RAS mutational status and CEA production at initial presentation in metastatic colorectal cancer

• Published in: Journal of clinical oncology Vol. 34; no. 4_suppl; p. 542
• Main Authors: Cho, May Thet, Goldstein, Leanne, Akiba, Chie, Lau, S. Cecilia, Telatar, Milhan, Afkhami, Michelle, Sentovich, Stephen, Melstrom, Kurt, Lim, Dean, Chao, Joseph, Chung, Vincent M., Fakih, Marwan
• Format: Journal Article
• Language: English
• Published: 01.02.2016
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/jco.2016.34.4_suppl.542

Abstract only 542 Background: Serial CEA testing is recommended in the surveillance of patients with resected stage II-IV colorectal cancer. However, the sensitivity of CEA in identifying metastatic disease has not been evaluated in the settings of RAS mutant (MT) and RAS/BRAF wild-type tumors (WT). In order to evaluate the impact of RAS mutational status on CEA production, we retrospectively evaluated a single-institute metastatic colorectal cancer (mCRC) population. Methods: We retrospectively reviewed, in a single center, all cases with mCRC with known RAS mutational status based on next generation sequencing (ONCO44 and ONCO48). These assays identify clinically relevant mutations in BRAF, KRAS, and NRAS. Additional eligibility criteria included the availability of CEA levels and imaging studies at first diagnosis of mCRC. Patient demographics, primary tumor location and sites of metastatic disease at 1 st diagnosis were captured. CEA levels were stratified as normal or elevated based on a cut point of 5ng/ml. Results: 139 mCRC patients satisfied the eligibility criteria (75 RAS-MT, 59 RAS/BRAF-WT, and 5 BRAF-MT). BRAF-MT patients were excluded from the analysis due to their small sample size. Patients with RAS/BRAF-WT tumors were more likely to present with metastatic disease to the liver, but this did not reach statistical significance (p = 0.056). There was no difference in the incidence of normal CEA at presentation in RAS-MT (30%) and RAS/BRAF-WT (28%) cohorts. CEA production was dependent on the pattern of metastatic disease. Elevated CEA was associated with the presence of liver metastases versus no metastases among RAS-MT (92% vs 47% p <.0001) and RAS/BRAF-WT patients (82% vs 50% p = 0.0101). RAS status did not impact the likelihood of CEA production within the hepatic metastases and non-hepatic metastases groups. Conclusions: RAS status does not appear to influence CEA production in patients with mCRC. CEA elevations are highly associated with liver metastases and are less prevalent in patients without hepatic involvement. These findings confirm the limited predictive value of CEA for non-hepatic recurrence, irrespective of RAS status.