The most common cancer in men after skin cancer is prostate cancer, but the screening tests are notoriously unreliable. A new test is not only reliable but simple and inexpensive. It may even be able to predict the cancer five years before treatments are needed.

Right now, a blood test measures the levels of prostate-specific antigen or PSA which is made by both normal and cancerous prostate cells. PSA values under four usually don't predict cancer. As the numbers go up, the chances of cancer being present go up as well. But up to three quarters of men with higher numbers don't have cancer after a biopsy.And fifteen percent of men with low PSAs do have it. Apparently, many factors affect PSA levels such as obesity, and even riding a bike!

The new test isn't so fickle. The Prostate Urine Risk test or PUR was developed using machine learning that looked at gene expression by measuring certain products in urine. Urine from about five hundred men was tested and the machine identified the expression of thirty five genes as markers for prostate cancer. It classifies patients into four groups: cancer-free, low risk, intermediate, and high risk.

PUR even predicted disease progression up to five years before current tests could. It also identified men who were eight times less likely to need treatment within five years of their diagnosis. This helps men decide when to start treatment.

Today's tests can't tell a man if he has cancer, low risk cancer or cancer that needs treatment. PUR may be available in three years which would be an amazing tool for the nearly two hundred thousand men diagnosed each year with prostate cancer.