PROSTATE CANCER METASTASES ARE MONOCLONAL

NEW YORK (Reuters Health) Apr 23 - Most prostate cancer metastases, if not all, originate in a single primary cancer cell, according to a study by U.S. and Finnish researchers that was reported online on April 12 by Nature Medicine.

The study, which took more than 14 years to complete, centered on a genome-wide survey of both single nucleotide polymorphisms and copy number variations, which are deletions and duplications of large DNA segments. Both types of alterations of a cell's DNA are among the ways that cancer can begin.

The study was reportedly the first such high-resolution genomic overview of copy number changes in multiple metastatic cancers in individuals. These data enabled the researchers to conclude that "at least the vast majority of individuals with metastatic prostate cancer have cancers that originated in a single aberrant cell."

The report added that this finding is "likely to extend to other cancers."

Dr. G. Steven Bova of Johns Hopkins University School of Medicine told Reuters Health that a major challenge of this work was the "noise" created by separate subclonal changes in the cancer cells' copy number patterns. This was overcome in part, he explained, by the large number of cancer cell samples taken at autopsy from 30 men who had died of metastatic prostate cancer between 1995 and 2004. Bova estimated that he and his colleagues examined 30,000 blocks of tissue.

This study and others like it, Bova said, will bring "major clinical benefits." The idea that some day a patient who is diagnosed with cancer could receive a therapy tailored to the specific intricacies of his or her cancer is not a new one, he explained. What is new is that this study presents a model that could help that scenario become a reality.

Bova added that a very recent study came to a similar conclusion in lung cancer.

It has been established since at least the mid-1990s that primary prostate cancers are composed of multiple genetically distinct cancer cell clones. However, it has been controversial whether these primary prostate cancers typically produce metastases that are multiclonal or monoclonal.