The UK Targeted Lung Health Check protocol recommends deferring lung cancer screening (LCS) for individuals who underwent a thoracic CT in the past 12 months. The impact of this recommendation is unquantified. Here, we report the prevalence and implications of recent thoracic CT in individuals undergoing LCS assessment in North-Central London.


Individuals with recent (in the preceding 12 months) thoracic CT were identified on direct questioning at Phone Screening (PS) and subsequent in-person Lung Health Check (LHC) assessment for LCS eligibility, or by reviewing patient records before LHC. CT reports were reviewed by a clinician to guide further management.


Of 2313 individuals assessed between 5/12/22 and 10/2/23, 120 (5.2%) reported having had a recent thoracic CT.On review, 22 (1.0%) of these had erroneously reported this information and proceeded with LCS. 98 (4.2%) individuals had LCS deferred as per the protocol. Of these, 69 (70.4%) and 29 (29.6%) were identified at PS and LHC respectively.

Findings relevant to screening (e.g., nodules) and incidental findings were identified on 61 of 98 (62.2%) CT reports. 9 individuals had findings requiring closure of the screening round (e.g., ongoing nodule follow up outside of screening). Re-invitation to screening was delayed by a median of 242 (IQR 121-348) days.


A significant minority of individuals undergoing LCS assessment had recent thoracic CTs, necessitating appropriate deferral of LCS and avoiding unnecessary radiation.

Local protocols should be implemented to proactively identify individuals with recent thoracic CT imaging to avoid inappropriate timing of LCS and ensure later re-invitation.