Problems in assessing the response to therapy on bone metastases in breast cancer: analysis of post-recurrence prognostic factors

The problems of assessment of response to therapy and the factors contributing to the post-recurrence survival period were clinically investigated using 72 patients mostly with evaluable bone metastases. When the various factors involved in the post-recurrence survival period were investigated by Cox multivariate analysis, the results were significant for number of metastatic lymph nodes at initial surgery (p < 0.05) and disease-free period (p < 0.01), while the therapeutic effect on bone metastases made only a marginal contribution (p = 0.06). Imaging of bone metastases required a long time until effects could be assessed, 4 months (1-20 months) for Partial Response (PR) cases and 10 months (2-60 months) for Progressive Disease (PD) cases, with a median of 8 months, but even so, assessment of effect based on imaging techniques did not necessarily correlate with the clinical course. No background factors or therapeutic modalities typical for responders were noted. These findings require a comprehensive assessment of therapeutic utility for bone metastases by considering (a) the improvement of clinical symptoms (b) the decrease in tumor markers, and (c) the absence of new lesions.