Abstract
Screening for prostate cancer using prostate specific antigen (PSA) remains a controversial issue. A raised PSA is not specific to cancer and treatments for prostate cancer are problematic and of debatable efficacy. In the UK, screening is not currently recommended, the high public demand for PSA testing being addressed by an informed choice programme, Prostate Cancer Risk Management, which aims to provide clear and balanced information and counselling to men over 50. Men younger than 50 are usually offered the test only if they have a family history or are of African ethnicity. However, a number of studies have found that increased PSA in the fourth decade correlated with an increased risk of prostate cancer.
In this prospective cohort study, the uptake of PSA testing within the context of a clinical trial in unselected men aged 45–49 was 34% and the prevalence of prostate cancer was 2.3%, with five of the 10 cancers classified as potentially clinically significant. Using a relatively low cut-off of 1.5 pg/L, 12.5% of participants had a raised PSA and were invited to have a biopsy, a repeat PSA test and a digital rectal examination. The prevalence of disease in participants with a raised PSA was 21.3%. The five cases of clinically significant prostate cancer were eligible for randomization to radical radiotherapy, radical surgery or watchful waiting and followed up for two years. No further increase in PSA was seen in any of the 10 cases.
They could not fully determine the performance of PSA testing or the prevalence of prostate cancer in the population, because biopsy was not offered to all participants. Lane et al. adopted a cut-off of 1.5 pg/L based on a previous paper, but they do not specify what PSA method they used. A quick glance at a UKNEQAS return for PSA shows a small but significant range of results even within a given method, highlighting the inappropriateness of absolute cut-offs. However, this paper does show that using a cut-off of 1.5 pg/L results in a comparable detection rate to those currently used in older populations. Lane et al. performed systematic 10-core biopsies, compared to the standard 6-core which would improve cancer detection. While this is laudable, it makes it hard to compare results with other studies and may increase discomfort and risk of infection.
There are large several large trials currently ongoing which should provide much needed evidence on both screening and treatment. If screening were introduced, this paper will provide evidence to inform the debate about age limits and PSA cut-off values.