January 25, 2016 - Diffusion-weighted (DW)-MRI could be an alternative to biopsies when deciding if prostate cancer patients should receive treatment or continue with surveillance, a study has found. Scientists at The Institute of Cancer Research, London, used DW-MRI to evaluate patients with untreated prostate cancer, which they found could predict the aggressiveness of the disease and whether or not immediate treatment was required. The study, which was published in the journal European Urology,1 was funded by the NIHR Biomedical Research Centre at The Royal Marsden and the ICR.
As prostate cancer is often slow growing, suitable patients may be closely monitored through a system of active surveillance rather than being put on treatment. Biopsies are often used to select those who are suitable for active surveillance and for monitoring disease progression. The objective of the study was to determine long-term outcomes with respect to the apparent diffusion coefficient (ADC) derived from DW-MRI in a prospective AS cohort.
As an alternative to biopsies, the researchers used DW-MRI to measure the movement of water molecules within body tissues to determine the ADC of the prostate tissue. The male patients underwent baseline DW-MRI in addition to standard sequences. ADC was measured from the index lesion on T2-weighted images. To avoid influencing treatment decisions, DW-MRI sequence results were not available to the AS study investigators. Baseline ADC was analysed with respect to time to radical treatment (TRT) and time to adverse histology (TAH).
When the ADC score of prostate tissue was recorded in cancer patients over a period of 9.5 years, the researchers found that it was a useful indicator for predicting which cancers required treatment. The researchers concluded that long-term follow-up for this study provides strong evidence that ADC is a useful marker when selecting patients for AS. Routine DW-MRI is now being evaluated in our ongoing AS study for initial assessment and as an alternative to repeat biopsy.
Image: Axial Multiparametric MR Images. A) T2-weighted, B) diffusion weighted (DWI), C) apparent diffusion coefficient (ADC) and D) dynamic contrast enhanced (DCE) images of a patient with prostate cancer.2
This technique could be used in the future as a replacement for biopsies to better predict early on which patients should be selected for monitoring and which require treatment.
Professor David Dearnaley, Professor of Uro-Oncology at the ICR and a consultant at The Royal Marsden, said: “This long-term study has shown strong evidence that ADC is a useful marker when selecting patients to be put on active surveillance. We are continuing to evaluate the use of routine DW-MRI to assess whether this might be a suitable alternative to using repeated biopsies throughout surveillance.”
References:
1. Henderson DF, De Souza NM, Thomas K, et al. Nine-year Follow-up for a Study of Diffusion-weighted Magnetic Resonance Imaging in a Prospective Prostate Cancer Active Surveillance Cohort. European Urology. http://www.europeanurology.com/article/S0302-2838%2815%2900980-X/abstract/nine-year-follow-up-for-a-study-of-diffusion-weighted-magnetic-resonance-imaging-in-a-prospective-prostate-cancer-active-surveillance-cohort.
2. Miller JC. Multiparametric MR Imaging for Prostate Cancer. Radiology Rounds. http://www.mghradrounds.org/index.php?src=gendocs&ref=2010_august.
