Added value of adjuvant chemotherapy in patients with node-positive pT1-2 Colon cancer - A national SNAPSHOT analysis

Abstract

Background: Patients with node-positive colon carcinoma commonly receive adjuvant chemotherapy, regardless the tumor’s T-stage. However, early-stage tumors (pT1-2 CC) are largely underrepresented in landmark studies supporting this treatment. This study evaluates the application of adjuvant chemotherapy in those patients based on daily practice. Patients and methods: Patients who underwent surgery for either pT1- or pT2-CC were identified from the nationwide SNAPSHOT database and stratified by age (<75 or ≥75 years). Competing risk regression and (cause-specific) Cox proportional hazard models identified factors associated with 5-year cumulative incidence of recurrence and overall survival (OS), respectively. Results: Lymph node metastases were found in 381 out of 2,312 (16.5%) patients, of whom 275 (72.2%) received adjuvant chemotherapy. The cumulative incidence of recurrence was 0.09 (95% CI 0.06-0.12) and 0.18 (95% CI 0.11-0.27) in patients who did or did not receive adjuvant chemotherapy, respectively (P = .007). In patients under 75, adjuvant chemotherapy was associated with significantly higher OS (91.3% vs 68.1%, P < .001). Corresponding OS probabilities in elderly patients (≥75 years) were 84.5% vs 55.1%, P = .003. After adjusting for confounding, this difference remained only significant in patients under 75: HRadj 0.5, 95% CI 0.1-0.7 and HRadj 0.5, 95% CI 0.2-1.3, respectively. The recurrence rate was not significantly different between patients receiving capecitabine/oxaliplatin (CapOx) and those on Capecitabine monotherapy (CIF 0.09, 95% CI 0.06-0.14 vs 0.05, 95% CI 0.01-0.16, P = .49). Conclusion: Adjuvant chemotherapy is associated with reduced risk of recurrence in patients with node-positive pT1-2 CC. Advantages on OS could not be demonstrated in elderly pT1-2N1-2 patients.