Impact of the IDEA Collaboration Study on Real-World Practice Patterns of Adjuvant Chemotherapy in Patients With...

The International Duration Evaluation of Adjuvant Chemotherapy (IDEA) collaboration showed no significant clinical difference in outcomes in patients with stage III colon cancer (CC) treated with 3 versus 6 months of oxaliplatin-based adjuvant chemotherapy (O-ACT). We aimed to assess change in real-world practice patterns before and after publication of the IDEA study.

This retrospective cohort study included patients age ≥18 years with stage III CC diagnosed between January 1, 2012, and December 31, 2020. Eligible patients received >1 dose of ACT between March 20, 2012, and May 10, 2021 inclusive. They were categorized into pre-IDEA (diagnosed before March 31, 2018) and post-IDEA (diagnosed on or after April 1, 2018) groups. The primary outcome was the median duration and type of ACT and factors associated with a shorter duration. Secondary outcomes were 2-year overall survival (OS) and cancer-specific survival (CSS).

In total, 740 patients were included (median age, 64 years, range, 27-90; 52.7% male). 48.8% had pT4 and/or pN2 disease. 77% received O-ACT. In the post-IDEA era, capecitabine plus oxaliplatin (CAPOX) ACT use increased (22.8%-50.7%, P < .001), and median duration of treatment was significantly shorter (2.7 v 4.8 months, P < .001). Factors associated with shorter O-ACT duration included diagnosis in the post-IDEA era (odds ratio, 2.08, P = .002), absence of pT4 and/or pN2 disease (hazard ratio [HR], 1.71, P = .01), and receipt of CAPOX (HR, 2.58, P < .001). Two-year OS and CSS were comparable between pre- and post-IDEA eras (OS 95% v 94%; CSS 96% v 96%).

Our study shows that the results of the IDEA trial have been largely adopted in clinical practice with shorter duration of ACT in low-risk stage III CC.