The present study aimed to investigate the clinical relevance of minimal residual cancer in breast cancer patients before and after high-dose adjuvant chemotherapy with or without progenitor stem cell support.

One hundred and eighteen high-risk stage II breast cancer patients entering the Scandinavian Study Group multicentre trial [1] were randomised to nine cycles of dose-escalated FEC (5-flurouracil, epirubicin, cyclophosphamide) or three cycles of standard FEC followed by high-dose chemotherapy. Bone marrow (BM) samples at diagnosis and 6 months after completion of chemotherapy were assessed for the presence of cytokeratin-positive (CK+) cells. CK+ cells in BM were evaluated as a prognostic and predictive marker and were compared with other defined prognostic factors of the primary tumour.

Monitoring BM changes at time of diagnosis and at 6 months post-treatment is an independent predictive factor for breast cancer-specific survival (P = 0.001, univariate analysis). Those who have consistent CK-negative BM findings constitute a group of patients with good prognosis.

Monitoring of CK+ cells in BM before and after high-dose chemotherapy with or without stem cell support can be used clinically as a surrogate maker to predict outcome in breast cancer patients.