Patients with head and neck cancer (HNC) are often ineligible for curative therapy such as surgery and definitive radiotherapy (RT) because of advanced age, poor performance status, extent of the tumor, prior treatment, and comorbidities. Patients with HNC often have symptoms such as pain, hemorrhage, dysphagia, and airway compromise which decrease the quality of life (QOL) (1, 2).
RT for incurable HNC has been demonstrated to be an effective palliative modality, even for patients who have received prior RT (2, 3). Currently, no general consensus exists for appropriate palliative RT regimen in HNC. Generally, a once-daily hypofractionated RT regimen of 30 Gy/10 fractions is commonly performed as palliative RT regardless of the tumor site; however, this treatment regimen is not appropriate for HNC because of the acute adverse effects. The reported frequency of Grade 3 or higher acute toxicities with this treatment regimen for patients with HNC was more than 40% (4). Other hypofractionated palliative RT regimens have been reported for HNC. Stevens et al performed palliative RT for 148 patients with newly diagnosed HNC (5). The median RT dose and fraction number were 50 Gy and 20; the most frequently used fractionation regimen was a split course designed to deliver a total dose of 50 Gy in 2.5-Gy fractions within 6 weeks, composed of 2 cycles of 25 Gy in 10 fractions given within 2 weeks, separated by a 2-week break. Overall response was reported in 85 (57%) patients, while 10 (7%) and 8 (5%) patients had unplanned discontinuation and planned RT interruption because of the toxicities, respectively. The “Hypo Trial” conducted by Porceddu et al treated 35 incurable patients with HNC; patients received 30 Gy in 5 fractions at 2/week, at least 3 days apart, with an additional boost of 6 Gy for small volume disease (≤ 3 cm) in suitable patients (6). Tumor response was achieved in 28 (80%) patients. Grade 2 and 3 mucositis were reported in 13 (37%) and 9 (26%) patients, respectively, and Grade 2, 3 and 4 dysphagia were reported in 23 (66%), 4 (11%) and 2 (6%) patients, respectively. These RT regimens provide certain palliative response, however, acute adverse effects, which may decrease patients’ QOL, are still relatively strong.
In the 1980s, the Radiation Therapy Oncology Group (RTOG) performed a phase II study of RT, which consisted of 2 days of twice-daily fractionation with a fraction size of 3.7 Gy (14.8 Gy per cycle) repeated at 3 to 6 week intervals for a total of 3 cycles with an RT dose of 44.4 Gy for pelvic malignancies (7). Thereafter, this RTOG 8502 “QUAD shot” regimen has been successfully adapted for palliative treatment of HNC. The RTOG 8502 regimen for HNC has been reported to achieve tumor response and palliation in approximate 50–85% and 55–100% of patients, respectively. Furthermore, toxicity has been reported to be mild, with Grade 3 toxicity for approximately 0–10% of patients (2, 4, 8–11).
In earlier studies, RTOG 8502 regimen was performed using a 2-dimensional (2D) RT. RT field was typically defined as the gross symptomatic disease plus a 1 to 2 cm margin based on the physical examination (8, 9). The technical development of RT techniques in the last 2 decades, such as 3-dimensional conformal RT (3D-CRT) and intensity-modulated radiotherapy (IMRT) based on the precise target definition using images of computed tomography (CT), provides an enhanced dose concentration to the target volumes and reduces the dose to organs at risk (OAR) (12, 13). The current National Comprehensive Cancer Network (NCCN) guidelines recommend the RTOG 8502 regimen using 3D-CRT or IMRT as one of the palliative RT regimens for HNC (14).
More recently, volumetric modulated arc therapy (VMAT) has been introduced to treat HNC (15). Using this technique, the gantry is rotated while the dose is being delivered, and 3 parameters (dose rate, field shape, and speed of gantry rotation) can be changed as the beam is rotated (16). Compared with conventional fixed-field IMRT, VMAT provides similar excellent dose coverage to the target volume with a reduced dose to OARs. Furthermore, the treatment time of VMAT is much shorter than conventional IMRT; the approximate treatment times are 2 to 4 and 10 to 15 minutes for VMAT and IMRT, respectively (15). Introduction of VMAT into palliative RT regimen with RTOG 8502 may provide good treatment response with reduced toxicities for patients with HNC. To the best of our knowledge, the treatment results of RTOG 8502 regimen using VMAT has not been evaluated. The purpose of this study was to review a single institutional experience of the RTOG 8502 “QUAD shot” regimen using VMAT for incurable HNC.