Validation of the EORTC QLQ-C30 and the FACT-G for assessing health-related quality of life among adult cancer patients in Cameroon.

OBJECTIVES

This study aimed to evaluate the psychometric properties of the French and English versions of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ -C30) and Functional Assessment of Cancer Therapy-General (FACT -G) among adults with cancer in Cameroon.

METHODS

We conducted a secondary analysis of a hospital-based, multicenter cross-sectional study carried out between December 2024 and August 2025 at three public oncology centers in Yaoundé. Adults with a confirmed cancer diagnosis completed a questionnaire package that included the EORTC QLQ-C30 and FACT-G. We assessed content validity, floor and ceiling effects, internal consistency, construct validity, measurement invariance across language groups, convergent and discriminant validity, and concurrent criterion validity. Sensitivity analyses were performed by re-estimating FACT-G models after excluding misfitting items.

RESULTS

Data from 507 participants were analyzed. Both instruments showed good content validity and excellent overall internal consistency. The EORTC QLQ-C30 had a well-supported factor structure and full measurement invariance across language groups, although several subscales and items showed pronounced floor and ceiling effects. The FACT-G showed poor structural fit, driven largely by low-loading items, particularly in the social/family well-being subscale. Excluding all problematic items improved confirmatory factor analysis fit and yielded satisfactory cross-language invariance for a modified FACT-G. Concurrent criterion validity was moderate to strong overall.

CONCLUSION

For health-related quality-of-life assessment in Cameroonian oncology settings, the EORTC QLQ-C30 should be preferred over the FACT-G, despite substantial floor and ceiling effects that warrant caution when interpreting responsiveness and sensitivity to change. Future studies should extend the measurement range of the EORTC QLQ-C30, strengthen the conceptual equivalence of the FACT-G, and assess longitudinal validity in this setting.