Selecting Lung Cancer Patients from UK Primary Care Data: A Longitudinal Study of Feature Trends

A high proportion of lung cancer cases are detected at a late cancer stage when they present with symptoms to general practitioners (GP). Early diagnosis is a challenge because many symptoms are also common in other diseases. Therefore, this study aims to assess UK primary care data of patients one, two and three years prior to lung cancer diagnosis to capture trends in clinical features of patients with the goal of early diagnosis and thus potentially curative treatment. This longitudinal study utilises data from the Clinical Practice Research Datalink (CPRD) with linked data from the National Cancer Registration and Analysis Service (NCRAS). A comprehensive list of Read codes is created to select features of interest to establish if a patient has experienced a certain medical condition or not. The comparison of the relative frequencies of the identified predictors associated with cases and controls reveals the importance of the following groups of features: ‘Cough Wheeze’ and ‘Bronchitis unspecified’, ‘Dyspnoea’ and ‘Upper Respiratory Infection’, which are frequent events for lung cancer cases, where a high proportion of cases were also identified using ‘Haemoptysis’ and ‘Peripheral vascular disease’.