New study explores letrozole's effects on breast cancer before surgery

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Histologic documentation of invasive breast cancer by core needle or incisional biopsy. Subjects without excess baseline tumor tissue are eligible and evaluable for Primary Objective #2 (re: adherence). Excess baseline biopsy tumor tissue sufficient to make ten 5- micron sections must be available for research use for a subject to be evaluable for Primary Objective #1 (re: molecular analyses). 2. The invasive cancer must be estrogen receptor alpha (ER)-positive, with ER staining present in greater than 50% of invasive cancer cells by IHC. 3. The invasive cancer must be HER2-negative (IHC 0-1+, or with a FISH ratio of \<1.8 if IHC is 2+ or if IHC has not been done). 4. Clinical Stage I-III invasive breast cancer with the intent to treat with surgical resection of the primary tumor. Baseline tumor must be ≥0.5 cm. For the optional research biopsy (from 5 subjects), tumor must be ≥1 cm. 5. Patients with multicentric or bilateral disease are eligible if the subject is a candidate for clinically indicated neoadjuvant endocrine therapy. Samples from all available tumors are requested for research purposes. 6. Women over 18 years of age, for whom (A) neoadjuvant treatment with an aromatase inhibitor would be clinically indicated, and (B) adjuvant treatment with one of the following would be clinically indicated: tamoxifen; anastrozole; letrozole. Women must be postmenopausal, defined as last menstrual period \>2 years prior to registration, or \>1 yearer prior to registration with FSH and estradiol in post-menopausal range. 7. Patients must meet the following clinical laboratory criteria: * Absolute neutrophil count (ANC) ≥ 1,000/mm3 and platelet count ≥ 75,000/mm3. * Total bilirubin ≤ 1.5 x the upper limit of the normal range (ULN). * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 x ULN. 8. Ability to give informed consent. Exclusion Criteria: 1. Prior endocrine therapy for any histologically-confirmed cancer or prevention of breast cancer in the last 10 years is not allowed. 2. Any other neoadjuvant therapy for breast cancer. Bisphosphonate or denosumab treatment for metabolic bone issues are allowed. 3. Women who are pregnant or lactating.