Delivering low-dose CT screening for lung cancer: a pragmatic approach

The BTS guidelines use nodule size and type, along with other criteria such as a nodule malignancy risk score (Brock score) and volume doubling time (VDT), to calculate appropriate follow-up management on a per-nodule basis. The SUMMIT algorithm follows this method closely, but was adapted in several key ways, including accommodation for a 3-year annual screening programme rather than a one-off CT chest; changes in the use of the Brock malignancy score; dispensing with VDT calculations in favour of a growth threshold of ≥25% to inform management at 3 months; a minimum size requirement (200 mm3) before referral to multidisciplinary team (MDT); and 12-month (vs 3-month) follow-up of pure ground glass lesions ≥5 mm. The complete SUMMIT Pulmonary Nodule Protocol is available in online supplementary figure S1. CAC is often detected on LDCT and the screening target demographic is at increased risk of CVD due to their smoking histories and ages; because of this, American LCS screening programmes are encouraged to report back CAC to screenees in order to instigate primary prevention, where appropriate.4 In the UK, however, instigation of appropriate management of CVD is based on the calculation of a QRISK2 score. From LSUT data, the vast majority (projected figure >90%) of the SUMMIT population are expected to have a QRISK2 score greater than 10%, the threshold for instigation of primary prevention.5 After consultation with cardiology and general practice colleagues, the study team elected to include a prompt in all letters to participants’ general practitioners (GPs) recommending assessment via QRISK2 score, an approach which avoids communicating a CAC score, which provides no additional prognostic information nor evidence base for intervention.