Nine-year Follow-up for a Study of Diffusion-weighted Magnetic Resonance Imaging in a Prospective Prostate Cancer Active Surveillance Cohort

Active Surveillance (AS) is a standardized care for localized postate cancer, and involves accurate selection of patients, as well as effective monitoring of patients. However, a small group of patients may develop a more advance disease while on AS; thus previous baseline investigations cannot fully explain this phenomenon. The use of MRI has been used to improve selection and monitoring of prostate cancer. There have been previous studies that looked at outcome data with median follow-up of 29 months for AS patients who underwent baseline DW-MRI, though no long term study has been conducted. This study’s aim is to determine long-term outcomes (9.5 years) of AS patients who underwent DW-MRI.

In total, 86 patients were used in this prospective AS study between 2002 and 2006. DW-MRI was performed according to a standard protocol, with mean ADC being calculated. Men underwent baseline DW-MRI in addition to standard sequences. To avoid influencing treatment decisions, DW-MRI sequence results were not available to the AS study investigations. For statistical analysis, a Kaplan-Meier analysis and univariate Cox regression were performed, and multivariate model incorporating selected baseline variables were fitted to the data.

The median follow-up was 9.5 years, while the median biopsy follow-up was 5.4 years. On univariate analysis, ADC below the median was associated with shorter TAH and TRT. Median TRT was 9.3 years for patients with ADC above the median and only 2.4 years for ADC below the median. For TRT, addition of ADC to a multivariate model of baseline variables resulted in a significant improvement in model fit. Receiver operating characteristics analysis for TRT revealed an area under the curve of 0.80.

In conclusion, 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 as an ongoing AS study for initial assessment, and as an alternative to repeat biopsy. The authors acknowledged some limitations of the study: small numbers that limited the number of variables used, and the study ideally requires a larger cohort. These scans may help in predicting whether patients should receive close monitoring or whether immediate treatment should be given. A future prospective cohort study of AS incorporating mpMRI will be later conduct to validate the DW-MRI approach.

Authors: Daniel R. Henderson, Nandita M. de Souza, Karen Thomas, Sophie F. Riches, Veronica A. Morgan, Syed A. Sohaib, David P. Dearnaley, Christopher C. Parker, Nicholas J. van As
Affiliations: Academic Urology Unit, Royal Marsden NHS Foundation Trust, London, UK; b Institute of Cancer Research, London, UK; c Department of Radiology, Royal Marsden NHS Foundation Trust, London, UK

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Reference:

European Association of Urology. Guidelines on prostate cancer. 2015. http://uroweb.org/guideline/prostate-cancer/

National Comprehensive Cancer Network. Clinical practice guidelines in oncology: prostate cancer. www.nccn.org/professionals/ physician_gls/pdf/prostate.pdf

van den Bergh RC, Ahmed HU, Bangma CH, Cooperberg MR, Villers A, Parker CC. Novel tools to improve patient selection and monitoring on active surveillance for low-risk prostate cancer: a systematic review. Eur Urol 2014;65:1023–31.

vanAsNJ, de SouzaNM, Riches SF, et al.A study of diffusion-weighted magnetic resonance imaging in men with untreated localised prostate cancer on active surveillance. Eur Urol 2009;56:981–8.

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