According to a prostrate cancer study published in The Lancet Oncology medical journal, counting the number of circulating tumor cells - CTCs - is a reliable method with which doctors can examine the progress of treatment in prostrate cancer patients.

Tracking prostrate cancer using the CellSearch test - prepared by Johnson & Johnson unit Veridex - by counting CTCs in the bloodstream has more consistent results than the presently-in-use blood marker. The test gives the doctors a much clearer picture of the patient's condition, pre-treatment and post-treatment.

CTC count helps review the development of the ailment, as well as check how well a patient is responding to chemotherapy.

The study, which observed 164 men suffering from prostrate cancer, found that CellSearch is a better method compared to a standard test that merely looks at PSA - prostate specific antigen - levels, which may shoot up when prostate tumor advances. Once chemotherapy is introduced, the standard tests leave the doctors struggling to track the treatment.

In the opinion of one of the researchers, Dr. Howard Scher of Memorial Sloan Kettering Cancer Center in New York, "CTC number can be used to monitor disease status. CTC counts can be used to help determine an individual's prognosis, particularly when the counts are high. And it also helps in terms of understanding if the treatment is working." (Harkiran contributed to this report)