This property of PR1A3 accounts for the low false-positive rate of lymph node detection in immunoscintigraphy of colorectal cancers with PR1A3 in patients (Granowska et al, 1989), given that it has been shown that soluble CEA drains into lymphatics and so can become sequestrated into regional lymph nodes in the absence of cancer cells (Kubo et al, 1992). Here, CEACAM5 is linked to colorectal cancer.