Colorectal metastases with intrabiliary growth: incidence, treatment, and outcomes

Intrabiliary growth (IG) is an unusual modality for colorectal metastases to spread. Relatively little is known about this condition because large series are lacking. The aim of the study was to compare the surgical and oncological outcomes of patients with or without IG. From 01/2010 to 12/2020, 999 patients underwent hepatectomy for colorectal metastases. Clinicopathological variables were retrospectively analyzed from a prospective-collected database of patients with or without IG. A propensity score matched (PSM) analysis to compare OS and DFS was performed. At first hepatectomy, 29 patients (2.9%) had IG: 7 isolated IG and 22 mixed-type (mass-forming lesion with IG). 4 patients presented IG at repeat hepatectomy for recurrence, of whom 3 had no biliary invasion at initial surgery. IG resulted to be more common in older patients (median age 70 in IG vs 60 years of no-IG, p = 0.004). Mean time from colorectal tumor was longer in IG (20.4 months) than no-IG (12.9 months), p = 0.038. Major hepatectomies (55.2% IG vs 29.7% no-IG, p = 0.003) and anatomic resections (89.7% vs 58.2%, p = 0.001) were more frequently required to treat IG. In 5 (17%) of IG, a resection of main bile duct was performed. Overall postoperative mortality and complications were similar in the two groups, while bile leak was 17.2% IG vs 5.6% no-IG (p = 0.024). Median margin width was comparable in IG (1.4 mm) and no-IG (2 mm). Five-year overall survival (IG 45.9% vs no-IG 44.5%) and Disease-Free Survival (IG 35.9% vs no-IG 36.6%) were similar in the two groups. According to PSM, 145 patients with no-IG were compared to 29 of IG group. After PSM, OS and DFS did not show any statistically significant difference. IG has similar oncological outcomes of resected colorectal metastases without IG, although it affects surgical management.