Non‑endemic non‑keratinizing nasopharyngeal carcinoma: Long‑term toxicity following chemoradiation

Chemoradiotherapy (CRT) is considered the standard of care for non-keratinizing nasopharyngeal carcinoma (NK-NPC) worldwide, with improved overall survival, local recurrence-free survival and distant metastasis-free survival rates compared with radiotherapy alone. However, CRT is associated with late toxicities that can diminish a patient's quality of life and increase morbidity and mortality rates. Following the geographical distribution of NK-NPC, research has predominantly been performed on the endemic Asian population of patients. To extrapolate these results, more investigations in non-Asian populations are needed. The present study aimed to analyze the occurrence and severity of late toxicities following CRT strictly in patients with non-endemic NK-NPC. The clinical retrospective study included 36 patients >18 years of age with pathohistologically confirmed NK-NPC who were treated in the Institute of Oncology and Radiology of Serbia (Begrade, Serbia) with CRT during a 5-year period (January 2015 to December 2020). After completing combined treatment with a mean tumor dose of 68.64Gy and a median of 4 cycles of weekly cisplatin (40 mg/m²), late sequelae were routinely assessed during regular follow-ups and graded according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer 'Late Radiation Morbidity Scoring Schema'. Overall late toxicities were registered in 83.3% of the patients, mostly at grade ≤2. Neck fibrosis was observed in 69.44% and xerostomia in 58.33% of patients. Late dysphagia was experienced by 2 patients, secondary hypothyroidism by 4 patients and neuropathy by 3 patients. In conclusion, based on the results of the present study, late toxicities can be expected in the majority of patients with non-endemic NK-NPC following CRT. However, late sequelae are of lower grade, with neck fibrosis and xerostomia being the most predominant.