ABSTRACT
The goal of preoperative pharmacotherapy in patients with breast cancer is to enable breast conserving surgery in stage T3N0-1M0 or radical mastectomy in patients with primary inoperative tumors (T1-4N0-3M0). The choice of optimal treatment should be based not only on risk factors resulting from the stage but also on predicted cancer responsiveness to the treatment. The breast cancer subtypes defined by immunohistochemical profile (expression of ER, PR, HER2 and Ki67) are characterized by different responsiveness to therapy. Complete response confirmed by histopathological evaluation after neoadjuvant chemotherapy is a positive prognostic factor in some breast cancer subtypes. This marker is not of value in postmenopausal patients with ER/PR+ HER2- tumors, who are candidates for neoadjuvant hormone therapy. These patients have a good prognosis if in a histopathological report after surgery there are features such as pT1, pN0, Ki67 < 3%, and ER Allred score ≥ 3. The goal of the paper is to present current knowledge about preoperative pharmacotherapy of breast cancer.
ABSTRACT
BACKGROUND: HER2 overexpression is an unfavorable prognostic factor in patients with breast cancer, but it is also a target for the monoclonal antibody trastuzumab, which is effective in adjuvant and palliative settings. HER2 positivity is an inclusion criterion for immunotherapy, but it is not a positive predictive factor, and only half of patients benefit from the treatment. AIM: The aim of this study was to evaluate the prognostic and predictive value of HER3, PTEN and phosphorylated HER2 (p-HER2) expression in primary breast tumors of patients treated with trastuzumab in an adjuvant or palliative regimen. MATERIAL/METHODS: Immunohistochemical (IHC) analysis with 3 antibodies specific to the proteins was performed in tumor specimens obtained from 81 HER2-positive patients treated with trastuzumab. RESULTS: HER3 overexpression was present in 55.6% of the examined tumors, and PTEN or pHER2 positivity was present in 32.0% and 34.6% of them, respectively. HER3 overexpression and PTEN positivity correlated with larger tumor size (p=0.016 and p=0.008, respectively). p-HER2 positivity correlated with more advanced clinical stage of the disease (p=0.032). There was no correlation between the proteins' expression and survival for 31 patients treated with trastuzumab in the palliative regimen. DISCUSSION: HER3 overexpression, PTEN positivity and p-HER2 positivity in tumor cells of HER2-positive patients correlate with more advanced clinical stage of breast cancer. Expression of these proteins does not predict outcome of trastuzumab treatment.
