4. Mib1/Ki-67: Prognosis prediction and treatment planning

expression [92]. Moreover, some data suggest that endocrine resistance may be specific to selective estrogen modulator (SERM) therapy such as tamoxifen and perhaps not to estrogen depletion therapies such as aromatase inhibitors [59, 93]. Furthermore, the response to liganddepleting therapies such as ovarian ablation or aromatase inhibitors is not affected by HER2

HER2 may be associated with either sensitivity or resistance to some chemotherapeutic agents. For example, HER2 positivity is associated with better outcomes in response to adjuvant anthracycline containing regimens in most studies, probably due to the coamplification of HER2 with topoisomerase II, which is the direct target of anthracyclines [94]. Anyway, the combination of trastuzumab and anthracycline has cardiotoxicity concerns, so that an accurate determination of HER2 alterations in breast carcinomas is mandatory. On the other hand, data about the possibile correlation of HER2 positivity with responsiveness to paclitaxel containing

HER2 gene amplification is directly correlated with its mRNA expression and protein levels, and HER2 status can potentially be evaluated at any of these levels. A great number of commercially available testing kits are approved from FDA for the assessment of patients suitable for the treatment whit trastuzumab (humanized mouse 4D5 monoclonal antibody) may be a suitable treatment. Overexpression of the HER2 protein product may be evaluated by Western blotting, ELISA or IHC; overexpression of its mRNA by Northern blotting or RT-PCR, and its gene amplification by fluorescence (FISH), chromogenic (CISH) or silver-enhanced in

FISH is more accurate, reproducible, and robust than IHC [97], but IHC has been more widely used as the primary test for HER2 status because it results quicker, is viewed using a conventional bright-field microscope, permits parallel viewing of tumor morphological features, and stained tissues do not degrade over time [98]. Moreover, automated IHC techniques may

Recommendations for tissue handling as well as preanalytic, analytic, and postanalytic factors in ER/PR testing are also suitable for HER2 testing. Laboratories performing these tests should follow all accreditation requirements, which conform to the 2010 ASCO/CAP recommendations for ER/PR testing, one of which is the initial testing validation [83]. Laboratories are responsible for ensuring the reliability and accuracy of their testing results and should review

The final IHC result is classified as 3+ in the case of a complete circumferential membrane staining in >10% of neoplastic cells, 2+ in the presence of moderate circumferential membrane staining of >10% of neoplastic cells, 1+ or 0 if there is incomplete membrane staining or no staining in >10% of neoplastic cells. A positive result includes the 3+ and the 2+ in the presence

and document external and internal controls with each test and each batch of tests.

overexpression.

chemotherapy are still contradictory [95].

10 Biomarker - Indicator of Abnormal Physiological Process

3.3. Methods for measuring HER2/neu

situ hybridization (SISH) [96].

enable more rapid testing.

of a ISH confirmation [83].

Numerous measures of tumor cell proliferation have been studied over time, including thymidine labeling index, flow cytometry and S-phase fraction, thymidine kinase, cyclins D and E and their inhibitors p27 and p21, topoisomerase IIα, p53, bax, bcl-2, and Ki67, but methodological shortcomings precluded attribution of prognostic or predictive significance to any of these potential markers [99].

The mitotic index, which is one of the three components of the tumor grading assessment, results the strongest prognostic discriminant in node-negative breast cancer, being the most significant predictor of survival, and rendering less significant the other two elements of tumor grading evaluation, pleomorphism and tubular formation [100]. In particular, patients with mitotic index ≥10 should be considered at high risk and be offered adjuvant therapy.

Mib1/Ki-67 is a proliferation index used as both a prognostic and predictive marker, although its widespread use is limited by the lack of standardization of the assay and its interpretation [99, 101]. This marker of proliferation results an independent prognostic factor for DFS, is significantly predictive for responsiveness to both adjuvant chemotherapy and endocrine therapy, and is predictive for pathological complete response in the neoadjuvant setting [102, 103]. In fact, the Mib1/Ki-67 decrease in the post-treatment samples of women who underwent neoadjuvant therapies is a strong independent predictor of better clinical outcomes [104].
