Scott Tomlins M.D. et al Show That Genetic Marker- PCA3 Based Urine Test is Effective In Early Detection of Prostate Cancer
A Recent study describes the discovery of a new urine test that can facilitate early detection of prostate cancer. Scott Tomlins et al from the University of Michigan Comprehensive Cancer Center and Michigan Center for Translational Pathology have found a new urine test, which when performed along with PSA screening can point out men with high risk of prostate cancer. This helps one to decide if there is need for a needle biopsy. The study has since been published in Science Translational Medicine.
At the molecular level, it is believed that a gene fusion – TMPRSS2:ERG causes prostate cancer. This is in reality a genetic anomaly where in two genes change places and fuse together to give rise to the gene fusion mentioned earlier. It has been observed that this genetic anomaly exists in 50% of all prostate cancers and is considered to be a confirmed indicator of presence of cancerous tissue in the prostate. However, due to the fact that only 50% prostate cancers show this marker, it was deemed necessary to include another marker – PCA3 for assurance. The combination of both markers – TMPRSS2:ERG and PCA3 was considered to be a better indicator of prostate cancer.
Aim of the Study
According to Scott Tomlins lead author of the study, the goal was to “develop a tool to help men with elevated PSA decide if they need a biopsy or if they can delay having a biopsy and follow their PSA and urine TMPRSS2:ERG and PCA3.”
Method used in the study
- 1,312 men with elevated PSA levels took part in the study.
- All these men had opted for either biopsy or prostectomy.
- Researchers tested urine samples for biomarkers for the product of the fused gene, TMPRSS2:ERG and PCA3.
- Based on the results, the men were grouped into low, intermediate, and high scores indicative of cancer risk.
- The results of urine tests were compared with biopsy results.
21% men in low score group, 43% men in intermediate group, and 69% men in high group had cancer according to their biopsies. Moreover, test scores of the urine test even correlated aggressiveness of the tumor based on the Gleason score and size of the tumor. 40% of men in high score group had aggressive tumors while only 7% of men in low score group had aggressive tumor.
The urine test can be considered as a tool to identify patients with high risk of prostate cancer. Senior study author Arul Chinnaiyan, M.D., Ph.D., says, “Many more men have elevated PSA than actually have cancer but it can be difficult to determine this without biopsy. This test will help in this regard. The hope is that this test could be an intermediate step before getting a biopsy”.
The new urine test with the genetic marker is not yet available as a screening tool. However, Gen-Probe Inc. has licensed the technology and is working in collaboration with The Michigan Center for Translational Pathology to offer the same to U-M patients within a year.