Structural evaluation of Parotid gland in post radiotherapy oral cancer patients: A prospective study

Background: To evaluate structural variation of the parotid gland in postradiotherapy oral carcinoma patients. Material and Methods: 52 patients (33 males, 19 females) with histologically confirmed cancer of head and neck region were enrolled. All the patients underwent intensity modulated radiotherapy (IMRT) with linear accelerator. A quantitative analysis was conducted with the help of contrast enhanced computed tomography (CECT) scan regarding the changes in the volume and density of the parotid glands (PGs) along with the assessment of their interrelationship in relation to the mean dose applied to the glands. The evaluations were done immediately after radiotherapy, and after 2 and 3 years. Results: Parotid size reduction was observed in 77.77 % of cases immediately after radiotherapy with a mean dose of 26.66 Gy applied to the parotid glands. Parotid shrinkage reduced to 61.5 % cases three years post radiotherapy. High density changes were revealed by 69.2 % cases immediately after radiotherapy with a mean dose of 34.53 Gy applied to these parotid glands. Low density changes were revealed by 48.1 % cases after 2 years follow up which further reduced to 25 % at three years follow up. Conclusion: There was evidence of structural variation in the PGs during the course of IMRT which was significantly related with the mean dose applied to them. There were high density changes and low density changes immediately after radiotherapy and 2-3 years post-radiotherapy respectively. Further there was volumetric shrinkage post-radiotherapy which shows recovery 2 and 3 years post-radiotherapy.