Urine-based test for a protein called MSMB

If you just read the media reports (for example, from Reuters, from the BBC or from The Daily Telegraph) you might get the idea that a new urine-based test for a protein called MSMB is vastly better at detecting prostate cancer than the PSA test. Sorry, but that is not actually the case at all.
To get an accurate understanding, you need to look at the full text of the actual article by Whitaker et al. in the on-line journal PLoS One.

What Ms. Whitaker and her colleagues have shown is that in men who carry a specific gene (the risk allele rs10993994), a protein known as microseminoprotein-β (MSMB) is significantly less likely to be found in the urine of men who have prostate cancer (or prostate intraepithelial neoplasia [PIN]) than it is in men with only benign prostate tissue. We already knew that the presence of rs10993994 is associated with increased risk for prostate cancer.

Whitaker et al. also were able to show that testing for MSMB in urine is a better indicator for prostate cancer risk than testing for prostate-specific antigen (PSA) in urine, but it is not better than testing for PSA in serum (the normal method of testing for PSA). And there is some evidence that the concentration of MSMB in urine may be associated with the Gleason score of a cancer in an individual patient who expresses the rs10993994 risk allele.

It is also important to understand, however, that Kader et al. have already shown that once prostate cancer tumors have developed, expression of rs10993994 has little effect on disease progression. The implication is that any increase in risk associated with expression of rs10993994 and MSMB affects the benign prostate gland and only the initial stages of tumor development

Let us be very clear. This is an interesting scientific finding. It demonstrates that there is the potential to link genetic signals of risk for prostate cancer to clinical signals of risk (expression or non-expression of a specific protein). It would also allow us to combine data on the presence/absence of MSMB in urine with data from other tests to assess risk for prostate cancer in particular individuals. Most specifically, it would theoretically help to be able to identify a subset of men who are at risk for prostate cancer long before there might be any evidence of disease based on a biopsy. However, even if everything were to go well, it may take 5 or more years to gain regulatory approval for such a test, and we would need additional information about it’s accuracy. Some initial testing on actual patients has already been initiated at one of the major UK prostate cancer clinical research centers.

Link to above article:

Is MSMB the next great thing in prostate cancer testing?


and from the UK Prostate Cancer Charity:

The Prostate Cancer Charity comments on new research into the MSMB protein as a potential marker for prostate cancer

The Prostate Cancer Charity comments on new research published in PLoS ONE, which suggests that microseminoprotein-beta (MSMB), a common protein found in semen, could provide an indication of a man’s risk of developing prostate cancer.

Dr Kate Holmes, Research Manager at The Prostate Cancer Charity, explains: “These preliminary results show that MSMB, a protein produced by the prostate gland, is found at significantly lower levels in the urine of men diagnosed with prostate cancer than those without the disease. The study also found that men with an aggressive tumour were also likely to have lower levels of the protein in their urine.”

She continued: “The study suggests that measuring levels of this protein could potentially be a powerful way to predict how likely a man is to develop prostate cancer. However, further research on a much larger scale is needed to determine how effective the detection of MSMB in the urine is for predicting the risk of, and potentially even diagnosing, prostate cancer.

“Given the known limitations of the PSA blood test, finding a technique to accurately diagnose prostate cancer is the Holy Grail of research into the disease, which is why these results are potentially exciting. More needs to be understood about MSMB, such as whether it is linked to non-cancerous prostate diseases. Once we have more information, we can better evaluate whether detecting levels of MSMB has a useful role in diagnosing prostate cancer. An accurate, reliable urine test for prostate cancer would be an invaluable tool if it is proven to be successful on a large scale.”