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 Anti-Cancer Agents & Biologic Therapy
Biomarkers
Colon 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

Abstract

Background

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.

Methods

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.

Results

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).

Conclusions

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

N/A

Funding

Masaryk Memorial Cancer Institute

Disclosure

All authors have declared no conflicts of interest.