Immunohistochemical analysis of GCDFP-15 and GCDFP-24 in mammary and non-mammary tissue.

Background: Gross cystic disease fluid protein (GCDFP)-15, a major constituent protein in breast cysts, is known to be a marker of breast cancer, while the diagnostic value of GCDFP-24, a protein with a molecular weight of 24,000 daltons, has not been determined. The aim of this study was to elucidate the usefulness of GCDFP-24 for the differential diagnosis of breast cancer in combination with GCDFP-15 and to characterize the histologic features of GCDFP-24-positive breast cancer.

Methods: A total of 326 samples including non-neoplastic tissue and benign and malignant tumors from several anatomic sites were examined using commercially available monoclonal antibodies against GCDFP-15 and GCDFP-24.

Results: In non-mammary tissue, GCDFP-15 was detected in skin, salivary gland, bronchial gland, prostate and seminal vesicle, and GCDFP-24 was detected in apocrine glands and peripheral nerve. Thirty-seven (44.6%) and 22 (26.5%) samples of 83 breast cancers were positive for GCDFP-15 and -24, respectively. Combined assays of GCDFP-15 and -24 raised the positive rate to 50.6%. The markers were not detected in tumors originating from gastrointestinal tract, bronchopulmonary structures or the genitourinary system. Breast cancers positive for both GCDFP-15 and GCDFP-24 were of lower histologic grade according to Bloom & Richardson's scoring system (p < 0.05).

Conclusion: Immunohistochemical analysis of GCDFP-24 in combination with GCDFP-15 expression was useful for definitive diagnosis of breast cancers, and the expression of these markers correlated with low grade breast cancer.