Anastomotic leak and oncologic outcomes after colorectal cancer resection: A real-world analysis.

71 Background: Anastomotic leak (AL) is a serious complication after colorectal cancer resection and may worsen outcomes via inflammation, impaired recovery, and delayed adjuvant therapy. Multi-institutional evidence is limited. We assessed the association between AL and long-term outcomes. Methods: Adults with colorectal cancer undergoing colectomy in TriNetX were included; surgery was the index date. AL was reoperation, stoma creation/revision, gastrointestinal bypass, or image-guided drainage within 30 days. Controls had no AL-related codes within 90 days. Outcomes were overall mortality and distant metastatic disease—M1 or secondary malignant neoplasms of non-regional lymph nodes or distant organs (ICD C77–C79)—analyzed as time-to-event endpoints. Covariates included demographics, comorbidities, and labs. We used propensity score weighting and time-dependent Cox regression. Sensitivity analyses extended AL to 60 and 90 days. Subgroups were stratified by tumor location (colon vs rectum). Results: We identified 51 596 patients; 10 939 per group remained after matching. AL was associated with higher hazards of overall mortality (HR 1.69, 95% CI 1.59–1.80) and distant metastatic disease (HR 1.54, 95% CI 1.46–1.64). Results were consistent across sensitivity analyses and alternative AL definitions. In colon cancer, AL was associated with higher mortality (HR 1.68, 95% CI 1.56–1.82) and distant metastatic disease (HR 1.57, 95% CI 1.45–1.69); in rectal cancer, AL was also linked to increased mortality (HR 1.37, 95% CI 1.17–1.59) and metastatic disease (HR 1.29, 95% CI 1.14–1.45). Conclusions: Postoperative AL is independently linked to higher mortality and distant metastatic disease after colorectal cancer resection, underscoring its oncologic impact and the need for prevention and timely adjuvant therapy. Association of anastomotic leak with oncologic outcomes. Outcome HRs (CI) p-value Overall Mortality 1.689 (1.587, 1.799)