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Objective: To evaluate longitudinal changes in parotid volumes and saliva production over 2 years after 30 Gy irradiation. Methods: We retrospectively evaluated 15 assessable patients treated for advanced oral cancer. Eligibility criteria were a pathologic diagnosis of squamous cell carcinoma, preoperative radiation therapy with a total dose of 30 Gy delivered in 15 fractions, and the availability of longitudinal data of morphological assessments by computed tomography and functional assessments with the Saxon test spanning 2 years after radiation therapy. In the Saxon test, saliva production was measured by weighing a folded sterile gauze pad before and after chewing; the low-normal value is 2 g/2 min. Repeated-measures analysis of variance with Bonferroni adjustment for multiple comparisons was used to determine the longitudinal changes. Results: The normalized ipsilateral parotid volumes 2 weeks and 6-, 12- and 24 months after radiation therapy were found to be 72.5, 63.7, 66.9 and 78.1%, respectively; the normalized contralateral volumes were 69.8, 64.6, 72.2 and 82.0%, respectively. The bilateral parotid volumes were significantly decreased after radiation therapy (P , 0.01). The nadir appeared at 6 months post-radiation therapy and the volumes substantially recuperated 24 months after radiation therapy (P , 0.01). Mean saliva production before radiation therapy was 3.7 g; the longitudinal changes after radiation therapy were 31.3, 38.0, 43.3 and 69.6%, respectively. Substantial recuperation of saliva production was observed 24 months after radiation therapy (P ¼ 0.01). Conclusions: Although parotid volumes and saliva production were decreased after 30 Gy irradiation, we observed the recuperation of morphological and functional changes in the parotid glands 2 years after radiation therapy.

Objective: To evaluate whether saliva production reflects the parotid volume during the course of radiation therapy (RT) in patients with head-and-neck cancer. Methods: Twenty patients with advanced oral squamous cell carcinomas, who were treated with preoperative chemo-RT, underwent morphological assessment with CT or MRI and functional assessment with the Saxon test. For the Saxon test, saliva production was measured by weighing a gauze pad before and 2 min after chewing without swallowing; the low-normal value is 2 g. Saliva production and parotid volumes before and 2 weeks after RT were compared with the paired t-test, the Spearman rank correlation test and the Fisher exact test. Results: After 30 Gy irradiation, mean saliva production was decreased from 4.2 to 1.0 g (P , 0.01); the reduction in saliva production ranged from 1.7 to 5.4 g (mean 3.2 g). The mean parotid volume was decreased from 68.2 to 47.9 cm 3 (P , 0.01); the post-RT:pre-RT parotid volume ratio ranged from 54% to 85% (mean 71%). Although the initial parotid volume was correlated with initial saliva production (r ¼ 0.47, P ¼ 0.04), no significant correlation was noted after RT (r ¼ 0.08, P ¼ 0.71), and there were considerable individual variations. The parotid volume ratio was inversely correlated with the saliva-reduction amount (r ¼ 2 0.79, P , 0.01). Conclusions: There was a correlation between decreased parotid gland volume and decreased saliva production in patients with head-and-neck cancer undergoing RT. Parotid volume reduction may predict parotid gland function.