A study published by Yonemura et al in The American Journal of Surgical Pathology has shown a correlation between the poorly differentiated cluster grade in primary colorectal cancer tumors and metastatic lesions in the liver. The researchers wrote, “[Grade of] poorly differentiated clusters in liver metastatic lesions could be a promising new prognostic factor after colorectal cancer liver metastasis resection.”
Methods
In addition to verifying the prognostic value of poorly differentiated clusters in metastatic liver lesions, study researchers also sought to clarify the correlation between such clusters and primary tumor histology.
A total of 204 patients who underwent resection for colorectal cancer liver metastases were pathologically reviewed; poorly differentiated clusters were defined as cancer clusters comprising ≥ 5 cancer cells and lacking glandular formation; poorly differentiated cluster status was quantifiably graded as grade 1 (< 5 clusters), grade 2 (5–9 clusters), and grade 3 (≥ 10 clusters) based on the highest number of clusters observed under ×20 magnification.
Results
Poorly differentiated cluster status in liver lesions was classified as grade 1 in 68 patients, grade 2 in 69 patients, and grade 3 in 67 patients, and was significantly associated with poorly differentiated cluster grade in the primary tumor (P < .001). Tumor budding in the primary tumor, poorly differentiated clusters in the primary tumor, number of liver metastases, extrahepatic metastases, and poorly differentiated clusters in liver lesions all significantly impacted overall survival after resection of colorectal cancer liver metastases.
Five-year overall survival rates were influenced according to the grade of poorly differentiated clusters in liver lesions—68.9% for patients classified as grade 1, 48.3% for grade 2, and 39.5% for grade 3 (P < .001). Multivariate analysis for overall survival showed that poorly differentiated clusters in liver lesions grade, tumor budding in the primary tumor, number of liver metastases, and extrahepatic metastases were independent prognostic factors.
The authors concluded, “There is a correlation in the poorly differentiated cluster grade between the primary tumor and liver metastatic lesions.”
Disclosure: For full disclosures of the study authors, visit journals.lww.com/ajsp.
