Only in patients with hormone‐dependent breast infiltrating ductal carcinomas, CA15.3 serum levels are inversely correlated with the immunohistochemical expression of Bcl2

ObjectiveTo study possible association between serum CA15.3 levels and immunohistochemical expression of Bcl2 in women affected by infiltrating ductal breast carcinomas.Materials and methodsTwo hundred and fifty consecutives women with breast infiltrating ductal carcinomas, aged between 37 and 83 years were included in this study. Serum CA15.3 was determined by electro-chemoluminescence assay (ECLIA-Elecsys 170 Roche). Immunohistochemical staining on tissue sections of 4–5 microns was done by the EnVision method with a heat-induced antigen retrieval step. Antibody used for Bcl2 was (124, Dako, dilution 1/150). Bcl2 expression was assessed as negative (−), weak positive (+) or strong positive (++).ResultsIn the study group, serum CA15.3 concentrations ranged between 1 and 1743 U/ml, with 25, 50 and 75 percentiles of 12.7, 17.6 and 24.3 U/ml respectively. Serum CA15.3 concentrations were higher in Bcl2 negative cases than in Bcl2 + and Bcl2 ++. We found statistically significant differences between subgroups Bcl2 negative and Bcl2 ++ (p = 0.044), between Bcl2 + Bcl2 ++ (p = 0.039) and between Bcl2 ++ and Bcl2 −/+ (p = 0.013). When we considered 25 U/mL as the threshold of positivity, antigen values > 25 U/ml were more frequent in tumors Bcl2 − than in Bcl2 ++ (20/52 vs 29/170, p = 0.001). The same behavior was observed when comparing the subgroups −/+ with ++ (p = 0.001). A very important aspect of our work was that this CA15.3 behavior in relation to the immunohistochemical expression of Bcl2 was maintained in hormone-dependent tumors (ER +), but not in hormone-independent ones.ConclusionsThe results led us to the following consideration: In women affected by infiltrating ductal breast carcinomas, serum levels of CA15.3 associated inversely, both qualitatively and quantitatively, with the immunohistochemical expression of Bcl2, but this fact exists only in hormone-dependent tumors.

► Inverse association between serum CA15.3 and Bcl2-immunohistochemical expression.
► This relationship only exists in cases with high expression of ER.
► Bcl2 is a useful prognostic and predictive factor in breast cancer.
► Relationship between Bcl2 and CA15.3 could help to explain their clinical usefulness.