Assessment of four monoclonal antibodies as serum markers in breast cancer.

Four monoclonal-antibody-defined serum markers (CA15-3, HMFG1, HMFG2 and NCRC-11) were examined in five groups of subjects: controls, benign breast disease and stage I/II, stage III and metastatic breast cancer. None of the markers were significantly elevated in primary breast cancer (i.e. stage I/II or stage III) compared with controls or patients with benign breast disease. These markers therefore have no role in screening or in the diagnosis of primary breast cancer. CA15-3, HMFG2 and NCRC-11 were significantly increased in the patients with metastatic breast cancer (P less than 0.001), indicating a potential use in the diagnosis of symptomatic metastases. In patients with metastases, sequential changes in CA15-3 correlated significantly with clinical response to therapy. Thus CA15-3 is a powerful marker of response and in combination with other markers, may provide an objective measurement of response to therapy in patients with advanced breast cancer.