Effect of Radiation on Saliva Flow Rate in Patients under Head and Neck Radiotherapy

The aim of this study was to eva-luate the salivation flow rate objectively using Schirmer test; and mouth dryness and other con¬sequences subjectively by distributing question¬naires to patients receiving head and neck radio¬therapy. In this descriptive study that was carried out at Imam Khomeini hospital, Tehran, Iran, the saliva flow rate of 33 patients receiving radiotherapy was evaluated in millimeter in 5 minutes using Schirmer test (with a filtered paper calibrated from 1 to 35mm) before treatment, two weeks and four weeks after and at the end of treatment thus having four groups of measurements. Mouth dryness and other consequences were recorded by questionnaire at final stage. Friedman test, chi- square, dependent and independent t-tests were applied to analyze the data. In all four groups, the mean of the saliva flow rate decrease during treatment was significant and followed a descending pattern. At the end of the treatment, the total received dosage and saliva flow rate had an inverse relationship, (P value=0.000). The mean salivation decrease in bilateral radiation was estimated more than unilateral one; though their relation was not statistically significant (P value=0.251). The mean salivation decrease in bilateral radiation of nasopharyngeal cancer was meaningfully greater than unilateral (P value 0.05). During radiation, saliva flow rate depends on the total dosage and the radiation site. Increasing the total dosage of radiation and the field diameter would result in the decrease of salivation of the major salivary glands, particularly parotid ones.