ISET Test

The ISET Test (Isolation by Size of Tumor cells / Trophoblastic cells) is a diagnostic blood test that detects circulating tumor cells in a blood sample. The test uses an in-vitro diagnostic system developed at INSERM, the Université Paris Descartes and Assistance Publique Hôpitaux de Paris (AP-HP) in order to isolate cancer cells from blood without loss and identify them through a diagnostic cytopathology-based approach.

A 1-ml sample of blood will typically contain 5 to 10 million leukocytes, 5 billion erythrocytes, and a small number of circulating rare cells, including:

The diagnostic problem is to find and identify the rare CTCs among the abundant other cells in a given blood sample.

The ISET technology is based on the observation that tumor cells of all types of solid cancers are larger than blood cells (leukocytes and erythrocytes). However, blood filtration to recover rare circulating tumor cells without loss and without cell damage is a challenge. The ISET test uses a specially designed device and specially designed filters to allow the elimination of all erythrocytes and most leukocytes from the sample, making the subsequent cytopathology process significantly easier and more accurate.

Because ISET relies on cytopathology (i.e. specific visual identification of cancer cells) rather than isolating cells by biomarkers, its developers claim that the test has a relatively low false-positive rate. They also claim a 95% sensitivity rate (in 95% of samples in which CTCs are present, the ISET test will isolate the CTCs sufficiently for cytopathological identification). Published results indicate that the test is more sensitive and specific than CellSearch, the present FDA-approved metastatic cancer screening method, for

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