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• The main purpose of the study is to learn whether or not continuing hormonal therapy with an AI called letrozole for 5 additional years after already taking 5 years of hormonal therapy (which included an AI) can further reduce the chance of breast cancer returning. Letrozole is investigational (still being researched) for use in patients who have already received an AI as part of their 5 years of hormonal therapy. Letrozole is considered “investigational” because it has not yet received approval from the Food and Drug Administration (FDA) or Health Canada for use after 5 years of hormonal therapy which included an AI.
An AI works by interfering with a substance called aromatase that helps to make estrogen. Estrogen is known to promote the growth of hormone receptor-positive breast cancers such as yours. An AI almost completely blocks out estrogen in postmenopausal women. By blocking out the estrogen levels, growth of tumors is blocked and the chance of breast cancer returning is smaller. In this study, you will be given letrozole or a placebo (a pill that looks like letrozole but does not contain any active drug) after 5 years of hormonal therapy. It is important to look at whether or not taking additional letrozole after already taking an AI affects how well letrozole works to continue to reduce the chances of cancer coming back.
• Another reason for doing this study is to find out whether or not taking the drug letrozole after taking 5 years of hormonal therapy that included letrozole (or other AI) causes more thinning of your bones (osteoporosis) which can cause your bones to break more easily. We also want to find out if letrozole increases the chance of heart attack, stroke, and other problems with blood vessels called arteries.
Trial ID: 20 CIRB
Not Accepting Healthy Volunteers