Prostate cancer is perhaps the only cancer type in which biomarkers have changed the clinical course of the disease. As recently as 20 years ago, more than half of the men presenting with prostate cancer did so with metastatic disease. Today, this is a rarity. Despite this apparent success, we still are developing better markers for the disease. Prostate cancer is the second leading cause of cancer death in men in the USA. In 2007, the American Cancer Society estimates that there will be 218 890 new cases and 27 050 related deaths . A study by Sakr et al. revealed that by the age of 30–39 years, about 29% of men will have microscopic evidence of prostate cancer, which increases to about 65% by the age of 70 . Prostate cancer arises as a multistep process that includes chromosomal and gene expression modifications. This can lead to overgrowth of cells surrounding the prostate gland, inhibition of apoptosis of these cells, invasion and angiogenesis.
The specific cause of prostate cancer is still unidentified. Factors such as age, genetics, race, diet and lifestyle may contribute to a man’s risk of developing prostate cancer . The main risk factor for the disease is age. Prostate cancer is diagnosed typically after the age of 50 and the average age at diagnosis is 70 years . There is, however, a trend towards increasing diagnosis in younger men . Prostate cancer in its early stages presents without symptoms, usually through screening, but the diagnosis may also be made in men presenting with pain, difficulty in urinating, haematuria, painful urination and erectile dysfunction. It is often diagnosed incidentally following a routine medical assessment that identifies elevated serum prostate-specific antigen (PSA) and/or an abnormality on digital rectal examination (DRE). The patient presenting with an elevated PSA or abnormal DRE usually requires further investigation with a biopsy of the prostate to establish a histological diagnosis of cancer where malignancy is present.
Despite the widespread use of PSA testing, PSA is not considered an ideal tumour marker. It is estimated that about 25–35 million PSA tests will be performed in the USA every year . Approximately 1.6–1.8 million men proceed to prostate biopsy. Only about one in seven or one in eight of these men is diagnosed with prostate cancer. As a result, the number of men with elevated PSA levels and at least one set of negative biopsies is growing, with more than 25 million men now in this situation in the USA. The availability of PSA has certainly not adequately served all those men tested throughout the world.
Initially, a cut-off point of 4.0 ng/ml was established as the upper limit of normal for serum PSA . Using this cut-off, PSA testing was combined with DRE for prostate cancer detection. Nevertheless, over the last 20 ...