Does radiation dose to the salivary glands and oral cavity predict patient-rated xerostomia and sticky saliva in head and neck cancer patients treated with curative radiotherapy?

Abstract

Background and Purpose To investigate the association between the mean salivary gland and oral cavity dose, with patient-rated moderate and severe xerostomia and sticky saliva. Patients and methods One hundred and fifty-seven patients treated with bilateral irradiation for head and neck cancer were included. The parotid and submandibular glands and the oral cavity were delineated on plannings-CT scans. At baseline and 6 and 12 months self-reported xerostomia and sticky saliva were assessed using the EORTC QLQ-H&N35 questionnaire. Results At 6 months a significant association between the mean parotid (MD par) and mean submandibular dose (MD subm) and xerostomia was observed (OR−MD par: 1.17; P=0.002 and OR−MD subm: 1.08; P=0.02). Between MD par and MD subm, a significant interaction term was present. No significant association was found with the oral cavity dose. Xerostomia was reversible depending on MD par and MD subm. Considering Sticky saliva, a significant association was found at 6 and 12 months with MD subm (OR: 1.03; P<0.001). The P50 for sticky saliva increased with elapsing time. Conclusions Both MD par and MD subm influence the risk of xerostomia in irradiated patients at 6 months. This probability as a function of the mean parotid dose significantly depended on the mean dose in the submandibular glands. Sticky saliva mainly depends on MD subm.