According to the biodistribution results in normal mice (pIgA-SH higher uptake in the caecum), biodistribution studies of 99mTc-anti-CEA pIgA-SH at 4 h and 8 h were performed in a mouse CRC orthotopic graft model (Table 4) and compared with irrelevant IgA (99mTc-anti-peanut pIgA-SH) and healthy nude mice to evaluate the in vivo CEA affinity of IgA. Here, CEACAM5 is linked to colorectal carcinoma.