P165 The ‘suspicious’ chest X-ray. How good are we at distinguishing high risk from low risk abnormalities?

IntroductionWe have developed two parallel direct recall CT pathways for patients with abnormal CXRs – a CX3 (NOLCP) pathway where CXR is suspicious for lung cancer, and a CX2 (urgent but non 2ww) pathway where suspicion is low but CT confirmation is warranted. Normal and benign abnormalities are categorised as CX1. We looked at the types of CXR findings reported as suspicious vs low suspicion for cancer and the rates of cancer diagnosis within each pathway to assess how well radiologists were able to identify suspicious lesions.MethodsUsing electronic records, patients that had a direct recall CT following primary care requested CXR from May 2018 – May 2019 were cross-referenced with our local cancer databases. Cancer diagnosis until May 2020 were recorded, such that all patients had 12–24 months of follow up following CXR. A respiratory lung cancer physician then subdivided CXR reports into broad categories of abnormalities and the incidence of cancer within each group was determined.Results622 abnormal CXRs were reported as low suspicion for cancer (CX2) and in this group 43 (6.9%) were diagnosed with cancer. 219 CXRs were reported as suspicious for cancer (CX3) and this was confirmed in 98 (44.7%). Results are summarised in table 1. Radiologists were good at distinguishing high risk from low risk abnormalities in the following categories: defined nodule/mass (cancer rate 60.8% vs 6.5%), collapse/atelectasis (85.7% vs 2.9%), hilar (29% vs 3%) and mediastinum (100% vs 5%) but were less able to distinguish between high and low risk pleural abnormalities (37.5% vs 27.6%) and other/unspecified peripheral opacities (22.6% vs 8.7%).Abstract P165 Table 1Summary of final diagnoses for the two direct recall CT pathways – CX2, CXR with low suspicion of cancer but CT correlation required and CX3, CXR with high suspicion of cancer. CX2 pathway (CXR low suspicion of cancer) CX3 pathway (suspicion of cancer) CXR abnormality Lung cancer Other cancer Non cancer % Cancer Lung cancer Other cancer Non cancer % Cancer Nodule/mass 2 1 43 6.5 54 5 38 60.8 Other/unspecified peripheral opacity (incl. consolidation) 17 7 252 8.7 9 3 41 22.6 Hilum 2 0 67 2.9 8 2 25 28.6 Effusion/pleural abnormality 6 2 21 27.6 5 4 15 37.5 Collapse/atelectasis 1 0 34 2.9 6 0 1 85.7 Artefact/normal variant 3 1 100 3.8 0 0 0 - Mediastinum/paratracheal 1 0 18 5.3 0 2 0 100.0 Normal but concerning symptoms 0 0 19 0.0 0 0 1 0.0 Elevated hemidiaphragm 0 0 8 0.0 0 0 0 - Inappropriate use of pathway (e.g