New scan will show exactly when prostate cancer becomes a killer

Published on Sunday 19 December 2010 17:29

AN ADVANCED type of body scan could help doctors decide when men with slow-growing prostate cancer need treatment, it was revealed yesterday.

Many men diagnosed with early prostate cancer that is not immediately life-threatening undergo "active surveillance".

Doctors monitor their condition with biopsies and blood tests and only start aggressive treatment if the tumour starts to grow more quickly.

But biopsies - the removal of tissue samples for analysis - are painful, invasive and carry sideeffects, while the standard PSA (prostate specific antigen) blood test can be inaccurate.

The new technique, using diffusion-weighted magnetic resonance imaging (MRI), provides a more patient-friendly and reliable method of monitoring prostate cancer, scientists believe.

In the pilot study, 50 patients were scanned at the time of their initial diagnosis and given another examination two years later.

Each scan was used to calculate a figure called "apparent diffusion coefficient", a measurement of water movement within tissue.

Previously, it had been shown that these measurements are significantly lower in men with high-risk prostate tumours.

By the time of their follow-up appointment, 17 of the men had required treatment while 33 remained under active surveillance.

The team found the diffusion-weighted readings fell between the two scans in men who progressed to treatment, but remained constant in those who did not.

Study leader Professor Nandita deSouza, from the Institute of Cancer Research, based in Sutton, Surrey, and London, said: "Diffusion-weighted MRI has a lot of potential for monitoring patients under active surveillance, as the scans clearly showed which men's cancers were progressing.

"If the technique continues to show promise in larger-scale studies, it could one day save men under active surveillance from the discomfort and potential complications of regular biopsies."

The findings were published in the British Journal of Radiology.

Recent figures show that the proportion of men opting for active surveillance rose from zero to 39 per cent between 2002 and 2006. Each year 35,000 men are diagnosed with prostate cancer and about 10,000 die from the disease.

Lesley Walker, from the charity Cancer Research UK, said yesterday: "It's important that we find better ways to distinguish prostate cancers that spread quickly and which could be fatal from those that may not even need treatment.

"Imaging like this has great potential to provide non- invasive, accurate ways to monitor patients to help doctors limit the number of men who undergo unnecessary treatment. "

She added: "It now needs to be confirmed in much larger studies before this test should be used routinely in a clinical setting."