Background and purpose: The International Breast Cancer Study Group (IBCSG) has developed and approach for assessing the impact of adjuvant therapy on quality of life (QL) within the framework of international, multilingual clinical trials. The major steps are summarized. Conceptual, methodological and practical issues are discussed with reference to results of two trials closed to accrual (IBCSG VI, VII) and one subsequent ongoing trial (IBCSG IX).
Patients and methods: QL was assessed in pre- and post-menopausal patients with operable breast cancer. Various single-item linear analogue self-assessment (LASA) scales were used as indicators of components of QL, including global indicators of well-being, functioning and health perception, and specific indicators of symptoms of disease and treatment. In trials VI and VII, QL was assessed at baseline, during adjuvant treatment and follow-up, and at recurrence. Based on this experience, the QL form was revised for subsequent trials and further investigated in a subsample of patients randomized into trial IX.
Results: In trials VI and VII, the QL indicators were responsive to the impact of biomedical factors at baseline, various adjuvant treatments, changes over the first 18 months, and recurrence. In trial IX, the revised QL form was well accepted by patients and staff. Completing this form did not exceed five minutes. QL differences between on and off cytotoxic treatment strengthen the claim that these measures are responsive. Correlations and logistic regression analyses show the expected relationship among the various global and specific indicators.
Conclusion: Results from two trials closed to accrual and an ongoing trial confirm the feasibility, validity and clinical relevance of the IBCSG approach for studying the impact of adjuvant breast cancer therapy on QL in international clinical trials.