Importance of complete pathologic response to prehepatectomy chemotherapy in treating colorectal cancer metastases

Abstract

Objective: We studied the influence of complete pathologic response of colorectal cancer liver metastases to prehepatectomy chemotherapy on longterm survival after hepatectomy.

Summary background data: Although complete response seen on imaging may be a useful criterion for evaluating efficacy of chemotherapy, complete clinical response by imaging has shown limited predictive value for complete pathologic response in treating colorectal liver metastases.

Methods: We retrospectively analyzed data from 63 patients who received preoperative chemotherapy and underwent hepatectomy.

Results: Of 472 liver metastases evaluated, 86 were no more visible from images after chemotherapy. We excluded 14 of these metastasis treated with local ablation. Of the remaining 72 metastasis, 22 (30.6%) were microscopically persistent metastases or recurrences in situ. Liver metastases with complete pathologic response had smaller diameters at diagnosis than others (P < 0.001), and microscopic cancer deposits surrounding macroscopic tumors were less frequent in patients with complete pathologic response than others (P < 0.05). Outcomes were favorable in patients whose liver metastases all showed a complete pathologic response. Even patients with complete pathologic response in only some metastases showed higher overall and disease-free survival rates than pathologic nonresponders (P = 0.001 and P = 0.002, respectively). Presence or absence of metastases showing complete pathologic response was an independent prognostic factor (relative risk, 4.464; P = 0.0099).

Conclusions: Little correlation was observed between imaging response of colorectal cancer liver metastases to chemotherapy and pathologic response. Liver surgery should be undertaken even after a complete response by imaging. Outcome after hepatectomy was favorable in patients showing complete pathologic response of least one metastasis.