Salivary status in patients treated for head and neck cancer

The objective of this study was to compare unstimulated salivary flow rate and residual salivary volume (the volume of saliva retained in the mouth after swallowing) in a group of 23 control subjects and a group of 25 patients who had received radiation treatment or had undergone removal of the salivary glands (or both) for head and neck cancer. As expected, the mean flow rate (+/- 0 standard deviation) in the patient group was significantly less than that in the control group (0.07 +/- 0.11 and 0.45 +/- 0 0.27 mL/min, respectively). However, the mean residual volumes were not significantly different between the 2 groups (0.70 +/- 0 0.28 and 0.82 +/- 0 0.26 mL, respectively). The 25 patients were subdivided according to their self-reported assessment of the mouth as being not dry (3), somewhat dry (12) or very dry (10); mean residual volume of saliva was significantly lower, at 71% the level in control subjects, for the group with very dry mouth (p < 0.02). These results suggest that people who report that the mouth is dry may not have a complete lack of fluid in the mouth; rather, there may be localized areas of dryness, notably on the hard palate, where the salivary film is particularly thin and subject to fluid absorption or evaporation because of mouth breathing.