551P - Adjuvant chemotherapy (AC) use and outcomes in stage II colon cancer (CC) with vs. Without poor prognostic features

Date 01 October 2012
Event ESMO Congress 2012
Session Poster presentation III
Topics Cytotoxic agents
Colon and Rectal Cancer
Therapy
Biological therapy
Presenter Aalok Kumar
Authors A. Kumar1, H. Kennecke1, H. Lim2, D. Renouf2, R. Woods1, C. Speers1, W. Cheung1
  • 1Medical Oncology, British Columbia Cancer Agency, V5Z4E6 - Vancouver/CA
  • 2Medical Oncology, British Columbia Cancer Agency, Vancouver/CA

Abstract

Background

AC is frequently considered in patients (pts) with “high risk” stage II CC, defined by the presence of >/ = 1 poor prognostic features: obstruction or perforation, T4 stage, <12 lymph nodes removed, positive margins, and lymphovascular or perineural invasion. Survival benefits associated with AC use in high risk pts remain largely unproven. Our aims were to examine patterns of AC use in stage II CC and the impact on survival in high vs low risk pts.

Methods

All pts with stage II CC in British Columbia from 1999 to 2008 and evaluated at 1/5 regional centers were reviewed. Kaplan-Meier and Cox regression methods were used to correlate high vs low risk status and receipt of AC with relapse-free (RFS), disease specific (DSS) and overall survival (OS).

Results

We identified 1,697 pts: 1,236 (73%) high risk and 461 (27%) low risk among whom 363 (29%) and 61 (13%) received AC, respectively. Individuals with high risk disease who received AC were younger (median 62 vs 72 yrs p < 0.001) and had better performance status (ECOG 0/1 47% vs 34%, p = 0.02). For high risk pts, AC was associated with improved 5-year OS (Table 1). Adjusting for confounders, an OS advantage from AC persisted for high risk pts (HR 0.67, 95CI 0.52-0.86, p = 0.002), with no significant RFS or DSS benefits. Subgroup analyses revealed individuals with T4 lesions had significantly improved RFS (HR 0.63, 95CI 0.42-0.95, p = 0.03), DSS (HR 0.59, 95CI 0.37-0.93, p = 0.02), and OS (HR 0.50, 95CI 0.33-0.77, p = 0.001). For low risk pts, AC was associated with decreased RFS (HR 2.27, 95CI 1.03-4.97, p = 0.04) and DSS (HR 2.97, 95CI 1.10-8.02, p = 0.03).

Conclusions

In this population-based cohort study, AC was associated with an OS advantage in high risk pts, likely due to pt selection. RFS and DSS benefits were mainly seen in T4 lesions, suggesting a limited role for AC in pts deemed high risk. A possible trend towards harm was seen in the low risk group receiving AC. Risk stratification based on molecular testing should be further explored. Table 1:

3yr RFS % p value 5yr DSS % p value 5yr OS % p value
High risk
AC 78 0.98 80 0.83 75 <0.01
No AC 80 79 68
Low risk
AC 87 0.18 93 0.78 87 0.26
No AC 93 93 85
Disclosure

All authors have declared no conflicts of interest.