A 2-year experience with a computerized in vitro assay of leukocyte adherence inhibition (LAI) indicated that patients with
cancer of either the colorectum, stomach, pancreas, breast, or lung expressed antitumor immunity to an organ-type specific neoantigen. About 1% of the 1,299 control subjects with benign or malignant disease had a positive LAI assay and 2.5% of patients with inflammatory disease of the colorectum, stomach, pancreas, or lung had a positive LAI assay when tested against
tumor extracts of the same organ. Of the 351 patients with
cancer of either the colorectum (111), stomach (40), pancreas (28), lung (57), or breast (116) who harbored a microfocus of
cancer, 80% or more were LAI positive. As the stage of the
cancer advanced, fewer patients were LAI positive. Nine of 45 patients (20%) with colon
adenomas had a positive LAI response to
colon cancer antigen and 17 of 204 patients (8%) with benign
breast disease reacted to the
breast cancer antigen. Our results suggested that the leukocytes of some of the LAI-positive patients with either colon
adenomas or benign
breast disease were responding to an
organ-specific neoantigen. Whether the acquisition of a cell surface
tumor antigen by the colon
adenomas and the dysplastic lesions of the breast implies an irretrievable step to ultimate
malignancy is unknown. Most patients exhibit a vigorous antitumor immune response when the
cancer exists as a microfocus, and some even before the
neoplasm has acquired the capacity to invade.