Researchers have managed to uncover the whole genetic sequence in prostate cancer. This complete map, hope researchers, will eventually lead to the development of more targeted drugs and a better understanding of which prostate cancers are likely to spread, one of the biggest challenges for physicians and patients.
Lead study author Michael Berger, now an assistant professor of pathology at Memorial Sloan-Kettering Cancer Center in New York City said, “With additional studies and as we sequence more prostate cancer genomes, we may be able to distinguish benign from more aggressive prostate cancers and prevent unnecessary surgeries and treatments.”
They looked at more than 20,000 genes and other DNA material surrounding the genes, for seven patients with advanced disease. The researchers then compared the cancer genome in the tumors to the normal genome in white blood cells taken from the same patients. They noted variations some of which had previously been identified and others that had never been seen before. The sequencing revealed nearly 100 such rearrangements and modification in each patient, said Berger. He added, “We are doing whole genome sequencing as opposed to more targeted sequencing because it’s really necessary to identify these rearrangements which are so important in prostate cancer.”
The study was conducted by researchers from the Broad Institute, Dana-Farber Cancer Institute and Weill Cornell Medical College, appears in the Feb. 10 issue of Nature.
Prostate cancer is the most prevalent cancer among British men, affecting a third of men over the age of 50 and accounting for about 10,000 deaths every year in England and Wales. It is second only to lung cancer in terms of cancer deaths. Prostate cancer killed an estimated 258,000 men around the world in 2008 and is the second most common cause of cancer death in men in the United States.
According to Dr Kate Holmes, the Prostate Cancer Charity's Research Manager, “This is one of the first studies to examine the sequence and structure of the genetic code as a whole, rather than one or more single genes alone… This has allowed the researchers to identify specific patterns where large disruptions in the structure of the genetic code have taken place… These disruptions can rearrange the way genes fit together and the way they function, which is often associated with the development of aggressive prostate cancer…This is interesting research that highlights a new approach to understanding the way prostate cancer develops. However, only 14 tissue biopsy samples were analyzed in total. The next stage will be to repeat the study on a much larger scale, which will be an extensive piece of work.”
This Wednesday further development in this direction was reported. Researchers noted that the genetic pattern could predict how aggressive prostate cancer is, potentially saving many men with less threatening tumors from undergoing unnecessary and life changing surgery.
British researchers found that men with the highest levels of “cell cycle progression” (CCP) genes, ones that encourage cells to grow, were three times more likely than those with the lowest levels to have a fatal form of prostate cancer. The findings were reported in the Lancet Oncology journal.
Researchers write that in patients who had already had surgery to remove their prostate, those with the highest CCP levels were 70 percent more likely to have a recurrence of the disease. Jack Cuzick, a cancer specialist based at Queen Mary, University of London said, “Our findings have great potential… CCP genes are expressed at higher levels in actively growing cells, so we could be indirectly measuring the growth rate and inherent aggressiveness of the tumor through a test.”
Based on this Myriad Genetics in the United States, has developed a test called Prolaris which measures CCP levels and Cuzick said that if further trials confirm his results, doctors could be using it in prostate cancer patients within a year.
This study involved 703 men with prostate cancer. Of these 366 men in America who had undergone surgery to remove the prostate, and 337 men in Britain with cancer that was confined to the prostate and were judged to not need immediate treatment. Tissue samples from the prostate were either taken during surgery or from the biopsy used to diagnose the disease.
Each sample was tested for 31 different genes involved in CCP and scientists found that specific combination of these gene levels can identify men at high or low risk of the disease spreading beyond the prostate and those most likely to die.
Helen Rippon, head of research management, at the British Prostate Cancer Charity, said in a statement the technology must be “comprehensively trialled in large numbers of men before it can be introduced into routine clinical practice.”
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