The Slow Adoption of Neoadjuvant Treatment for Clinical T4b Colon Cancer: A National Cancer Database Analysis

Emerging data support the use of neoadjuvant treatment (NAT), particularly immunotherapy in microsatellite instability-high (MSI-H) tumors. We evaluate national trends in NAT utilization for clinical T4b colon cancers and its association with overall survival, with a focus on MSI-H tumors.

We conducted a retrospective cohort study using the National Cancer Database (2010-2022) evaluating patients with non-metastatic clinical T4b colonic adenocarcinoma who underwent colectomy. The primary outcome measures were trends in NAT utilization and overall survival.

Among 8862 patients with clinical T4b colon cancer, NAT utilization increased over time, peaking at 28% in the most recent quartile. NAT recipients were more likely younger, healthier, and to be treated at academic centers. NAT was associated with higher R0 resection rates (83% vs 77%, p < 0.001) and significantly longer mean overall survival (105 vs 80 months, p < 0.001). Among MSI-H patients (11% of the cohort), 15% received NAT. Immunotherapy use increased steadily, surpassing chemotherapy in 2022. Patients receiving neoadjuvant immunotherapy +/- chemotherapy demonstrated superior survival to chemotherapy alone (106 vs 85 months, p < 0.001).

Neoadjuvant therapy use has increased nationally, with a notable rise in immunotherapy for MSI-H tumors. Neoadjuvant treatment, particularly immunotherapy, is associated with significant overall survival benefit.