BackgroundBreast cancer-related lymphedema (BCRL) is one of the debilitating complications after breast cancer treatment. Several forms of patient-reported outcome measures (PROMs) were developed to evaluate the severity of BCRL based on the patients’ perspective. LYMPH-Q Upper Extremity Module is a newly developed questionnaire for BCRL. This study aimed to demonstrate the process of translation and cultural adaption from English to Mandarin Chinese. Methods and resultsThe translation process followed the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) best-practice guidelines for the translation and cultural adaption of PROM. The process included four steps: forward translation, back translation, back translation review, and patient interviews. In total, five patients with BCRL were recruited for patient interviews.The forward translation step involved two professional translators whose native language was Mandarin Chinese. A reconciled translated version was produced. In the back translation step, the reconciled translated version in Mandarin Chinese was sent to another professional translator whose native language was English. The back-translated version in English was sent back to the developer of LYMPH-Q for review. In this step, 22 items were revised. In the final step of patient interviews, 15 items were revised based on the patients’ feedback. ConclusionThe development of Mandarin Chinese version of LYMPH-Q Upper Extremity Module and its utilization in conjunction with the existing objective measures could provide a more well-rounded picture of the status of patients with BCRL worldwide.