When we make treatment decisions we never know how effective the treatment will actually be for each individual and for how long that treatment effect might last. This makes all of our treatment decisions guess work.

A recent study has demonstrated that counting circulating tumor cells in the blood can be used to predict prostate specific antigen (PSA) failure in men with metastatic prostate cancer prior to receiving hormone therapy (ADT).

Researchers at the Department of Urology, The University of Kyorin, Mitaka, Tokyo, Japan enumerated the number of circulating tumor cells using the CellSearch System (trade mark) in whole blood. They took blood samples from 80 survivors with metastatic prostate cancer before they began ADT. The number of circulating tumor cells were then assessed every 3 months.

The number of circulating tumor cells found ranged from 0 to 222 per 7.5 ml blood (mean 17 +/- 31, median 14). A threshold of 5 or more circulating tumor cells per 7.5 ml blood was used to evaluate the ability of circulating tumor cells to predict androgen deprivation responsiveness.

Of the 80 patients 44 (55%) had 5 or more circulating tumor cells with a median androgen deprivation responsiveness of 17 months compared to more than 32 months for those with fewer than 5 circulating tumor cells (p = 0.007).

The number of circulating tumor cells, along with PSA values and Gleason score were significant parameters which were highly predictive of ADT responsiveness.

It would also be interesting to replicate this type of study on the blood serum of survivors who have been on intermittent ADT to see if the number of circulating tumor cells are predictive of the response we might experience when returning to ADT. If it is also predictive in these situations we can evaluate circulating tumor cells can help guide decisions about when going intermittent might or might not be a good coure of action when making treatment decisions.

J Urol. 2008 Aug 14. Epub ahead of print.

PubMed Abstract

Joel T Nowak MA, MSW