Complete calcification of colorectal liver metastases on imaging after chemotherapy does not indicate sterilization of disease

Summary Background The significance of complete calcification of liver metastases on imaging is unknown. This study was conducted to determine whether complete calcification of liver metastases after chemotherapy, as assessed by imaging, was synonymous with sterilization of disease. Methods Imaging by triphasic contrast-enhanced helical CT scan and abdominal ultrasound showed complete calcification of eight liver metastases in four patients after systemic chemotherapy. All eight completely calcified liver metastases were resected within four weeks of imaging. Histological and surgical findings were analyzed to see whether there was any correlation between radiological and pathological status for completely calcified liver metastases. Results The pretreatment median diameter at initial imaging of the eight liver metastases that became completely calcified after chemotherapy was 24 mm. In all eight resected calcified liver metastases, pathological examination showed the presence of residual viable tumor cells. Most of the tumor volume was occupied by calcification, necrosis and fibrosis; but small discrete islands of viable tumor cells were detected at the periphery of lesions. Conclusions This preliminary study shows that although imaging evidence of complete calcification of liver metastases may be a good indicator of chemotherapy response, it does not imply sterilization of the malignancy.