Protein in prostate tissue ‘indicates increased cancer risk’
Researchers have discovered that men who have a specific protein present in prostate tissue biopsies may be at increased risk of developing prostate cancer. This is according to a study published in the Journal of Clinical Oncology.
The American Cancer Society estimates that around 238,590 new cases of prostate cancer will have been diagnosed in the US throughout 2013.
Current methods for diagnosing the cancer include blood tests for the protein prostate-specific antigen (PSA) and biopsies. But researchers from Weill Cornell Medical College, who conducted this most recent research, say that these methods do not always determine a patient’s chance of dying from the cancer.
By looking at certain changes within prostate cells from initial biopsies, the investigators wanted to see if they could determine which men are at higher risk of prostate cancer, and whether they need further biopsies or other monitoring methods.
ERG expression linked to invasive prostate cancer
It was found that 53% of men whose biopsies showed expression of a protein called ERG went on to develop invasive prostate cancer, compared with 35% of men who showed no ERG expression.
The prostate cancer-specific ERG protein was co-discovered in 2005 by Dr. Mark Rubin, the Homer T. Hirst professor of oncology in pathology and professor of pathology and laboratory medicine at Weill Cornell Medical College.
The overproduction of the protein results from the fusion of two genes that lead to a chimeric gene known as TMPRSS2-ERG. This is present in more than half of prostate cancers diagnosed in the US every year, according to the researchers.
Since all of the biopsies analyzed in the study were classified as having high-grade prostatic intraepithelial neoplasia (HGPIN) present (tumors that could become cancerous), the researchers say men with ERG-positive HGPIN biopsies could benefit from early treatment of prostate cancer and closer monitoring.
Furthermore, they note that men with ERG-negative HGPIN biopsies could avoid future biopsies, as they may be unnecessary.
Commenting on the findings, Dr. Rubin says:
“What this study shows is that not all HGPIN is equal – that is, clinically significant. When confirmed in larger studies, testing for ERG in these precancerous lesions may change clinical practice in how men are evaluated with abnormal biopsies and may lead to earlier cancer detection.”
Development of prostate cancer ‘increases over time’
The researchers wanted to determine whether the ERG protein present in biopsies may be a potential marker of future prostate cancer.
They analyzed ERG protein expression from HGPIN-positive biopsies of 461 men who were enrolled in the study. ERG expression was found in 11% of the biopsies.
The investigators then monitored the patients who had ERG expression in their biopsies for a period of 3 years.
From this, it was found that the number of patients who developed invasive prostate cancer increased over time. Within the first year, 15% of patients developed the disease. This increased to 37% in the second year and 53% in the third year.
Dr. Rubin says there are already ERG tests available that can detect the protein in tissue and urine, and that this study, among others, emphasizes the potential use of these tests.
“We are now in an era of precision medicine – where looking at cancers at a molecular level will give us crucial information that we can use to decide on the right clinical course for individual patients,” says Dr. Rubin.
“In that same light, findings in this study point to a potential advance in early assessment and treatment of prostate cancers.”