Counting Tumor Cells In Blood Predicts Treatment Benefit In Prostate Cancer

[News]

Counting the number of tumor cells circulating in the bloodstream of patients with castration-resistant prostate cancer can accurately predict how well they are responding to treatment, new results show. Researchers showed that changes in the number of circulating tumor cells predicted the outcome after chemotherapy in this hard to treat cancer.

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[gpawelski]

It would be important to develop a method of in vivo labelling of tumor cells in the circulation and to monitor their trafficking and homing to other sites, such as the leptomeninges. If these cells are viable and therefore able to disseminate, I think the most robust test to this end is to document their ability to metastasize.

Tumor cell release in the circulation after cytotoxic chemotherapy is not new information, since it has been described about 15 years ago by E. Sphall in a paper published in Blood, where they measured tumor cell release in the circulation after stem cell mobilizing chemotherapy and G-CSF support.

What they found was strikingly important, as tumor cells mobilized from the bone marrow (if there was even minimal bone marrow infiltration) and the tumor (if their was residual disease in primary or metastases at the time of peripheral stem cell mobilization) had a temporarily different appearance in the peripheral blood, essentially yielding two distinct peaks; an early one mobilizing with the CD34+ PBPCs and the other released later, and thought to represent tumor-derived cells.

The outcome for metabolic responders and non-responders with circulating tumor cell (CTC) monitoring is basically what is going on with a functional profiling assay, showing what patients are benefiting from what drug agents before introducing them into the patient. Monitoring CTCs could be utilized for confirmation after the patient is administered assay-directed most beneficial therapeutic agents.