Tumor cell levels may predict survival in metastatic prostate cancer

Circulating tumor cell levels 3 to 5 weeks after the initiation of chemotherapy appear to predict overall survival in patients with metastatic androgen-independent prostate cancer, according to a prospective multicenter trial. Further, overall survival could be predicted at each of the tested time points.

The trial used the CellSearch Circulating Tumor Cell Kit (Immunicon Corp., Huntingdon Valley, PA), which was designed for longitudinal enumeration of circulating tumor cells in patients with metastatic androgen-independent prostate carcinomas prior to first- or second-line chemotherapy. A total of 276 patients were enrolled into the trial between October 2004 and February 2006 at 65 sites in the United States and Europe.

All patients had whole-body bone scans performed prior to the initiation of therapy. Those with measurable disease had CT scans of the abdomen and pelvis performed prior to initiation of therapy and at subsequent intervals, following institutional guidelines. PSA and circulating tumor cells were measured at baseline and at monthly intervals thereafter using CellTracks technology. Patients remained on the study and provided blood for up to 18 months or until documented evidence of disease progression or death was provided.

The blood test may enable doctors to respond more quickly to failing therapies, according to Immunicon.