Objective:

To evaluate the impact of time-to-surgery (TTS) on postoperative morbidity and oncologic outcomes following surgery for colorectal liver metastases (CRLM) after neoadjuvant systemic therapy (NAT).

Approach:

• Study Design: A retrospective cohort study of 159 patients who underwent oncologic resection of CRLM following NAT at Heidelberg University Hospital.
• Participants: Included adult patients with histologically confirmed synchronous or metachronous CRLM who received NAT prior to surgery.
• Variables: Primary exposure was TTS, analyzed continuously and categorized at various intervals (≥ 35, 42, 49, 56 days).
• Outcomes: Primary outcome was postoperative morbidity (CCI > 30), secondary outcomes included liver-specific recurrence-free survival (RFS) and overall survival (OS).
• Statistical Methods: Used logistic regression for morbidity and Cox models for survival, with adjustments for confounding variables.

Key Findings:

• Postponing surgery beyond six weeks after NAT was associated with lower postoperative complications.
• No significant compromise on oncological outcomes was observed with delayed surgery.

Interpretation:

Delaying surgery after NAT may reduce postoperative complications without negatively impacting long-term oncological outcomes in patients with CRLM.

Limitations:

• Retrospective design may introduce selection bias.
• Findings are based on a single institution, limiting generalizability.

Conclusion:

Postponing surgery beyond six weeks after NAT may reduce postoperative complications in patients with CRLM.