Dr Hiley is an Associate Professor with tenure in Radiation Oncology at University College London (UCL) and a Consultant Clinical Oncologist at University College London Hospital (UCLH). He is the UK Clinical Director for Lung Cancer for Genesiscare.

Dr Hiley specialises in the use of stereotactic radiotherapy (SBRT) for oligo metastatic and oligo progressive disease for various types of cancer, including but not limited to breast, prostate, colorectal, gynaecological, sarcoma, and lung cancers.

He is an expert in all non-surgical treatments for all types of lung cancer. His expertise encompasses chemotherapy, immunotherapy, and advanced radiotherapy techniques such as Volumetric Arc Therapy (VMAT), Intensity Modulated Radiotherapy (IMRT), Image Guided Radiotherapy (IGRT), Proton Therapy, and Stereotactic Radiotherapy (SBRT).

Dr Hiley also specialises in reirradiation, which involves the use of radiotherapy for patients who have previously received radiotherapy, particularly in the management of lung cancer and oligo metastatic and oligo progressive disease of various cancer types.

Appointed as a consultant in 2018, Dr Hiley is the clinical lead of the clinical oncology lung team at UCLH. He also serves as the UCLH Lead for Lung Proton Therapy, Deputy Lead of Clinical Trials for the CRUK Lung Cancer Centre of Excellence, NIHR Clinical Research Network Speciality Research Lead Radiotherapy for North London, and Deputy Chair of the National Cancer Research Institute Lung Group. Additionally, he heads a research group at the UCL Cancer Institute focused on understanding resistance to radiation therapy.

Dr Hiley is the Chief Investigator of the HIT-MESO study, which investigates the role of hemi-thoracic proton radiotherapy for mesothelioma. He is also the principal investigator and national chief investigator for several academic and commercial clinical trials in lung cancer. His research has been published in many of the world's leading journals, including NEJM, The Lancet, Nature, and Cell. Furthermore, he is a member of the expert group that authored the Radiotherapy for Lung Cancer Royal College of Radiologists Consensus Statement.