Protocol for a mixed-method study to assess chronic cough in patients with renal cell carcinoma: the prevalence, impact on quality of life, trigger and potential clinical application of chronic cough as an early screening tool in patients with kidney cancer

INTRODUCTION: Cough as a symptom of renal cell carcinoma (RCC) was first described by Creevy in 1935, and despite one (unpublished) study suggesting it may affect 31% of these patients, as well as cough being discussed in forums for patients with kidney cancer, few clinicians are aware of this association. The cough has been described as unusual in nature, resolving rapidly after treatment with nephrectomy/embolisation but returning if the tumour recurs. METHODS AND ANALYSIS: A prospective study using a questionnaire will identify the prevalence of cough in patients with suspected or confirmed RCC attending the Specialist Centre for Kidney Cancer (London, UK). A longitudinal study in a representative sample of these patients, using EQ-5D-5L and Leicester Cough Questionnaires, together with the use of semi-structured interviews with patients, will identify the impact of cough in addition to having a diagnosis of suspected or confirmed RCC on quality of life. To investigate cough mechanisms, a pilot study using cough hypersensitivity testing will be performed on patients with RCC, with and without a cough. Clinical samples (urine, blood, phlegm and breath condensate) from patients with RCC, with and without a cough, will be collected and analysed for the presence of substances known to trigger or enhance cough and compared with the results obtained from healthy volunteers. ETHICS AND DISSEMINATION: Ethical approval has been granted (UK HR REC 22/PR/0791 dated 25/08/2022). Study outputs will be presented and published nationally and internationally at relevant conferences. This study will establish the prevalence of cough in patients with suspected or confirmed kidney cancer and support the education of clinicians to consider this diagnosis in patients with chronic cough (eg, recommending protocols to include both kidneys when investigating respiratory symptoms with chest CT scans). If substances known to trigger or enhance cough are identified and elevated in clinical samples, this research could offer potential targets for treatment for this distressing symptom. TRIAL REGISTRATION NUMBER: NIHR CRN portfolio CPMS ID:53 372.