Parotid Gland Stem Cell Sparing Radiation Therapy for Patients With Head and Neck Cancer: A Double-Blind Randomized Controlled Trial
R.J.H.M. Steenbakkers, Maria I. van Rijn–Dekker, Monique A. Stokman, R.G.J. Kierkels, A. van der Schaaf, Johanna G.M. van den Hoek, Hendrik P. Bijl, Maria C.A. Kramer, Robert P. Coppes, Johannes A. Langendijk, Peter van Luijk
Abstract
PURPOSE: Radiation therapy for head and neck cancer frequently leads to salivary gland damage and subsequent xerostomia. The radiation response of the parotid glands of rats, mice, and patients critically depends on dose to parotid gland stem cells, mainly located in the gland's main ducts (stem cell rich [SCR] region). Therefore, this double-blind randomized controlled trial aimed to test the hypothesis that parotid gland stem cell sparing radiation therapy preserves parotid gland function better than currently used whole parotid gland sparing radiation therapy. METHODS AND MATERIALS: ). Secondary endpoints were several aspects of xerostomia 12 months after treatment. RESULTS: compared with 2 (4.9%) in the standard arm (P = 1.00). However, a trend toward better relative parotid gland salivary function in favor of SCS radiation therapy was shown. Moreover, multivariable analysis showed that mean contralateral SCR region dose was the strongest dosimetric predictor for moderate-to-severe patient-rated daytime xerostomia and grade ≥2 physician-rated xerostomia, the latter including reported alteration in diet. CONCLUSIONS: No significantly better parotid function was observed in SCS radiation therapy. However, additional multivariable analysis showed that dose to the SCR region was more predictive of the development of parotid gland function-related xerostomia endpoints than dose to the entire parotid gland.