A Methodological Framework for the Cross-Culturaladaptation and Validation of Cancer Quality-of-Lifeinstruments in Nigeria: Lessons From Malaysia

Nigeria recorded about 152,000 new cancer cases and 91,000 cancer deaths in 2022, yet health-related quality of life is rarely measured in its three major languages where validated patient-reported outcome measures are few and mostly outside cancer care. This methodological review derives from a completed Malaysian programme a framework for adapting and validating the European Organisation for Research and Treatment of Cancer (EORTC) core questionnaire (QLQ-C30) and its disease-specific modules. All six publications of the author's programme (2012–2023) were included by design: a protocol with pilot data, four validation papers on the QLQ-C30 and colorectal module (QLQ-CR29) drawn from two samples, Bahasa Malaysia (n=93) and Chinese (n=96), and an applied study (n=324) whose participants may overlap with them. Extracted data were organised into seven pre-defined stages, mapped to EORTC translation guidance and COSMIN measurement standards and compared with African studies from a documented targeted search. The framework stages are instrument selection; EORTC-coordinated translation; piloting in 10–15 patients per language; at least 100 patients per language; interviewer-supported fieldwork; psychometric analysis, including factor and cross-language item analysis; and application. Three weak points recurred in both Malaysian languages: low reliability of the cognitive functioning scale (α=0.12–0.56), poor reliability of gastrointestinal scales in patients with a stoma (α=0.46–0.63), and misfit of the self-care item. The first also occurred in Uganda and Ethiopia. These may partly reflect instrument properties rather than translation failure and should be anticipated and examined. Nigeria can adapt an established method rather than develop one anew.