Analysis of the benefit of the adjuvant chemotherapy in stage II colon cancer according to the presence of classic poor risk factors: Our experience in Ramon y Cajal Hospital
Authors: C. Saavedra Serrano, M. Villamayor Delgado, E. Corral de la Fuente, A. Barquín García, J. Serrano Domingo, R. Martín Huertas, O. Martínez Saez, F. Longo Muñoz, P. Reguera Puertas, V. Pachón Olmos, M. Rodriguez Garrote, M. Vaz, R. Fuentes, A. Carrato, R Ferreiro Monteagudo
Journal: Annals of Oncology (2018)

Introduction: Despite surgery is a curative treatment for colon cancer (CC), recurrence is common. The role of adjuvant chemotherapy (AC) in stage II CC is controversial. Classically, certain factors have been associated with poor prognostic outcomes and they are widely considered in the decision making algorithm for stage II CC. Methods: We conducted an unicentric retrospective study. Patients with resected stage II CC between 2009 and 2014 were identified. Univariate analysis were performed for classic high risk factors (CRF), and those which obtained a p < 0.05 were incorporated in a multivariate model. In addition, we analyzed the relapse free survival (RFS) and overall survival (OS) rates according to the presence of at least one risk factor. Finally, we studied the benefit of AC in patients depending on the presence or absence of risk factors. Cox regression was employed for the analysis. Results: 282 patients were identified. 60% were men. Median age at diagnosis was 74 years. The most were right sided (55%) and stage IIA (86%). 62% had at least one CRF. 30% of all patients received AC, most of them having at least one risk factor (82%). Median follow up was 60,2 months. Median 5-year RFS was 67,3% and the 5-year OS rate was 76,8%. In the univariate analysis for OS: T stage, the presence of perforation or obstruction and positive margins were significant prognostic factors (HR 2.1, 2.3, 2.8 and 2.9 respectively). In the multivariate model: obstruction, perforation and positive margins were independent risk factors for OS (HR 3.1, 1.9 and 3.2 respectively). The same analysis for RFS was performed: T stage, lymphovascular infiltration, perforation or obstruction, positive margins and presurgical CEA elevation were significant risk factors in the univariate analysis (HR 2.1, 2, 2.1, 2.6, 2.3 and 2.4, respectively). Presurgical CEA elevation and lymphovascular infiltration were the only prognostic factors in the multivariate model (HR 3.6 and 4.6, respectively). Having at least one CRF represented a detrimental factor for OS (HR 1.9, p = 0,015) and RFS (HR 2.2, p = 0.022). According to risk factors identified in our analysis, similar results were found for OS (HR 2.99, p < 0.001) and RFS (HR 1.8, p = 0.008). In addition, patients with at least one CRF receiving AC had benefit in OS (HR 0.27, p < 0.001) and RFS (HR 0.49, p 0.012), while there was not benefit in patients without any CRF neither for OS or RFS. However, stratifying patients only according to risk factors identified in our analysis, does not discriminate accurately which patients benefit from AC. Conclusion: Adequate selection of patients with stage II colon cancer who can benefit from AC is essential for avoid overtreatment and for improve prognosis of those patients with higher risk. In this way, CRF seems to stratify properly patients who benefit from an AC and those who need closer surveillance. However, more precise information is needed and including molecular biomarkers could help to accurate decision making in the near future.