Role of minor salivary glands in developing patient-rated xerostomia and sticky saliva during day and night.

PURPOSE: The purpose of this prospective study was to investigate the relationship between xerostomia during the day (XERday) and night (XERnight) and sticky saliva during the day (STICday) and night (STICnight) and dose distributions in different major and minor salivary glands among head and neck cancer (HNC) patients treated with primary radiotherapy (RT) or chemoradiation (CHRT).

METHODS AND MATERIALS: The study population was composed of 201 consecutive HNC patients treated with intensity modulated radiotherapy (IMRT) or 3-dimensional conformal radiotherapy (3D-CRT). All patients were included in a standard follow up programme in which acute and late side effects and quality of life (QoL) were prospectively assessed, prior to, during and after treatment. The primary endpoints were XERday, XERnight, STICday, STICnight as assessed by the Groningen Radiotherapy Induced Xerostomia questionnaire (GRIX) six months after completion of treatment. Organs at risk (OARs) potentially involved in salivary function were delineated on planning-CT, including the parotid, submandibular and sublingual glands and the minor glands in the soft palate, buccal mucosa and lips. Patients with moderate-to-severe xerostomia or moderate-to-severe sticky saliva, respectively, at baseline were excluded. In order to determine which salivary glands were most important, a multivariate logistic regression analysis with an extended bootstrapping technique was used.

RESULTS

In total, 29% and 19% of the cases suffered from XERday and XERnight, respectively. The multivariate analysis showed that baseline xerostomia and the mean parotid gland dose were the most important predictors for XERday and XERnight. At 6months after (CH)RT, 10% and 12% of the cases reported STICday and STICnight respectively. We were not able to identify prognostic factors related to dose distributions with regard to STICday. The mean submandibular gland dose was associated with STICnight. Baseline xerostomia and sticky saliva scores on the GRIX were associated with XERday, XERnight, STICday. Increasing age was correlated with both XERnight and STICnight.

CONCLUSION

Organs at risk for XERday and STICday are similar to organs at risk for XERnight and STICnight.