Immunoglobulins intrinsic to colorectal carcinoma: an unfavorable prognostic association with IgM.

Immunoglobulin (Ig) eluates prepared from cell membrane fractions of 50 colorectal carcinomas were found to contain significantly (P less than .001) less IgA and IgM and marginally less IgG than normal colon mucosa. IgA and IgG were present in all tumors, but IgM was present in only 20 of 50 tumors (40%). Small (less than or equal to the median vol) tumors contained significantly (P less than .05) more IgA and IgG per gram tissue than did large tumors. Tumors with a large (greater than the median) proportion of stroma contained more IgG than did those with less stroma. No associations were found between Ig and amount of viable-appearing tumor tissue, necrosis, mucin production, and staging. Patients whose tumors contained measurable amounts of IgM had a significantly (P = .012) shorter survival than did patients without intrinsic IgM (12 and 27 mo at the 75th percentile, respectively). The difference could not be explained by conventional staging.