[LINGUISTIC VALIDATION OF JAPANESE VERSION OF EUROPEAN ORGANIZATION FOR RESEARCH AND TREATMENT OF CANCER QUALITY OF LIFE QUESTIONNAIRE-TESTICULAR CANCER 26 (EORTC QLQ-TC26)].

(Purpose) To translate the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Testicular Cancer 26 (EORTC QLQ-TC26) into Japanese and evaluate the linguistic validation of the translated EORTC QLQ-TC26. (Methods) Developing the EORTC QLQ-TC26 Japanese was performed strictly according to the EORTC Quality of Life (QOL) Group Translation Procedure. The translation process consisted of 3 steps: forward translation by 2 urologists and reconciliation (single forward translation), backward translation by 2 native English speakers and comparison with source questionnaire (intermediate version), and pilot testing of the intermediate version in 10 patients with testicular cancer and reconciliation with EORTC QOL Group. (Results) After forward translation by 2 experienced Japanese urologists, any disagreements were resolved via a reconciliation process, resulting in a single provisional forward translation. This translation was back-translated by two independent backward-translators (fluent in both, Japanese and English) in order to ensure that the provisional forward translation was an adequate representation of the English original. Based on the discussion with EORTC QOL group, the intermediate version was developed. Each translated item was pilot-tested on 10 patients diagnosed with testicular cancer. Most patients experienced no difficulties in completing the questionnaire. On the basis of the interview and reconciliation with EORTC QOL Group, two items of the provisional translation required adaptation. (Conclusions) The EORTC QLQ-TC26 Japanese was developed in a linguistically valid manner. This can be used for cross-cultural assessment of health related QOL in men with testicular cancer.