Outcomes and characteristics of Danish patients undergoing a lung cancer patient pathway without getting a lung cancer diagnosis. A retrospective cohort study.

Introduction: The organ-specific Danish cancer patient pathways (CPPs) including standard time frames were introduced in 2008-2009 securing fast tracks for cancer diagnosis and treatment. Previous studies of the CPPs have focussed on patients getting the suspected cancer diagnosis, whereas little is known about patients not getting the cancer diagnosis for which they were examined. We aimed to describe the characteristics of patients who completed a lung cancer CPP (LCPP) without getting a LC diagnosis. Furthermore, to assess the proportion of patients who had invasive procedures performed during the LCPP and radiographic examinations of the chest conducted 30 days prior to the LCPP and during the LCPP. Moreover, we aimed to describe the proportion of patients being diagnosed with any other cancer-type than LC or with non-malignant pulmonary diseases (NMPDs) during the LCPP. Methods: The study was a retrospective population-based cohort study based on Danish national registers. Patients completing a LCPP between 1 January 2013 and 31 December 2016 without being diagnosed with LC and who were registered as initiating and completing the LCPP, a total of 35,809, were included in the study. Results: Invasive procedures were performed in 12,986 patients (37.4%) and almost all patients had CT-scans of thorax and lungs conducted 30 days prior to or during the LCPP. During the LCPP other cancer-types than LC were diagnosed in 1,537 patients (4.3% of the study population), including other primary thoracic malignancies in 312 patients, while 6,826 patients (19.1%) were diagnosed with NMPDs, most often infections or chronic respiratory diseases of lower airways. Conclusion: Besides diagnosing LC the LCPP may contribute significantly in diagnosing other primary and secondary cancers as well as non-malignant diseases.