Radioimmunodetection of human colorectal cancers by an anti-tumour monoclonal antibody.

In 10 out of 11 patients with colorectal cancer radiolabelled antitumour monoclonal antibody (791T/36) was localised to the tumour. The mean tumour to non-tumour uptake ratio of antibody demonstrated by imaging with a gamma camera was 4.4/1 after subtraction of background radioactivity. The antibody did not localise in one patient who had received radiotherapy to his tumour two weeks previously. In 5 patients with primary neoplasms localisation of the antibody was confirmed by further imaging of the resected specimens and in-vitro radioactivity counting of the tumour and comparison with the activity in adjacent normal colon.