The role of a dedicated chest x-ray reporting tool in the lung cancer diagnostic pathway

Background: The National Optimal Lung Cancer Pathway (NOLCP) aims to speed up to the time to diagnosis based on early chest x-ray (CXR) imaging and reflex escalation to computed tomography (CT) scanning (within 72 hours) of high risk CXRs. In our region, a dedicated CXR reporting tool has been introduced, which categorises patients’ CXRs as normal, abnormal of uncertain significance or highly suspicious for lung cancer. The aim of this study was to evaluate the sensitivity and specificity of the reporting tool for lung cancer diagnoses. Methods: Patients referred to two UK tertiary centres between 01/01/2017 and 31/12/2017 were included. Clinical history and outcomes were extracted from medical records. Results: 835 patients were referred. Of 349 (41.8%) patients with a highly suspicious CXR, 163 (19.5%) were diagnosed with cancer. 186 (22.3%) patients had a highly suspicious CXR and a non-malignant diagnosis, including infection, nodules and bronchiectasis. 93 patients (11.1%) had a normal CXR with concerning symptoms, of whom 9 (4.1%) were diagnosed with cancer. A highly suspicious CXR had a sensitivity of 94.7%, specificity 30%, and positive predictive value (PPV) of 46.7% for cancer. Conclusion: This data, from a large representative patient population, demonstrates a highly suspicious CXR is a strong predictor of malignancy. However PPV was low, resulting in a large number of non-cancer diagnoses being seen in clinic. Incidence of cancer was low in people with normal CXRs. However, CT scans were always performed, revealing occult tumours in 9 people. To streamline the diagnostic pathway in line with NOLCP, we recommend low dose CT as an initial investigation where clinical suspicion of cancer is high.