Correlation between changes in the tumour markers CA-M26 and CA-M29 and standard response evaluation in patients with metastatic breast cancer.

In this study we correlated response evaluated by standard WHO criteria to strict defined criteria of tumour marker response in 63 patients with metastatic breast cancer. Pretreatment sensitivity at first evaluation was 71% and 85% for CA-M26 and CA-M29, respectively. Of the 156 evaluations for CA-M26 and 178 for CA-M29 in 26 and 30 patients with evaluable lesions 72% and 67% were concordant with the results of the clinical evaluations. When the discordant evaluations due to lead time were included the concordances were 87% for CA-M26 and 83% for CA-M29. Of the 70 evaluations for CA-M26 and 92 for CA-M29 in 19 and 24 patients with non-evaluable lesions 59% and 72% were concordant with the results of the clinical evaluations. Most importantly, progressive disease according to the changes in the marker level nearly always predicted disease progression. Such knowledge obtained in a simple way may prevent continuation of ineffective treatment in patients with metastatic breast cancer.