168O - Right-sided versus left-sided primary tumor location in patients with KRASmut metastatic colorectal cancer (mCRC) treated with 1st-line anti-VEGF p...

Date 18 December 2016
Event ESMO Asia 2016 Congress
Session Right and left colon carcinomas are different entities
Topics Anticancer Agents
Colon and Rectal Cancer
Rectal Cancer
Presenter Radka Obermannova
Citation Annals of Oncology (2016) 27 (suppl_9): ix53-ix67. 10.1093/annonc/mdw581
Authors R. Obermannova1, L. Ostřížková2, K. Hejduk3, L. Zdrazilova-Dubska4, M. Vočka5, R. Vyzula1, B. Bencsikova1, L. Petruzelka5
  • 1Clinic Of Comprehensive Cancer Care And Regional Center For Applied Molecular Oncology, Masaryk Memorial Cancer Institute, 65653 - Brno/CZ
  • 2Clinic Of Internal Medicine – Hematology And Oncology, Masaryk University Hospital Brno FN Brno Bohunice, 62500 - Brno/CZ
  • 3Masaryk University, Institute of Biostatistics and Analysis, 62500 - Brno/CZ
  • 4Department Of Laboratory Medicine, Masaryk Memorial Cancer Institute, 65653 - Brno/CZ
  • 5Department Of Clinical Oncology, General Teaching Hospital and The First Faculty of Medicine of Charles University in Prague, 12808 - Prague/CZ



CTx plus bevacizumab (bev) is a 1st-line standard for patients (pts) with mCRC. While location of the primary tumor was found to be prognostic in pts with KRASwt mCRC, especially when treated with anti-EGFR plus 1st-line CTx, the prognostic role is unknown for pts with KRASmut mCRC treated with anti-VEGF-containing CTx.


Data from 3 national comprehensive cancer centers in Czech Republic were collected prospectively from 01/2009 - 09/2015. A retrospective analysis of outcomes of 1047 pts with mCRC was performed. All pts were treated with 1st-line bev plus FOLFOX, CapOx or FOLFIRI, irrespective of the KRAS status (all-RAS since 2015). The primary objective was assessment of OS (right vs left-sided) in KRASmut mCRC. OS and PFS were calculated using the Kaplan-Meier method, Cox proportional hazards model was used to evaluate the effect of all potential prognostic factors on the survival measures.


Right-sided location of the primary tumor was in 281 of 1047 pts (26.8%), left-sided in 430 (41.1%) and rectal in 336 (32.1%). KRAS status was known in 930 pts (88.8%): 44.3% KRASwt and 44.5% KRASmut. Statistically significant differences were observed in KRAS status in right- vs left-sided mCRC vs. rectum (Fisher-exact p = 0.006). OS and PFS achieved longer time periods when compared in left- vs. right-sided mCRC. In pts with KRASmut status, OS was 19.9 mon (95% CI 15.4–24.5) in right-sided vs 25.0mon (95% CI 21.9–28.2) in left-sided mCRC; HR: 1.19 (95% CI 0.90–1.58; Wald test p = 0.231) and 23.7 mon (95% CI 19.7–27.7) in rectal cancer. Likewise, PFS was 9.6 mon (95% CI: 7.8–11.4) vs. 10.5 mon (95% CI: 9.1–11.9), HR:1.06 (95% CI 0.83–1.36, p = 0.653) in right- vs left-sided mCRC and in rectal cancer 9.9 mon, HR: 1.01 (95% CI 0.79–1.06, p = 0.934).


Although right–sided primary tumor location is a well recognized negative prognostic factor in mCRC this significance was lost when analyzing only the KRASmut subgroup of patients.

Clinical trial indentification

Legal entity responsible for the study



Masaryk Memorial Cancer Institute


All authors have declared no conflicts of interest.