A registry to audit the current range of applications, technical success rate, safety profile, complication rate and efficacy of cryoablation procedures being performed in children.

Cryoablation involves image-guided insertion of single-use specialised needles or probes through the skin into a soft tissue or bone lesion. A mechanised unit is connected to the probe(s) and generates cyclical freezing and thawing of the tissues at the probe tip(s) via exchange of highly pressurised gases through the probe lumen(s), utilising the Joules-Thomson effect. Extreme freezing and thawing of the lesion causes permanent tissue destruction through both mechanical disruption of tissue membranes and a secondary immune response effect.

Cryoablation is one of several minimally invasive ablative techniques used to reduce the size of or to eradicate soft tissue and bone lesions. Ablative techniques are now an accepted standard of care for many benign and malignant lesions in adult practice. Cryoablation is widely used in the management of renal cell carcinoma, with medium-term outcomes matching surgical resection.

The advantages of cryoablation over surgery, particularly in a paediatric population, are:

• Minimally invasive approach, therefore suitable for day case procedures and almost scarless
• Significantly faster recovery times compared to complex surgical debulking
• Minimal complication rates compared to surgery (less risk to nerves, blood vessels and critical solid organ)
• Affords excellent pain relief (has an independent role in chronic pain management)

To date the use of cryoablation in children remains novel and under reported.

The purpose of this registry is to audit the current range of applications, technical success rate, safety profile, complication rate and efficacy of cryoablation procedures in children. This registry would, as a minimum, clarify current practice and outcomes within individual centres, allowing teams to audit and benchmark their own procedures and aiming to align practice amongst individual hospitals. A registry would aim to generate a body of evidence to establish parameters for best practice and may highlight conditions that respond better or worse than others to this novel therapy. The audit may lead to a clinical trial for the treatment of one or more specific conditions but in the interim would provide evidence for the efficacy and safety of the procedure and will aim to protect against indiscriminate use of this treatment modality in children in the future.

Registry design: This is a prospective multi-centre, open, non-controlled repeat treatment registry and data collection in collaboration with individual hospitals in the UK and Europe.

The proposal is for a robust, multi-centre data collection system to support and establish the treatment pathway, safety parameters and outcomes of paediatric cryoablation. The number of procedures performed in each centre will be understandably small, given the specialist nature of this emerging modality and the small numbers of patients being offered this treatment. The registry aims to collect standardised data from all centres performing cryoablation in children to allow robust audit of this procedure. Multiple data sets will be collected and entered into an anonymised web based host.

Upon completion of recruitment and follow up, the data will be subject to uni-variate and multi-variate analysis.

The registry is designed with the patient at the centre of the data collection and outcomes. Anonymised data will be analysed collectively but will ultimately be owned and retained by individual trusts. Details of the full data set proposed are detailed in the attached study protocol.

Inclusion Criteria:

• all children in whom a clinical decision is made to treat with percutaneous cryoablation, to include those in whom cryoablation was not technically or clinically possible at any stage.

Exclusion Criteria:

• none

All children in whom a clinical decision is made to treat with percutaneous cryoablation

This is planned as a multi centre registry, as there are other IR centres within the UK and Europe that wish to contribute paediatric data. This would be welcomed, to increase numbers and strengthen the outcome data