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Focal Ablation Targeted to the Index Lesion in Multifocal Localised Prostate Cancer: a Prospective Development Study

European Urology [Epub ahead of print]

Abstract

Background

Although localised prostate cancer is multifocal in most instances, the index lesion might be responsible for disease progression.

Objective

To determine the early genitourinary functional and cancer control outcomes of index lesion ablation.

Design, setting, and participants

This was a single-centre prospective development study in which 56 men were treated (July 2009–January 2011). The mean age was 63.9 yr (standard deviation 5.8) and median prostate-specific antigen (PSA) was 7.4 ng/ml (interquartile range [IQR] 5.6–9.5). There were seven (12.5%) low-risk, 47 (83.9%) intermediate-risk, and two (3.6%) high-risk cancers.

Intervention

Multiparametric magnetic resonance imaging (mpMRI) and prostate biopsies to localise disease, followed by index lesion ablation using high-intensity focused ultrasound.

Outcome measurements and statistical analysis

Primary outcomes were genitourinary side effects measured using validated questionnaires. Secondary outcomes included absence of clinically significant disease at 12 mo.

Results and limitations

The composite of leak-free, pad-free continence, and erections sufficient for penetration decreased from a baseline frequency of 40/56 (71.4%) to 33/56 (58.9%) at 12 mo. Pad-free and leak-free, pad-free continence was preserved in 48/52 (92.3%) and 46/50 (92.0%) patients, respectively. Erections sufficient for intercourse were preserved in 30/39 (76.9%) patients. The median PSA nadir decreased to 2.4 ng/ml (IQR 1.6–4.1). At 12 mo, 42/52 (80.8%) patients had histological absence of clinically significant cancer and 85.7% (48/56) had no measurable prostate cancer (biopsy and/or mpMRI). Two (3.6%) patients had clinically significant disease in untreated areas not detected at baseline. The main study limitation is the short follow-up duration.

Conclusions

Index lesion ablation had low rates of genitourinary side effects and acceptable short-term absence of clinically significant cancer. Comparative effectiveness trials are required to assess cancer control outcomes against radical therapy.

Patient summary

In this study we looked at whether it is possible to treat the largest and highest-grade tumour in men who have more than one known prostate tumour. We show that the side effects of targeted ablation were low, with acceptable rates of early cancer control. Larger studies with longer follow-up are needed.

Trial registration

NCT00988130

Take Home Message

Although localised prostate cancer is multifocal in most instances, the largest lesion with the highest grade, the so-called index lesion, might be responsible for disease progression. In this first study to evaluate ablative therapy targeted to the index lesion alone, side effects were low and acceptable rates of early cancer control were achieved. If verified in larger studies with longer follow-up, this strategy might address the treatment-related harms inherent in current radical therapies.

Keywords: Focal therapy, Multiparametric magnetic resonance imaging, Index lesion, Transperineal template biopsy, Prostate cancer, Clinically significant.

Footnotes

a Division of Surgery and Interventional Science, University College London, London, UK

b Department of Urology, University College London Hospitals NHS Foundation Trust, London, UK

c Department of Health Services Research and Policy, The London School of Hygiene and Tropical Medicine, London, UK

d Clinical Effectiveness Unit, Royal College of Surgeons of England, London, UK

e Department of Urology, Hampshire Hospitals NHS Foundation Trust, Basingstoke, UK

f Department of Histopathology, University College London Hospitals NHS Foundation Trust, London, UK

g Department of Radiology, University College London Hospitals NHS Foundation Trust, London, UK

lowast Corresponding author. Division of Surgery and Interventional Sciences, University College London, 67 Riding House Street, London W1P 7NN, UK. Tel. +44 20 34479194; Fax: +44 20 34479303.

These authors contributed equally.