Validation study of the Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 for patients with testicular cancer

Objective: To validate the Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 in Japanese-speaking testicular cancer survivors.

Methods: A total of 200 testicular cancer survivors were recruited at eight high-volume institutions in Japan. The participants completed the Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26, the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 and the International Index of Erectile Function 15 questionnaires. A total of 40 participants completed a retest of the questionnaires 2 weeks after the first response. The psychometric properties of the Japanese version including test-retest reliability, internal consistency and concurrent validity were evaluated.

Results: The mean age at response was 43 years (range 22-74 years), and the mean period after treatment was 77 months (range 0-416 months). The response rate for each item, except sexual function, was high, and the percentage of missing values was less than 3.5%. For test-retest reliability, seven of 12 scales met the criteria (intraclass correlation 0.70-0.86). For internal consistency, four of seven scales met the criteria (Cronbach's alpha 0.62-0.91). For concurrent validity, treatment side effects of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 were related to some domains of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30. The sex-related subscales of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 were moderately correlated with some International Index of Erectile Function 15 domains.

Conclusions: The psychometric properties of the Japanese version are equivalent to the properties of the original European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26. The Japanese version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 questionnaire is a useful tool to assess the health-related quality of life of testicular cancer patients.