a report of delayed toxicities of intensity modulated radiation therapy for nasopharyngeal carcinoma: a single center cross-sectional study

Background: based on the literature review, the available information regarding late toxicities after intensity modulated radiation therapy (imrt) for nasopharyngeal carcinoma (npc) is limited to a few countries. objectives: this study provides an opportunity to evaluate the delayed toxicities among iranian patients with npc that underwent imrt. methods: between february 2016 and september 2018, 32 patients were treated with imrt for npc at shohada-e tajrish hospital. the majority of them were in the advanced clinical stage and all received platinum-based induction and/or concurrent chemotherapy. our typical prescription dose was 70.2 gy to the gross tumor volume (gtv) in 2 gy per fraction. uninvolved regional lymph nodes received 59.4 gy. considering the minimum follow-up time of 6 months, we aimed mainly at evaluating the rate of delayed toxicities, including xerostomia, hearing loss, and eyeball damages. toxicities were categorized based on either rtog/eortc or lent/soma criteria. results: the median follow-up time was 12 months (6 - 32 months). the occurrence rates of grade ≥ 2 xerostomia, grade ≥ 2 hearing loss, optic neuropathy, and retinopathy were 28%, 10%, 4%, and 7%, respectively. based on the dose-volume histogram analysis, averages of mean doses to the parotid glands, submandibular glands, oral cavity, and cochlea were 32.3 gy, 58.9 gy, 41.8 gy, and 44.9 gy, respectively. conclusions: our experience of using imrt in the treatment of npc revealed equivalent toxicities (except for hearing loss) in comparison with high-experienced centers.