Abstract 512P
Background
The ARCAD nomogram aims at predicting the 1-year survival rate in advanced colorectal (CRC) cancer patients. This prognostic tool was developed based on the clinical and biological data of patients enrolled in randomised clinical trials with a patients’ median age of 62 years (interquartile range (IQR) 55 – 69). In routine practice, the median age at CRC diagnosis reaches 68 and 72 years in male and female, respectively. Our study objective was to assess the external validity of the ARCAD nomogram in a real-life population of older patients.
Methods
This study is an ancillary analysis of the prospective ELCAPA (Elderly CAncer Patient) cohort of patients ≥70 years with as-yet untreated malignancy between 2007 and 2017. Patients were referred by cancer specialists to geriatric oncology clinics in teaching hospitals near Paris, France. We included patients diagnosed with an unresectable advanced CRC about to be treated with a first line chemotherapy regimen. We calculated the predicted 1-year survival rate based on the nomogram. Harrell's concordance c-index and Hosmer-Lemeshow analyses were used to test the nomogram discrimination and calibration. Kaplan Meier curve was displayed.
Results
A total of 123 patients with 95 deaths were included. No patient was lost to follow-up. Half of the patients were female, median age was 80 years (interquartile (IQR) 76 – 84), 64 patients had an ECOG score of 0 or 1, median overall survival was 16 months (IQR, 6,5 – 28). The median nomogram value was 160 (IQR, 142 - 177), with normal distribution across the cohort. The predicted and observed 1-yr survival rates were 50 % (95 % confidence interval (CI) 41 – 59%) and 35 % (95% CI 27 – 43%), respectively. Measures of discrimination estimated by Harrell's concordance c-index was 0.66 (95% CI 0,59 - 0,72), and Hosmer-Lemeshow calibration was p = 0.89.
Conclusions
In this external validation cohort of older patients with advanced CRC, the ARCAD nomogram showed mild calibration and moderate discrimination abilities. Older patients with CRC deserve reliable prognostic tools in order to make clinically-relevant anticancer treatment decisions.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Florence Canouï-Poitrine.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.