Detection and clinical relevance of hematogenous tumor cell dissemination in patients with ductal carcinoma in situ

Hematogenous tumor cell dissemination is a crucial step in systemic disease progression and predicts reduced clinical outcome in breast cancer patients. Only invasive cancers are assumed to shed tumor cells into the bloodstream and infiltrate lymph nodes. However, recent studies revealed that disseminated tumor cells (DTCs) may be detected in bone marrow (BM) of patients with preinvasive lesions, i.e., ductal carcinoma in situ (DCIS). The purpose of this analysis was to examine the incidence and clinical value of DTC detection in a large series of patients with pure DCIS. 404 patients treated for DCIS at the University Hospital Tuebingen, Germany were included into this analysis. BM was analyzed by immunocytochemistry (pancytokeratin antibody A45-B/B3) using ACIS system (Chromavision) according to the ISHAGE evaluation criteria. Sentinel nodes were analyzed in 316 patients by step sectioning and hematoxylin-eosin staining. DTCs were detected in 63 of 404 patients (16%). No correlation was observed between BM status and tumor size, grading, histology or Van Nuys prognostic index. In two cases, metastatic spread into lymph nodes was observed; isolated tumor cells were found in one patient. After a median follow-up of 45 months (range 3-131 months), 3% of BM positive patients died compared to 1% of BM negative patients (p = 0.254). Relapse of any kind was observed in 7% of patients with DTCs vs. 5% of patients without DTCs (p = 0.644). The differences in overall (p = 0.088) and disease-free survival (p = 0.982) calculated by log-rank test were not statistically significant. Tumor cell dissemination may be detected in patients diagnosed with DCIS. Whether these cells disseminate from real preinvasive mammary lesions or represent the earliest step of microinvasion, remains unclear. A longer follow-up may be necessary to accurately assess clinical value of these cells in DCIS patients.