1405P - Diagnostic analysis of patients referred from general practitioner with serious non-organ-specific symptoms and signs of cancer: A retrospective cohort study

Abstract

Background: Recently, a diagnostic fast track for patients with serious non-organ-specific symptoms and signs of cancer was established in Denmark. For patients without cancer diagnosed within the first month, the prognosis is currently unclear. Methods: A retrospective cohort study of 926 patients referred to Diagnostic Outpatient Clinic (DOC) at Herlev Hospital from April 2012 to December 2013. Baseline clinical parameters were collected from patient records. Time to cancer, death, cancer specific mortality (CSM), and death due to other causes were recorded until May, 2016. 724 patients were identified without cancer one month after examination and divided into 2 sub-cohorts based on the initial assessment: true negatives (TNs; patients diagnosed without cancer at DOC and after 1 month) and false positives (FPs; patients referred from DOC with suspicion of cancer, but without cancer the 1. month). Cumulative incidence of cancer, death, CSM, and death from other causes were estimated by the Aalen-Johansen estimator using 31 days after initial assessment as baseline. Hazard radios (HR) and 95% confidence intervals (CIs) for the initial evaluation were estimated in Cox models with cancer and mortality, respectively, as outcomes. Results: Clinical characteristics of the 724 patients: median age 65 years (range 17-92); 44% were men; 70% were referred from their general practitioner; 43% were former/current smokers; 18% were former/current alcohol abusers. The median age (p < 0.01) and comorbidity score (p < 0.01) were highest among the FPs. TNs vs. FPs had a lower risk of subsequent cancer (HR: 0.08; 95% CI: 0.05-0.13; p < 0.01), mortality (HR: 0.26; 95% CI: 0.16-0.41; p < 0.01) and CSM (HR: 0.07; 95% CI: 0.03-0.16; p < 0.01). Mortality from other causes was similar in the two groups (HR: 0.58; 95% CI: 0.29-1.19; p = 0.14). The negative predictive value (NPV) was 0.94 and the positive predictive value was 0.46. However, around 40% of the FPs was diagnosed with cancer within the first year. Conclusions: Ruling out cancer by investigation at DOC was associated with low risk of subsequent cancer and the NPV was high. The FPs had higher risk of cancer, mortality, and CSM compared to the TNs. Legal entity responsible for the study: Claus Larsen Feltoft Funding: Department of Internal Medicine, Herlev and Gentofte Hospital (no specific grant number); Danish Cancer Society (grant number: R152-A9695-16-S7). Disclosure: All authors have declared no conflicts of interest.