Intensity-modulated radiotherapy prevents lasting damage to salivary glands but not oral mucositis.

Objective: This study aimed to assess the salivary protein composition variations in head and neck cancer patients (HNC) undergoing Intensity-Modulated Radiotherapy (IMRT) and examined the correlation with the clinical onset/severity of oral mucositis (OM). Methods: Saliva samples/clinical data were obtained from 40 HNC patients pre-IMRT(T0) and post-IMRT (T1=6m, T2=12m) treated at Guy’s Hospital (ethics approval/consent). Salivary flow rate (SFR), protein concentration (TPC) and secretion rate (TPSR) were determined from unstimulated, whole-mouth saliva samples and compared to pre-treatment levels. Clinical parameters/side effects such as OM was assessed, salivary proteins were quantified using BCA assay, SDS-PAGE/PAS-staining determined MUC5B and MUC7, ELISA assays: IgA, cystatin S and albumin; α-amylase activity by kinetic assays. Results: 95 % patients experienced OM during IMRTwith 33 reaching grade 2&3. Furthermore, 6 months post-IMRT, a significant reduction, in SFR, TPSR, α-amylase and cystatin S compared with baseline. Remarkably IMRT did not significantly alter MUC5B/MUC7, and IgA secretion rates at any timepoint. Moreover, there were significant/negative correlations between IgA concentration at T0 with OM onset/severity during the cancer treatment, (p = 0.006). Conclusion: This study reveals that IMRT prevents damage to salivary glands but does not prevent OM, suggesting that salivary mucins may not be involved in the onset /severity of OM.