UK 2022 Consensus on Normal Tissue Dose-Volume Constraints for Oligometastatic, Primary Lung and Hepatocellular Carcinoma Stereotactic Ablative Radiotherapy.

The use of stereotactic ablative radiotherapy (SABR) in the UK has expanded over the past decade, in part as the result of several UK clinical trials and a recent NHS England Commissioning through Evaluation programme. A UK SABR Consortium consensus for normal tissue constraints for SABR was published in 2017, based on the existing literature at the time. The published literature regarding SABR has increased in volume over the past 5 years and multiple UK centres are currently working to develop new SABR services. A review and update of the previous consensus is therefore appropriate and timely. It is hoped that this document will provide a useful resource to facilitate safe and consistent SABR practice.

UK Consensus on Normal Tissue Dose Constraints for Stereotactic Radiotherapy.

Six UK studies investigating stereotactic ablative radiotherapy (SABR) are currently open. Many of these involve the treatment of oligometastatic disease at different locations in the body. Members of all the trial management groups collaborated to generate a consensus document on appropriate organ at risk dose constraints. Values from existing but older reviews were updated using data from current studies. It is hoped that this unified approach will facilitate standardised implementation of SABR across the UK and will allow meaningful toxicity comparisons between SABR studies and internationally.

Stereotactic body radiotherapy for liver metastases.

The role for local ablative therapies in the management paradigm of oligometastatic liver disease is increasing. The evidence base supporting the use of stereotactic body radiotherapy for liver metastases has expanded rapidly over the past decade, showing high rates of local control with low associated toxicity. This review summarises the evidence base to date, discussing optimal patient selection, challenges involved with treatment delivery and optimal dose and fractionation. The reported toxicity associated with liver stereotactic body radiotherapy is presented, together with possible pitfalls in interpreting the response to treatment using standard imaging modalities. Finally, potential avenues for future research in this area are highlighted.

The role of radiotherapy and chemoradiation in the management of primary liver tumours.

Due to advances in technical radiotherapy delivery over the past two decades there has been a rapid increase in the use of radiotherapy for intrahepatic malignancies. This overview provides a succinct summary of the current evidence for external beam radiotherapy in the management of primary liver tumours, highlighting areas for future research. Internationally, hepatocellular carcinoma is a leading cause of cancer death and UK incidence rates are rising rapidly. The main risk factor is chronic liver disease and, as a result, most patients will be unsuitable for curative surgical modalities of treatment. Conformal radiotherapy may be used in patients with localised disease who are unsuitable for alternative local therapies. It may also be used in patients with portal venous thrombosis or for palliation in advanced disease. Caution should be used in patients with pre-existent liver dysfunction (Childs Pugh B or C) due to increased rates of toxicity. Stereotactic body radiotherapy has been used for early stage disease, with promising long-term local control rates and a favourable toxicity profile. Stereotactic body radiotherapy has also been investigated as a 'bridge to transplant'. Charged particle therapy may be used for patients with more advanced liver dysfunction, or as a means of dose escalation, and warrants further investigation in early stage disease. Cholangiocarcinoma is a rare but aggressive primary liver malignancy in which only a minority of patients will be suitable for resection. Conformal radiotherapy and stereotactic body radiotherapy have been used in both the adjuvant and locally advanced settings, although small patient numbers and a lack of prospective trial data limit interpretation of their role. To fully define the role of radiotherapy in the management pathway for primary liver tumours, prospective randomised studies are required.