ObjectiveTo study the impacts of radiotherapy on pH values of saliva and nasal secretion in nasopharyngeal carcinoma (NPC) patients.MethodsTestpaper test was applied to detect the pH values of saliva and nasal secretion in normal subjects, NPC patients during radiotherapy and those after radiotherapy, 30 cases in each group. The timepoints of detection for the radiotherapy group included preradiotherapy, one week, three weeks, five weeks and the termination of radiotherapy. The obtained data were analyzed statistically and some related issues were discussed.ResultsThe salivary PH values of the NPC group in preradiotherapy, 1 week, 3 weeks, 5 weeks, and the termination of radiotherapy were 6.98±0.94, 6.13±0.91, 5.50±0.90, 5.52±0.94, and 5.55±1.12 respectively. And that of the postradiotherapy group was 6.11±0.64. Their differences were all statistically significant (all P=0.000). Their corresponding pH values of the nasal secretion were 7.14±0.26, 7.13±0.26, 7.20±0.31, 7.33±0.27, 7.28±0.34 and 7.30±0.31. The nasal secretion pH value before radiotherapy was lower than that at the 5th week during radiotherapy and that of the postradiotherapy group, and their differences were statistically significant (both P<0.05) while other differences were all in significant (all P>0.05).ConclusionsDuring radiotherapy of NPC patients, the salivary PH shows an irreversible downward trend starting at the first week and touching bottom at the third week. On the contrary, the nasal secretion pH value demonstrates a slow ascent with relatively minor change. The reverse changes and the effect of the salivary PH and the nasal cavity PH during radiotherapy of NPC need to be further studied.