A comparison of mean parotid gland dose with measures of parotid gland function after radiotherapy for head-and-neck cancer:Implications for future trials

Purpose: To determine the most adequate parameter to measure the consequences of reducing the parotid gland dose.Methods and Materials: One hundred eight patients treated with radiotherapy for various malignancies of the head and neck were prospectively evaluated using three methods. Parotid gland function was objectively determined by measuring stimulated parotid flow using Lashley cups and scintigraphy. To assess xerostomia-related quality of life, the head-and-neck cancer module European Organization for Research and Treatment of Cancer QLQ (Quality of Life Questionnaire) H&N35 was used. Measurements took place before radiotherapy and 6 weeks and 12 months after the completion of radiotherapy. Complication was defined for each method using cutoff values. The correlation between these complications and the mean parotid gland dose was investigated to find the best measure for parotid gland function.Results: For both flow and scintigraphy data, the best definition for objective parotid gland toxicity seemed to be reduction of stimulated parotid flow toConclusions: Stimulated flow measurements using Lashley cups, with a complication defined as flow