Survival Outcomes in High-Risk, Resected Colorectal Cancer with and without Maintenance Therapy

Abstract

Introduction: Deaths due to colorectal cancer are disproportionately higher than either breast or prostate cancers even though the majority of new cases are potentially curable at diagnoses. If only half of the losses is due to metastatic disease at diagnosis, then a share of the remaining deaths must be attributable to tumor recurrence after presumptively curative therapy of early-stage disease. If so, current management of the latter group is suboptimal for a considerable number of subjects, a perception which argues for an assessment of maintenance therapy. Moreover, most recurrences occur within 24 months after standard surgical and (neo)adjuvant therapies.
 Objective: To assess relapse-free and overall survival among patients with high-risk, resected tumors who did and did not receive maintenance therapy following completion of treatment according to accepted guidelines.
 Methods: Pertinent clinical details were collected on 85 subjects, 37 who were, and 48 who were not, treated with maintenance therapy. Descriptive statistical analyses related to survival outcomes were performed on accumulated data. Wilcoxon rank test and Fisher’s exact test were used to examine the continuous and categorical variables, respectively. Kaplan-Meier method and log-rank test were used to analyze between-group relapse-free and overall survival.
 Results: Of the entire cohort, 63 of 85 (74.1%) subjects have no evidence of disease, a median of 5 years from the end of adjuvant therapy. Kaplan-Meier analyses indicated statistically, but not necessarily clinically, non-significant differences in median 5-year relapse-free survival, 79.8% vs 69.2%, and overall survival, 87.8% vs 81.7% in the treated and untreated groups of patients, respectively. A total of 21 subjects died; three of seven (treated group) and all 14 (untreated group) due to cancer.
 Conclusion: Obscured is the hint that maintenance therapy is clinically more effective than what the p-value intimates. The results of this retrospective data collection and analyses suggest that some patients with early-stage, high-risk disease, will derive survival benefits with maintenance therapy.