Correlation between initial salivary flow rate and radiation dose in the production of xerostomia.

Dose and initial flow rate are two of several factors that influence the outcome of xerostomia when irradiating head and neck tumors. These two parameters were analysed in 11 irradiated patients where most salivary glands were in the radiation field. Unstimulated whole saliva samples were collected before, during and after the irradiation. The results indicate a statistically significant linear correlation between initial saliva flow rate and the accumulated dose causing irreversible xerostomia. This phenomenon is explained. A diagram is made that could be used (in head and neck tumors where one side could be spared) as a indicator of the maximum dose the salivary glands in the contralateral non-involved side can receive before reaching irreversible dryness.