Prognostic Factors and the Role of Adjuvant Chemotherapy in Post-curative Surgery for Dukes B and C Colon Cancers and Survival Outcomes: a Malaysian Experience

Background: Adjuvant chemotherapy improves survival in Dukes C colon cancers post-curative resection.However, the evidence for a role with Dukes B lesions remains unproven despite frequent use for diseasecharacterized by poor prognostic features. In view of limited Asia-specific data, this study aimed to determinesurvival outcomes and identify prognostic factors in a tertiary teaching hospital in Malaysia. Materials and
Methods: A total of 116 subjects who underwent curative surgery with and without adjuvant chemotherapy forDuke B and C primary colon adenocarcinomas diagnosed from 2004-2009 were recruited and data were collectedretrospectively. Five-year overall survival (OS) and disease free survival (DFS) were analysed using Kaplan-Meiersurvival analysis and log-rank (Mantel-Cox) test. Prognostic factors were determined using Cox proportionalhazards regression with both univariate and multivariate analyses.
Results: The survival analysis demonstrateda 5-year OS of 74.0% for all patients, with 74.9% for Dukes C subjects receiving chemotherapy compared to28.6% in those not receiving chemotherapy (p=0.001). For Dukes B disease, the 5-year survival rate was 82.6%compared to 75.0% for subjects receiving and not receiving chemotherapy, respectively (p=0.17). Independentprognostic factors identified included a CEA level more than 3.5 ng/ml (hazard ratio (HR)=4.78; p=0.008),serosal involvement (HR=3.75; p=0.028) and completion of chemotherapy (HR= 0.20; p=0.007).
Conclusions:In a regional context, this study supports current evidence from the West that adjuvant chemotherapy improvessurvival in Dukes C colon cancers post curative surgery. However, although a clear benefit has yet to be provenfor Dukes B disease, our results suggest survival improvement in selected cases.