EGF in parotid saliva of head and neck cancer patients

Epidermal growth factor (EGF) present in saliva has a critical role in maintenance and healing of oral mucosa. Head and neck cancer patients undergoing radiation therapy often experience xerostomia as well as changes in taste acuity. Typically, patients who recovered their taste perception reported doing so starting around three months post-treatment (Yamashita et al, Int J Radiat Biol Phys 2006; Weltens et al, Radiother Oncol, 2002). Objectives: The goal of this project was to investigate pre- and post-radiation changes in concentration and total salivary EGF in head and neck cancer patients. Methods: EGF in parotid saliva from 27 patients and unstimulated saliva from a subpopulation (n=5) of these patients was quantified by an enzyme linked immunosorbent assay.  EGF concentration in pg/ml was determined and total EGF (pg) was calculated from the total volume collected.  Results: At 3 months, there was a trend towards decreased EGF concentration and total EGF in stimulated saliva, which was also observed at 6 and 12 months post-radiation.  The decrease in EGF concentration at 6 months was statistically significant (p=0.04). Similar trends were observed when data from unstimulated and stimulated parotid saliva samples were combined. Conclusion: The decrease of EGF at three months post-treatment coincides with a reported improvement in taste at this time point (Yamashita H, Nakagawa K, Nakamura N, et al, Int J Radiat Biol Phys. 2006; Maes A, Hugh I, Weltens C, et al, Radiother Oncol, 2002). Thus, patients who receive parotid-sparing radiation therapy produce substantial amounts of EGF from the parotid, which may have implications for recovery of taste loss and mucosal healing. [This work was supported by K12 RR017607-01 (CAMK) and NIDCR DE16920, DE018512 (NJD)].