Saliva electrolyte analysis and xerostomia-related quality of life in nasopharyngeal carcinoma patients following intensity-modulated radiation therapy

Background and purpose: Nasopharyngeal carcinoma (NPC) is one of the most common cancers in southern China and the first-line treatment is radiotherapy. Intensity-modulated radiation therapy (IMRT) can deliver high dose to cancer and low dose to normal tissue, but xerostomia is still one of the complications after IMRT. However, how the concentration of saliva electrolytes be affected by IMRT and the effects on the quality of life are still unknown. In this prospective study, 76 NPC patients were recruited from hospitals in Hong Kong to identify the change of saliva electrolytes and xerostomia-related quality of life before and after IMRT.

Methods and materials: Saliva and questionnaire were collected before IMRT, 1 month, 3 months, 6 months and 12 months after IMRT. The concentration of saliva electrolytes was detected using inductively coupled plasma-optical emission spectroscopy (ICP-OES).

Results: Saliva flow rate significantly decreased after IMRT. Decrease in the mean value of pH was observed but the difference is not statistically significant. The concentrations of potassium, iodine, and calcium decreased and chloride concentration increased after IMRT, while the concentrations of sodium, magnesium, copper or zinc were kept at the same level before and after treatment. Xerostomia-related quality of life was adversely affected by IMRT, but partially recovered after 1 year.

Conclusions: Our study revealed the change of saliva electrolytes and xerostomia-related quality of life in patients undergone IMRT for NPC.