Switching Breast Cancer Patients with Progressive Bone Metastases to Third-Generation Bisphosphonates: Measuring Impact Using the Functional Assessment of Cancer Therapy-Bone Pain

Because bone metastases cause significant pain, we developed a questionnaire to evaluate its nature, severity, and impact. This 16-item questionnaire is the Functional Assessment of Cancer Therapy-Bone Pain (FACT-BP). We also developed a 13/18-item questionnaire, the Functional Assessment of Chronic Illness Therapy-Treatment Satisfaction-Bone Treatment Convenience and Satisfaction Questionnaire (FACIT-TS-BTCSQ), to evaluate patients' expectations and acceptance of bone-specific therapies. We evaluated the performance of these scales in two clinical trials. In both trials, we enrolled patients with metastatic breast cancer, who had progressive bone metastases despite first-line therapy with pamidronate or clodronate. We administered intravenous zoledronic acid to 31 patients in one trial and oral ibandronate to 30 patients in the other. Patients completed the FACT-BP questionnaire and FACIT-TS-BTCSQ at baseline, then at Weeks 4, 8, and 12. The FACT-BP scale showed good internal consistency reliability [Cronbach's alpha (α) = 0.93–0.96]. There was evidence of construct validity, and known-group validity was supported by score shifts in the anticipated direction (Cohen's d effect size = 0.36). The FACT-BP score reflected clinical change as evidenced by differences in performance status. This cross-sectional anchor-based criterion suggested reasonable clinically important differences (effect size = 0.36). The FACIT-TS-BTCSQ showed good internal consistency reliability for treatment expectation (α = 0.87) and treatment experience (α's = 0.89–0.92). The FACT-BP scale is meaningful and appears appropriate for broader use. The assessment of satisfaction (FACIT-TS-BTCSQ) raised questions that will require further research.