Dr Clark specialises in the non-surgical treatment of lung cancer, including chemotherapy, radiotherapy, targeted therapy and immunotherapy. He is also involved in a number of clinical trials and an ongoing Stratified Medicine Programme. He also treats mesothelioma and rarer thoracic tumours such as thymoma and adenoid cystic carcinoma.
Away from clinical practice, Dr Clark has been an active Fellow of the Royal College of Radiologists, as a member of the FRCR Part 2A Committee since 1999 and co-chair of this committee since 2014. He has also been an active member of the RCR Fellowship Examination Board and is developing a role in medical education for oncology trainees in the West of Scotland.