For years, the general practice used in the initial screening for prostate cancer is a blood test for prostate-specific antigen (PSA) in conjunction with a digital rectal examination. These tests are then used to determine whether or not to subject the patient to a prostate biopsy, inherent with its own side effects and hopefully negative results. If the biopsy reveals cancer, then the questions of whether or not to treat the cancer, what treatment(s) would be most effective while minimizing potential side effects, and the possibility of no treatment or “watchful waiting” must be addressed. It would be extremely useful if a blood or urine test could identify genetic biomarkers (genes and their products such as proteins) whereby physicians could determine not only the presence or absence of prostate cancer but be able to predict whether or not the cancer would require treatment and if so, should aggressive treatment be necessary. For the many cases of prostate cancer which are identified, ‘no one size of treatment fits all.’ Methods are sorely needed to determine the appropriate level of treatment, if any.
More than 25 genetic subtypes of prostate cancer have been already identified. Some of these cancers might never require treatment and a man could die of other causes while other cancers require immediate, aggressive treatment. A team of researchers from Seattle and Sweden have recently identified a set of variations in five (5) genes which may be signatures for lethal prostate cancer thereby requiring aggressive treatment. These genetic variants might serve as the basis for a new blood test that could be given on initial diagnosis in order to determine which patients need aggressive treatment versus “watchful waiting.” To discover the five “disease genes” implicated in lethal prostate cancers, researchers looked for genetic variants that prostate cancer patients share in common. These variants in genes are called single-nucleotide polymorphisms, or SNPs (pronounced “snips”). Genes can be depicted as chains of thousands of beads comprised of four-five basic colors all arranged in a specific sequence. An example of a SNP would be the substitution of one blue bead in a gene by a red bead at a specific location along the chain of thousands of colored beads. These inherited genetic variants are certain genes that may signal the development of fatal varieties of prostate cancer. The five SNPs that were identified were linked to five genes that may affect prostate cancer progression, namely LEPR, RNASEL, IL4, CRY1, and ARVCF. It was of special interest to note that two of the five genes studied (IL4 and RNASEL) were associated with inflammation of the prostate, thereby suggesting a possible link between chronic inflammation of the prostate and the triggering of prostate cancer. The state of this research requires much more validation and development before it could be used as a diagostic test for aggressive prostate cancer. But it is a significant finding and indicative of the type of biomarker which would eventually relieve the uncertainties associated with PSA tests.
The research findings were published in the September issue of Cancer Epidemiology, Biomarkers and Prevention, and summarized in the September 2011 issue of NewsPulse from the Prostate Cancer Foundation.