Although prostate cancer is one of the most common types of cancer in men, it occurs most frequently after the age of fifty and many men who have the disease will eventually die of other causes without ever being diagnosed. Prostate cancer is most often discovered by prostate specific antibody (PSA) tests but, since relatively low levels of antibody are found in some men with prostate cancer and elevated levels can be found in other prostate conditions, the use of screening is controversial. Prostate cancers are, in most cases, slow-growing and the decision whether or not to treat a localised tumour is a trade-off between the expected beneficial and harmful effects of treatment in terms of patient survival and quality of life. In men who are being treated for prostate cancer, however, PSA is invaluable as a ‘tumour marker’ to assess response to therapy and monitor progression of the disease.
Two new biomarkers have recently been described which may improve the diagnosis of prostate cancer and – importantly – distinguish more aggressive forms of the disease so that patients can make more informed decisions about treatment.
The first study, by researchers at the University of Michigan Medical School and published in the February 12th issue of the journal Nature, showed that levels of sarcosine (N-methyl glycine) were elevated in the urine of men with prostate cancer, particularly those with more aggressive disease. In cell culture experiments, sarcosine was also found to help prostate cancer cells invade surrounding tissues. Along with sarcosine, levels of a number of other metabolites were found to be elevated dramatically during progression from benign tissue to localised cancer to metastatic disease. The team hopes that measuring levels of sarcosine alone, or with other metabolites, could provide a better indicator of likely disease progression.
The second study, described in the February issue of the journal Cancer Epidemiology, Biomarkers & Prevention shows that men with elevated levels of total – and particularly ionised – calcium in their blood have an increased risk of fatal prostate cancer.
The introduction of tests which give a better indication of which individuals will go on to develop an aggressive form of prostate cancer would allow men to make better informed decisions about when, or whether, to begin treatment.