Factors associated with the lack of adjuvant chemotherapy following curative surgery for stage II and III colon cancer: A Korean national cohort study

Background: To evaluate factors associated with the lack of adjuvant chemotherapy after curative surgery in patients with stage II and III colon cancer based on national population-based data. Patients and Methods: A total of 8,412 patients diagnosed with stage II or III disease who underwent curative resection were included. Results: Adjuvant chemotherapy was not administered in 3,057 cases (36.34%). Factors associated with the lack of chemotherapy were older age [hazard ratio (HR)=1.50 in patients 65-74 years and 5.23 in patients ≥75 years of age], female sex (HR=1.15), tumor-node-metastasis (TNM) stage II (HR=4.28), emergency surgery (HR=1.45), American Society of Anesthesiologists (ASA) score of 3 or higher (HR=1.62), fewer than 12 lymph nodes examined (HR=1.19), a greater quantity of transfusion (HR=1.08), and hospital type (tertiary referral center) (HR=1.62). Conclusion: Patientrelated (older age, female sex, and ASA score of 3 or higher) and treatment-related factors (TNM stage II, emergency surgery, fewer than 12 lymph nodes examined, a greater quantity of transfusion, and hospital type) influenced the lack of adjuvant chemotherapy. Given that the use of adjuvant chemotherapy improves overall survival, physicians should make an effort to increase the proportion of patients receiving chemotherapy after surgery.