Real-World Evidence on Adjuvant Chemotherapy After Resection of Left-Sided Obstructive Colon Cancer

Background: Bowel obstruction is considered a poor prognostic factor in colon cancer. Therefore, these patients are generally treated with adjuvant chemotherapy following resection of the primary tumour. However, the benefit of adjuvant chemotherapy in stage II obstructive colon cancer, and the impact of bridge-to-surgery strategies are insufficiently known. 

Methods: This was a nationwide cohort study of patients who underwent resection of left-sided obstructive colon cancer (LSOCC) with curative intent in 75 hospitals between 2009 and 2016. Potential predictors for receiving adjuvant chemotherapy were included in a multivariable model. The impact of adjuvant chemotherapy on disease-free survival (DFS) and overall survival (OS), corrected for age, ASA-score, and 30-day postoperative complications, was determined using Cox regression analyses, with pTN stratification. 

Results: Of 2151 included patients, 39.7% received adjuvant chemotherapy. Independent predictors of receiving adjuvant chemotherapy were age, ASA score, pT and pN1-2 categories, and Clavien-Dindo grade III-IV postoperative complications, but not a bridge-to-surgery strategy. Adjuvant chemotherapy was independently associated with better DFS (HR: 0.61; 95% CI, 0.51-0.72) and OS (HR: 0.49; 95% CI, 0.40-0.61) in the overall population. In pT3N0 LSOCC, adjuvant chemotherapy was not associated with DFS or OS. In patients with pT4N0 LSOCC however, adjuvant chemotherapy was associated with improved DFS (HR: 0.53, 95% CI, 0.29-0.95) and OS (HR: 0.42, 95% CI, 0.20-0.86). No differences in DFS or OS were observed between patients who received single-agent versus doublet chemotherapy were found. 

Conclusion: A bridge-to-surgery strategy did not influence adjuvant chemotherapy receipt in patients with LSOCC. Obstruction is considered a risk factor in stage II, but no survival benefit of adjuvant chemotherapy is seen for the pT3N0 subgroup.