To screen or not to screen?



By Harriet Gallegos, MRes Biochemistry

Harriet Gallegos sheds light on the result of prostate cancer screening trials.

With over 11,000 men dying from prostate cancer in the UK every year, it would be reasonable to assume that the introduction of a screening test allowing early detection of the disease would offer a life-saving tool. However, the PSA test appears to be coming up short according to results from a trial funded by Cancer Research UK at the University of Bristol.

Scientist with a Petri dish
Photo by Drew Hays / Unsplash

The PSA test measures the level of prostate-specific antigen (PSA) in the blood. This is a protein which is produced by both normal and cancer cells in the prostate. It’s typical to have a small amount of PSA in the blood but a raised level may indicate prostate cancer. The test sounds like an ideal diagnostic assessment for the disease but the CAP trial highlighted major floors with the technique. After an average of ten years follow up, the same percentage of men dying from prostate cancer was found in the screened versus the non-screened group – PSA screening did not lead to any additional lives saved.

The key issue with the test is that many men with raised PSA levels didn’t have prostate cancer whilst others with normal levels did have prostate cancer. Thus, some aggressive and lethal cancers could be missed when relying on the test alone. Additionally, the problem of over diagnosis occurs whereby clinically insignificant cancers that are unlikely to have spread or caused harm are detected, leading to unnecessary anxiety and side-effects of treatment.

Cancer Research UK is funding work that will follow the men for a further five years to determine whether there is any longer-term benefit on reducing prostate cancer deaths. For now, though the trial illustrates that more accurate tools to identify aggressive prostate cancers are required.

Featured Image:Marcelo Leal/ Unsplash

Want to hear about more Bristol research like this? Let us know your thoughts!