Circulating secretory component in breast neoplasms.

The serum concentrations of IgAp and IgMr associated secretory component (SIgA and SIgM) of 98 patients with neoplasms of the breast were measured. Of the 56 patients with carcinomas, 11 had increased concentrations of circulating SIgM, which was almost twice as sensitive as SIgA as a marker for carcinoma. Concentrations of circulating SIgA and SIgM were independent of expression of secretory component, IgA, and carcinoembryonic antigen (CEA); histological tumour grade; and tumour cell DNA ploidy, whereas a weak correlation between SIgA and SIgM and circulating CEA was seen. The three patients who had liver metastases indicated had particularly high concentrations of circulating SIgA and SIgM, whereas no difference was generally seen between patients with malignancy and those with benign tumours.