Mono-centric, observational, prospective study, designed for pts with diagnosis of hormone-positive breast cancer to evaluate the correlation between the response to hormonal treatment indicated by the reduction of the level of Ki67 and miRNA100 in two groups of patients

The potential role of miRNAs will be studied as a predictor of hormone sensitivity in hormone-positive breast carcinomas. The miRNA100 obtained on biopsy will be compared with the expression levels of those obtained from the surgically removed tumor, in order to assess the possible modulation of miRNA100 following hormonal treatment.

Inclusion Criteria:

• Ability to provide written informed consent
• Age greater than 18 years
• histological diagnosis of invasive carcinoma of the breast
• X-ray evidence (mammography and / or ultrasound) strongly suggestive for the presence of invasive breast cancer (BIRADS 4c or BIRADS 5) of greater than 15mm diameter.
• Carcinoma stage I (if diameter> 15 mm) or II, unresectable, or
• Carcinoma in stage II or III, operable as a result of presurgical therapy, or
• Carcinoma in IV debut stage, asymptomatic, with primary operable breast cancer, or as a result of presurgical therapy
• Positivity for the estrogen receptor and / or to the progestin defined as the expression of one or both hormone receptors in ≥10% of tumor cells
• Negativity for HER2
• Cell proliferation, defined as the percentage of Ki67 positive tumor cells,> 5% (corresponding to a value of 1.79 after log-normal transformation)
• Postmenopausal status
• Ability to take an oral therapy, in the absence of malabsorption syndrome known, previous stomach surgery or the small intestine
• Ability to perform the staging examinations and screening provided for in the
• Protocol
• Eastern Cooperative Oncology Group (ECOG) = 0
• The patients will have a normal bone marrow function, liver and kidney

Exclusion Criteria:

• Previous treatment for breast cancer with chemotherapy, lapatinib, trastuzumab, letrozole, anastrozole, exemestane or tamoxifen.
• Other cancers diagnosed in the last five years, with the exception of basal cell or squamous cell carcinoma of the skin, melanoma in situ or cervical cancer in situ.
• Premenopausal
• Known hypersensitivity to letrozole or to any of its excipients (for example: women with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or mal absorption of glucose / galactose).
• Evidence of a severe and poorly controlled systemic disease affecting the lung, heart, liver, kidney that may compromise adherence to treatment or an extended follow-up.
• Inflammatory bowel disease not controlled (eg Crohn's disease, ulcerative colitis).
• Active infection and / or inadequately controlled.
• Alteration of mental status, dementia, or any psychiatric condition that might impair the ability to consciously sign the informed consent.
• Breast cancer triple negative, or negative for both HER2 overexpression for the expression of hormone receptors.

post menopausal hormone-positive breast cancer patients