Perihepatic lymph node micrometastases impact outcome after partial hepatectomy for colorectal metastases

Hepatectomy for resectable colorectal liver metastases provides a survival advantage but is usually reserved for patients without extrahepatic disease. Metastases to perihepatic lymph nodes (LN) occur with controversial significance. This study uses standard pathologic analysis and immunohistochemistry (IHC) to determine the impact of occult metastatic disease to perihepatic LN in patients with colorectal cancer undergoing hepatectomy. Fifty-nine patients with liver metastases from colon or rectal primary cancer were studied prospectively. Perihepatic LN were sampled from the portocaval, pancreaticoduodenal, and common hepatic artery regions. All LN were analyzed using hematoxylin and eosin (H&E), and those negative by H&E were analyzed using IHC for cytokeratin. Recurrence and survival were compared amongst LN groups. Median follow-up was 42 months for survivors. There were eight patients with metastatic disease to at least one perihepatic LN identified by H&E and fourteen patients with metastases identified by IHC only. Forty-one patients (70%) recurred after resection, and patients with LN metastases, regardless of detection method, had a shorter recurrence-free survival compared to node negative patients. However, patterns of recurrence differed by LN group. Compared to H&E-positive patients, IHC-positive patients had a better overall survival and were more likely to recur at a single site amenable to salvage resection. In patients with hepatic colorectal metastases, IHC analysis of perihepatic LN adds prognostic value regarding the timing and burden of recurrence after resection. Routine IHC assessment of perihepatic LN is reasonable since the information garnered would potentially influence postresection chemotherapy recommendations.