IMRT: preliminary results in a series of advanced head-and-neck cancer patients

ABSTRACT

PURPOSE: To determine retrospectively 2-3 year local and regional control (LRC), free-of-disease survival (FDS) and overall survival (OS), as well as summarized toxicities in a group of 31 advanced head-and-neck cancer patients, treated at our institution between 2004 and 2011 with definitive IMRT low-dose concomitant boost, the majority of them with concurrent chemotherapy based on cisplatin. The results are also shown in the sub-group of nasopharyngeal cancer patients (NPC 15 cases). PATIENTS AND METHODS: Radiological basal and contrasted CT series, MR-CT or PET/CT fused images in the setup position with immobilization mask were registered in simulation therapy patients. Planed doses were 70 Gy in primary tumor and positive nodes >1 cm; 63 Gy in high-risk areas of microscopic diseases +10 mm safety margin; and 56 Gy in low risk of diseases regional lymph nodes. Treatment was delivered using a Varian 2100 Clinac with sliding windows IMRT. Spinal cord doses were limited to a strict maximum of 45 Gy, and optimization aimed for mean doses in parotid glands below 26 Gy, especially in the contralateral parotid gland. Online DRR-portal X-ray comparison images were taken every day with a deviation module tolerance ≤3 mm. RESULTS: The mean follow-up since IMRT was 34 months (interval 8-89; median 31 months). Median follow-up in living patients was 22 months. The 2-year rate for global LRC was 64 %, for FDS 61 % and OS 77 %. For the NPC group after 2 years, LRC was 73 %, FDS 73 % and OS 93 %. The 3-year rates were similar. Seven patients died as a consequence of local and/or regional progression (mean time 10 months). Relapses were observed in eight patients (26 %), but only seven could be confirmed by biopsy (22.6 %; mean time to relapse 8.6 months). Global acute mucositis was 61 % and chronic mucositis was shown in six cases which developed xerostomia (19 %) in the first control after IMRT, but 1 year later it was reduced to only four patients, two Grade 2 and two Grade 1. CONCLUSIONS: No excessive, unwarranted toxicities were observed using concomitant low doses boost in IMRT. High rates of compliance to concurrent chemotherapy were achieved. Late xerostomia associated with this regime decreased 1 year after conclusion of treatment. The implementation of IMRT requires advances in imaging for better tumor delineation; otherwise the physician loses the advantage of dose modulation or faces a risk of geographical miss (AU)