Postchemotherapy characteristics of hepatic colorectal metastases: remnants of uncertain malignant potential.

Accepted management for colorectal cancer (CRC) involves resection of the primary neoplasm and chemotherapy; the debate continues over the most beneficial order of these components. Preoperative chemotherapy aimed at liver metastases may result in complete pathologic response and replacement of the malignancy with scar. The McGill University liver diseases database was retrospectively reviewed. Forty-one patients receiving treatment between December 2003 and August 2004 were identified, their medical records examined, and liver histology reviewed. The histology of the remnants was linked to the appearance of the lesions on preresection imaging and to the primary colorectal neoplasms. Twenty-seven of the 41 patients (66%) received preoperative chemotherapy (oxaliplatin or irinotecan). Features of the primary neoplasm that predicted resolution of the metastases were absence of tumor budding (P = 0.04), absence of a diffusely infiltrative tumor margin (P = 0.02), and loss of expression of the DNA repair gene O6-methylguanine-DNA methyltransferase (P = 0.08). Oxaliplatin and irinotecan demonstrate beneficial effects in treating hepatic colorectal metastases and should be considered in such patients before resection. We propose the acronym RUMP to denote the remnants of uncertain malignant potential remaining. Further investigation is required to determine any correlation between the drug received and the resulting lesion.