Yonemura K, et al. - As the most common pattern of metastases or recurrence in colorectal carcinoma is colorectal liver metastasis (CRLM), researchers sought for robust pathologic prognostic factors. They examined the value of poorly differentiated clusters (PDC) in the prognosis of liver metastatic lesions and ascertained how PDC in liver metastatic lesions (PDC^liver) are correlated with the primary tumor histology. Cancer clusters comprising ≥ 5 cancer cells and lacking glandular formation defined PDC. They graded PDC as G1 (< 5 clusters), G2 (5 to 9 clusters), and G3 (≥ 10 clusters) based on the highest number of clusters observed under ×20 magnification. Multivariate analysis for overall survival revealed independent prognostic factors comprising PDC^liver grade, tumor budding in the primary tumor, the number of liver metastasis and extrahepatic metastasis. In conclusion, PDC grade between the primary tumor and liver metastatic lesion were correlated, and PDC^liver grade seems to be a promising new prognostic factor after CRLM resection.