Correlation of PD-L1 staining between primitive tumor and metastasis in advanced colorectal cancer patients

Background: Up to now, published studies have failed to demonstrate a predictive role of PD-1 or PD-L1 immunostainings in metastatic (met) colorectal cancer (mCRC) patients (pts) submitted to immunotherapy. However, in mCRC as well as in other solid tumors there is great interest on the description of concordance of expression between different sites of disease in the same pt. As data on receptor positivity are more easily obtained from...