Although there is data suggesting the in vitro inhibition of
aromatase in cell lines by
antidiabetic biguanide metformin (MF), there is no data on the intratumoral
breast cancer (BC)
aromatase expression in patients already receiving
therapy for type II diabetes. Paraffinized
tumor samples obtained from 57 BC pts aged 48-77 yrs, >80% of pts had stage T1-2N0-3M0 BC. Thirteen of the pts didn't have diabetes, 44 pts were previously diagnosed type II diabetes and reseaved the following
therapy for at least 1 year: diet only (n=14), sulphonylurea (SU, n=14),
metformin (MF, n=9) or MF with SU (n=7).
Tumor samples were deparaffinized in
xylene and treated with the monoclonal
aromatase antibody 677. The rate and intensity of tissue staining was then analyzed by semi-quantitative method using conventional scores. Negative controls were processed with 0.01 M PBS instead of the specific antibody. For positive control
paraffin-embedded human placenta samples were used. By conventional scores method the following values were obtained: 1.31 (pts without diabetes), 1.47 (all diabetic patients), 2.22 (MF), 1.50 (SU), 1.29 (MF+SU), 1.81 (MF and MF+SU), 1.07 (diet). Allred scores for
progesterone receptor (PR) were the highest in the samples from pts treated with MF or MF+SU and the lowest in the samples obtained from SU-treated pts. Thus, in contrast to previous findings suggesting the suppressive effect of MF on
aromatase in vitro, no such trend was discovered for
aromatase expression in
tumor samples from diabetic patients treated with MF. Although the investigated patients population is still small, this data combined with clinical data (higher PR levels) may suggest the better responses to hormonal
therapy in MF-treated diabetic patients.