Objective: To study possible association between serum CA15.3 levels and immunohistochemical expression of Bcl2 in women affected by infiltrating ductal breast carcinomas.
Materials and methods: Two 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 (++).
Results: In 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.
Conclusions: The 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.
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