We followed the EORTC translation manual [15], and the translation and adaptation process consisted of eight steps (Fig. 1).
Step 1: translation preparation
Before officially starting the translation work, we sought permission from the EORTC Translation Unit to translate the questionnaire. When the application was approved, we obtained the translation files, including an English version of the EORTC QLQ-LC29 questionnaire, a translation manual, and a translation review report containing an original English version and some previous EORTC translations from the EORTC Item Library (a database of EORTC questionnaire items and their translations).
Step 2: forward translations
Two native Chinese speakers (a thoracic surgeon and a thoracic nurse) with a good command of English independently translated the English version of the EORTC QLQ-LC29 into Chinese. Before translation, they received the English version of the EORTC QLQ-LC29 questionnaire and the file containing some existing translations from the EORTC Item Library.
Step 3: reconciled translation
A third native Chinese speaker (the translation coordinator) reconciled the two forward translations into a best single translation for each item and made comments on the reconciliation process. The methods and criteria used were adopted from the translation manual [15].
Step 4: back translations
Two PhD candidates (a native Chinese speaker studying in Sweden and an Egyptian studying in China) who are fluent in English independently translated the reconciled translated version into English. The two translators only received the reconciled translation and the instructions for back translation.
Step 5: back translation report
The translation coordinator sent the five above-mentioned translation files (two forward translations, one reconciled translation and two back translations) together with the comments from the translation coordinator to the EORTC Translation Unit for a comprehensive review. After several rounds of discussion with the EORTC Translation Unit, a consensus was reached. A preliminary translation was then prepared by the EORTC Translation Unit for proofreading.
Step 6: proofreading
The EORTC Translation Unit sent the preliminarily translated version of the EORTC QLQ-LC29 to a professional proofreader for review. The preliminary translation was compared with the original English questionnaire by the proofreader, who then prepared a report explaining all the changes and suggestions together, providing explanations of why they were needed. After all the questions had been discussed, and an agreement was reached between the translation coordinator and the proofreader, the Translation Unit prepared an interim translation for pilot testing.
Step 7: pilot testing
The pilot testing was conducted in a tertiary cancer hospital located in southwest China. Participants in the pilot test were required to be native speakers of the Chinese language, to have a histological diagnosis of lung cancer, to be undergoing active cancer therapy, and to be able to provide informed consent. According to the EORTC translation manual, 10–15 subjects are required for pilot testing [15]. We selected 10 patients of varying age, sex, education level, and annual income to maximise the representativeness of the patient sample. Patients first completed the EORTC QLQ-LC29 questionnaire, then a semi-structured interview using a predefined EORTC template (a patient response sheet) was conducted by a well-trained interviewing researcher. Each patient was asked if any item was difficult to answer, confusing, difficult to understand, or upsetting. If so, the patient was encouraged to rephrase the question using their own words. The interviewer also tested some alternative wordings to check if they could make the items more easily understood. A report containing the results of the pilot testing and relevant comments was then sent to the EORTC Translation Unit for review.
Step 8: finalisation
After several rounds of discussion, a consensus was reached between the translation coordinator and the EORTC Translation Unit. The Translation Unit approved the final translated version and closed the project.
Statistical analysis
Simple descriptive statistics were used, including the frequency and median (range) for age, sex, educational level, type of medical insurance, personal annual income, employment status, type of current treatment, and time interval between the date of the interview and the most recent treatment. Quantitative information was presented in tabular form.