Higher Margin-to-Size Ratio for Intrahepatic Cholangiocarcinoma Is Associated with Recurrence-Free Survival

Kawashima J, Sahara K, Akabane M, Endo Y, et al. Oncologic Impact of Margin-to-Size Ratio for Intrahepatic Cholangiocarcinoma. J Am Coll Surg. June 2026.

The optimal surgical margin width for intrahepatic cholangiocarcinoma (ICC) remains uncertain. The authors hypothesized that the oncologic benefit of a wide margin may be modulated by tumor-related factors.

Patients who underwent curative-intent liver resection for solitary ICC were identified from a large international multi-institutional database. A novel metric, the margin-to-size ratio (MSR), was defined as the ratio of surgical margin width (mm) to tumor size (mm), integrating both parameters into a single variable. Multivariable Cox regression models were used to evaluate the association between MSR and recurrence-free survival (RFS).

Among 1,172 patients, the median tumor size was 57.0 mm, median margin width was 4.0 mm (IQR, 1.0–10.0), and median MSR was 0.07 (IQR, 0.02–0.20). On multivariable analysis, a higher MSR was independently associated with improved RFS (HR 0.59; 95% CI, 0.36–0.96; p = 0.033), whereas neither absolute margin width nor R1 resection status was associated with RFS. Using maximally selected rank statistics, an MSR threshold of 0.142 was identified. Patients with a high MSR (≥ 0.142) had superior 3-year RFS compared with patients with a low MSR (< 0.142) (55.7% [95% CI, 46.0–67.6] vs. 45.2% [95% CI, 38.0–53.8]; p = 0.016).

MSR was independently associated with RFS following ICC resection, whereas conventional margin metrics, including absolute margin width and R1 resection status, were not associated with RFS. MSR may provide a clinically interpretable framework to contextualize margin adequacy relative to tumor size and inform individualized decision-making.