Do Aromatase Inhibitors (AIs) Decrease Intestinal Calcium Absorption?

Research Question: Do Aromatase Inhibitors (AIs) Decrease Intestinal Calcium Absorption?

Study Design: Up to 10 post-menopausal women with early stage breast cancer initiating an AI
as adjuvant therapy will participate in this two-month study. The primary study outcome is
the change in intestinal calcium absorption following AI therapy. Secondary outcomes are the
changes in bone resorption markers and musculoskeletal signs and symptoms after initiation
of therapy.

We will interview women and review their medical records to determine eligibility. Eligible
subjects will undergo two CTRC studies. The first study will determine their baseline
calcium absorption, and the second study will occur after taking an AI daily for at least 6
weeks. Women will present to the CTRC in the early morning and receive an oral and
intravenous stable calcium tracer with breakfast. Over the next 24 hours, we will collect
all urine for measurement of its calcium content. During each inpatient stay, we will assess
musculoskeletal symptoms by questionnaire and joint examination. Each woman will complete a
four-day diet diary twice during the study.

Major Risks: The study confers no major risks. We describe minor risks in the protocol and
consent form.

Potential Benefits: Subjects receive no direct benefits from the study. Information on how
AIs affect calcium absorption is of great import, as AIs are standard therapy in
post-menopausal women with breast cancer and often cause bone loss.

Consent Procedure: Interested subjects will receive a verbal description of the study along
with the consent form and HIPAA document. We will answer all subjects' questions regarding
the study. Consenting volunteers will receive a copy of the consent form and HIPAA
documents.