First results of a phase III multicenter randomized controlled trial of intensity modulated (IMRT) versus conventional radiotherapy (RT) in head and neck cancer (PARSPORT: ISRCTN48243537; CRUK/03/005)

Abstract

LBA6006 Background: Xerostomia is the most common late toxicity of RT to the head and neck. IMRT dose distributions reduce the dose delivered to parotid gland. PARSPORT investigated the role of IMRT in reducing xerostomia in patients with head and neck cancer. Methods: The PARSPORT trial compared two radiotherapy delivery methods in the treatment of patients with pharyngeal tumors (T1–4, N0–3, M0). Patients received 65Gy in 30 fractions over 6 weeks delivered using either CT planned parallel opposed lateral fields or parotid-sparing IMRT. Stratification was by site of tumor and center. The primary endpoint was incidence of LENT-SOMA ≥G2 xerostomia one year after treatment. Secondary endpoints included acute toxicities (CTCAE v3) and other late RTOG and LENT-SOMA radiation toxicities. Proportions of patients with ≥G2 toxicity were compared using exact tests. For secondary endpoints a significance level of 1% was used. Results: 94 patients (47 RT; 47 IMRT) were randomized between 2003 and 2007 from six UK centers. 80 patients had oropharyngeal tumors and 14 hypopharyngeal. Radiotherapy was given as primary treatment in 71 patients and post-operatively in 23. 22 patients had AJCC stage I/II disease. Median follow-up was 31.9 months (IQR: 26.6 –38.8). Twelve month LENT-SOMA ≥G2 xerostomia scores were observed in 74% (25/34) of RT and 40% (15/38) of IMRT patients (p=0.005). Corresponding values at 18 months were 71% (15/21) and 29% (9/31) (p=0.004). On the RTOG scale, 12 month ≥G2 xerostomia was reported in 64% (21/33) RT vs 41% (15/37) IMRT patients (p=0.06). The 18 month incidence was 81% 17/21 RT vs 20% (6/30) IMRT (p<0.001). Acute radiotherapy related ≥G2 fatigue was more prevalent in the IMRT group (76% vs 41% p=0.001). No differences in acute mucositis or pain scores were seen. At 12 months, no statistically significant differences were seen in other late toxicities. No differences were observed between overall survival and locoregional control rates. Conclusions: Sparing the salivary glands through use of IMRT significantly reduces the incidence of xerostomia in patients with pharyngeal tumors. [Table: see text]