Multicenter validation study of pathologic response and tumor thickness at the tumor-normal liver interface as independent predictors of disease-free survival after preoperative chemotherapy and surgery for colorectal liver metastases

Abstract

BACKGROUND To validate pathologic markers of response to preoperative chemotherapy as predictors of disease-free survival (DFS) after resection of colorectal liver metastases (CLM). METHODS One hundred seventy-one patients who underwent resection of CLM after preoperative chemotherapy at 4 centers were studied. Pathologic response - defined as the proportion of tumor cells remaining (complete, 0%; major, <50%; minor, ≥50%) and tumor thickness at the tumor-normal liver interface (TNI) (<0.5 mm, 0.5 to <5 mm, ≥5 mm) - was assessed by a central pathology reviewer and local pathologists. RESULTS Pathologic response was complete in 8% of patients, major in 49% of patients, and minor in 43% of patients. Tumor thickness at the TNI was <0.5 mm in 21% of patients, 0.5 to <5 mm in 56% of patients, and ≥5 mm in 23% of patients. On multivariate analyses, using either pathologic response or tumor thickness at TNI, pathologic response (P =.002,.009), tumor thickness at TNI (P = 0.015,