Differences in the outcomes of adjuvant chemotherapy for colon cancer prescribed by physicians in different disciplines: a population-based study in Taiwan

OBJECTIVES: One feature unique to the Taiwanese healthcare system is the ability of physicians other than oncologists to prescribe systemic chemotherapy. This study investigated whether the care paths implemented by oncologists and non-oncologists differ with regard to patient outcomes. SETTING: Data from the Taiwan Cancer Registry and National Health Insurance Database were linked to identify patients with colon cancer who underwent colectomy as first treatment within 3 months of diagnosis and adjuvant chemotherapy between 2005 and 2009. PARTICIPANTS AND METHODS: Postoperative patients who underwent adjuvant chemotherapy were included in this study. The exclusion criteria included patients with stage IV disease, a positive surgical margin and early disease recurrence. Among the patients presenting with multiple primary cancers, we also excluded patients who were diagnosed with colon cancer but for whom this was not the first primary cancer. The variables included sex, age, comorbidities, disease stage, chemotherapy cycle and changes in treatment regimen as well as the specialty of treatment providers and their case volume. Cox regression models and Kaplan-Meier analysis were used to examine differences in outcomes in the matched cohorts. RESULTS: We examined 3534 patients who were prescribed adjuvant chemotherapy by physicians from different disciplines. In terms of 5-year disease-free survival, no significant difference was observed between the groups of oncologists or surgeons among patients with stage II (90.02%vs88.99%) or stage III (77.64%vs79.99%) diseases. Patients who were subjected to changes in their chemotherapy regimens presented recurrence rates higher than those who were not. CONCLUSIONS: The discipline of practitioners is seldom taken into account in most series. This is the first study to provide empirical evidence demonstrating that the outcomes of patients with colon cancer do not depend on the treatment path, as long as the selection criteria for adjuvant chemotherapy is appropriate. Further study will be required before making any further conclusions.