Introduction/Background Although studies on performance in cancer patients are increasing, there has not been enough efforts to validate the Eastern Cooperative Oncology Group Performance Status (ECOG-PS). Therefore, we aimed to translate and validate the ECOG into Turkish.

Methodology This was done by drawing on the original version and by employing more rigorous translation methods to identify and resolve the translation problems. An expert panel was also employed to adjudicate on final translation and item selection issues. The ECOG questionnaire was validated between January and April 2019. Two bilinguals independently translated the English version of the ECOG questionnaire into Turkish, and then reconciled the forward translation of the Turkish version. The original ECOG was back-translated into English, then assessed for equivalence to the original. Gynecologic fellows interviews with 15 patients to test the interpretation of the translation were made, then modified and distributed to 114 patients for re-evaluation. A statistical analysis of inter-scale correlation, and test re-test consistency was performed with the Cronbach´s alpha coefficient. The changes from patient interviews were reflected in the final version.

Results In an intra-class correlation, the Cronbach´s alpha was high in all of the questions (0.81, P < 0.001). Test re-test Cronbach´s alpha analysis of reproducibility was higher than 0.75 for all of the 5 questions (P < 0.001).

Conclusion Translation and linguistic validation of Turkish version of the ECOG questionnaire was completed by a proper process, with high reliability and validity.

Disclosure Nothing to disclose