The effect of normal tissue doses on quality of life using different radiation techniques in nasopharyngeal cancer

SUMMARY Purpose: The aim of the present study was to evaluate the impact of doses and volumes of the swallowing structures and major salivary glands on quality of life (QOL) in patients with nasopharyngeal carcinoma(NPC) treated with conformal radiotherapy(RT). Patients and Methods:Between 2004 and 2011, 25 patients with NPC who completed RT courses with conventional RT to a dose of 66-70 Gray (Gy) were analyzed at our institution. Parotid, submandibular salivary glands, constrictor pharyngeal muscles, glottic and supraglottic larynx and tongue base volume in 3D was created and QoL was measured using The European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaire (EORTC QLQ) and Head and Neck cancer quality of life questionnaire module (QLQ –H&N35) and QOL scores were calculated in patients. Dose volume histograms (DVH) were analyzed and data of volume and doses of these organs were obtained. The effects of QOL on normal tissue doses especially resulting dry mouth and dysphagia was assessed. Results: All patients received curative RT, and 20 (80%) patients received chemotherapy (CT) during treatment. Socio-demographic characteristics and treatment related effects on QOL were examined and male gender, was found to have a negative effect on physical function score (p=0,02). In patients without comorbid disease and undergoing chemotherapy statistically significant difference was found in development of swallowing problems. (p=0,03; p=0,04). Administration of chemotherapy was found to have a statistically significant effect on trouble with social eating (p=0,03) and less sexuality (p=0,01). A statistically significant relationship was determined between EORTC / Radiation Therapy Oncology Group (RTOG) mucosa, late side effects of salivary glands and the dose and volumes of gross tumour volume (GTV), constrictor pharyngeal muscles and salivary glands. (p<0,05). statistically significant difference was found.In evaluating the relationship between the organ doses and EORTC QLQ-C30; the relationship between overall health score (80.99 ± 19.02) and lower constrictor pharyngeal muscle V65 (p = 0.049) and bilateral parotid gland V26 volume (p = 0.034), and the relationship between emotional function and mean dose of bilateral parotid gland (p = 0.041) was found.to be statistically significant. By analyzing the organ doses with the EORTC QLQ-H & N35 symptom scales the dose and volume of the submandibular gland (p <0.05) demonstrated a statistically significant association with swallowing problems. In development of dry mouth bilateral submandibular gland mean dose was significant (p = 0.039).Present study failed to show a statistically significant relationship between development of swallowing problems, dry mouth and the parotid gland but a statistically significant relationship was found between speech problems and bilateral mean dose of parotid gland (p = 0.014), and sticky saliva was assosciated with the dose and volume of both major salivary glands (p <0.05). Concluion: Patients with NPC treated with conformal radiotherapy, RT dose-volumes in the structures and major salivary secretion tissues responsible for swallowing action were found to have a significant impact of such symptoms like dry mouth, sticky saliva, difficulty in swallowing, speech problems, felling ill, less sexuality as well as on quality of life parameters like emotional, social function and global health. Key Words: Nasopharyngeal cancer, radiotherapy, dry mouth, difficulty in swallowing, quality of life