Efficacy of adjuvant chemotherapy for elderly patients with colon cancer
Authors: M. Villamayor Delgado, C. Saavedra Serrano, E. Corral de la Fuente, A. Barquín García, O. Martínez Saez, R. Martín Huertas, J. Serrano Domingo, J. Molina Cerrillo, F. Longo Muñoz, V. Pachón Olmos, M. Rodriguez Garrote, P. Reguera Puertas, M. Vaz, A. Carrato, R. Ferreiro Monteagudo
Journal: Annals of Oncology (2018)

Introduction: The benefit of adjuvant chemotherapy (fluoracil or capecitabine with or without oxaliplatin) has been well established in the adjuvant setting for node-positive colon cancer (stage III). The extent to which older adults benefit from adjuvant chemotherapy was not well established in the different trials (MOSAIC, NSABP C-07, N016968) given that there was no participation of patients older than 75 years old. However, in the latest published systematic reviews there are contradictory results on the efficacy of adjuvant chemotherapy in this population. Methods: We retrospectively included patients with stages II and III colon cancer that underwent surgical treatment between 2009 and 2014 at the University Hospital Ramón y Cajal (Madrid). We calculated DFS and OS at 48 months and we performed a univariate and multivariate Cox model analysis to estimate the benefit of chemotherapy for different age groups (cut-off point 70 years) and stage at diagnosis. The model was further adjusted by including the following confounding factors: ECOG-PS, grade, number of resected nodes, CEA before surgery, colon side location, stage and presence of obstruction/perforation. A covariate was considered a confounding factor if the difference between the adjusted and unadjusted chemotherapy coefficient varied> 10%. Stata 13.1 was used to analyse the data. Results: 551 patients were identified (166 patients <70 years old and 385 patients ≥ 70 years old). 281 were stage II (51%) of which 220 were older than 70 years old and 270 were stage III (49%) of which 165 were older than 70 years old. In addition, 220 had ECOG-PS: 0 but 331 had ECOG-PS greater than 0 (43%, 1). 248 received chemotherapy and 303 did not. The median follow-up in the entire cohort was 49 months. The median DFS and OS were not reached at the moment of the analysis. DFS and OS at 48 months were both 78.5%. Globally, chemotherapy did not improve DFS (HR 0, 72, p 0, 43) but OS was significantly better (HR 0, 36, p 0,005). By stage, chemotherapy did not improve DFS in stage II (HR: 0, 67, p: 0.2) nor OS (HR 0.4, p: 0.085). In stage III, chemotherapy showed a trend to improve DFS (HR de 0, 23, p 0, 58) and did clearly improve OS (HR 0,071, p 0,002). Nevertheless, the univariate analysis of the global population shows benefit in both DFS (HR 0,657 p 0,031) and OS (HR 0,257 (IC: 0,149 – 0,445) p 0,002) probably affected by confounding factors (ECOG-PS, presence of obstruction/perforation and number resected nodes). Conclusion: The multivariable analysis showed benefit of chemotherapy in patients older than 70 years old with stage III colon cancer, with a 77% reduction in the risk of recurrence and a 29% in the risk of death. However, in stage II patients these benefits were not found either in PFS or OS. More prospective studies in this population group are needed to confirm these findings.