Evaluating the oncological safety of neoadjuvant chemotherapy in locally advanced colon carcinoma: a systematic review and meta-analysis of randomised clinical trials and propensity-matched studies.

Purpose: Use of neoadjuvant chemotherapy (NAC) for locally advanced colon cancer (LACC) remains controversial. An integrated analysis of data from high-quality studies may inform the long-term safety of NAC for this cohort. Our aim was to perform a systematic review and meta-analysis of randomised clinical trials (RCTs) and propensity-matched studies to assess the oncological safety of NAC in patients with LACC.

Methods: A systematic review was performed as per preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Survival was expressed as hazard ratios using time-to-effect generic inverse variance methodology, while surgical outcomes were expressed as odds ratios (ORs) using the Mantel-Haenszel method. Data analysis was performed using Review Manager version 5.4.

Results: Eight studies (4 RCTs and 4 retrospective studies) including 31,047 patients with LACC were included. Mean age was 61.0 years (range: 19-93 years) and mean follow-up was 47.6 months (range: 2-133 months). Of those receiving NAC, 4.6% achieved a pathological complete response and 90.6% achieved R0 resection (versus 85.9%, P < 0.001). At 3 years, patients receiving NAC had improved disease-free survival (DFS) (OR: 1.28, 95% confidence interval (CI): 1.02-1.60, P = 0.030) and overall survival (OS) (OR: 1.76, 95% CI: 1.10-2.81, P = 0.020). When using time-to-effect modelling, a non-significant difference was observed for DFS (HR: 0.79, 95% CI: 0.57-1.09, P = 0.150) while a significant difference in favour of NAC was observed for OS (HR: 0.75, 95% CI: 0.58-0.98, P = 0.030).

Conclusion: This study highlights the oncological safety of NAC for patients being treated with curative intent for LACC using RCT and propensity-matched studies only. These results refute current management guidelines which do not advocate for NAC to improve surgical and oncological outcomes in patients with LACC.

Trial Registration: International Prospective Register of Systematic Review (PROSPERO) registration: CRD4202341723.