Angeles Montero, MD, PhD, Royal Brompton Hospital, London, UK, talks on the updated World Health organisation (WHO) classifications for thoracic cancer, highlighting challenges around the assessment of resection margins. Dr Montero gives an overview of the WHO classification system, including its role in lung cancer staging, and discusses recent updates such as the inclusion of resection margins for tumors which are not located in the bronchial or vascular lumen. This interview took place during the 19th British Thoracic Oncology Group (BTOG) Annual Conference 2021.