Even though an agreed phenotypic definition of circulating tumor cells (CTCs) remains elusive in the literature, many current detection technologies isolate candidate cells based on molecular recognition of cellular epitopes that may not accurately predict CTC load. Rather than using such an epitope specific “positive-capture” strategy, we present a chip-based, centrifugal microfluidic platform integrating “negative-capture” magnetophoretic removal of normal white blood cells (WBCs) from a sample and subsequent, array-based enumeration of individualized, (untagged) abnormal cells. We compared the numerical recovery of cells on the array with the status of the donor patient, showing that the chip can has the potential to indicate the oncogenic severity of the blood donor.