SRT was combined with upfront conventionally fractionated RT in 48.6 % of patients.

Results: The median follow-up periods were 18.4 months (2-84.1) for the entire cohort and 49.6 months 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 <25.6 cm(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.

Conclusions: 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 ≥25.6 cm(3) were deemed unsuitable for this treatment regimen.

Fig. 1

Kaplan–Meier estimates of overall survival (OS), local control (LC), disease-failure-free (DFF) probability, and the incidence of late adverse events from the commencement of SRT. a OS for the entire cohort, b comparison of OS with or without any disease outside the SRT site, c comparison of LC for PTV< versus ≥25.6 cm³, d comparison of LC between BED_{10 LQ}< versus ≥59.5 Gy, e DFF probability, f the incidence of late adverse events