Fempro (letrozole) is an aromatose inhibitor most commonly used to prevent or treat breast cancer in post-menopausal women. Less commonly it is sometimes used in pre-menopausal women to treat metastasis or when other medications, such as tamoxifen, are no longer producing good results or are unsuitable for some reason.

Though relatively rare, Fempro is sometimes used as a fertility treatment, and may be given as a pre-treatment prior to terminating a pregnancy.

This product is known to cause harm to unborn or breastfeeding babies. Pre-menopausal women are advised to take a pregnancy test prior to starting treatment. If pregnancy occurs while Fempro is being taken, speak with a doctor about the best course of action.

How Fempro Works

Fempro inhibits the body's production of the hormone estrogen, which, in post-menopausal women, primarily occurs in the breasts as well as certain parts of the brain. In pre-menopausal women the bulk of estrogen production takes place in the ovaries, and it is produced in significantly higher levels than in post-menopausal women; Fempro is rarely used in pre-menopausal women as it does not sufficiently inhibit estrogen production in the ovaries.

Many types of breast cancer are hormone receptor positive cancers, meaning they're stimulated to grow and spread when estrogen is present. Women who take Fempro lower the amount of estrogen in the body, which in turn deprives the cancer, causing it to be unable to continue growing. In some cases it may even shrink the cancer. Note that not all breast cancers are hormone receptor positive; some types call for different treatment.

Women taking Fempro, including post-menopausal women, should take care to avoid consumption of estrogen through other products; doing so can dramatically reduce Fempro's effectiveness. Commonly encountered products include:

• Estrogen creams or lotions
• Certain foods such as soy products and flax seeds
• Birth control pills
• Hormone replacement therapies
• Certain health supplements

A doctor should go over the risks of estrogen supplementation and can provide a more in-depth list of commonly encountered products according to a patient's lifestyle and location.

Treatment Overview

Fempro comes in tablets; most patients take one tablet per day. Food is optional but a full glass of fluid is recommended with each dose. Therapy often lasts for two to five years.

Treatment with Fempro may start in a variety of circumstances:

• As a preventive measure in women at high risk of developing breast cancer
• To enhance effectiveness of other cancer treatments
• Other cancer treatments have stopped producing results
• The cancer has not responded to other cancer treatments
• To inhibit metastasization (spread) of the cancer

Dosage and duration of treatment will vary to some extent depending on a number of factors, including the exact condition being treated, patient response to treatment, and other medications being taken, to name a few.

Fempro is often prescribed following a few years of treatment with tamoxifen, as tamoxifen can lose effectiveness after two to five years. Likewise Fempro can lose effectiveness, in which cases patients are typically switched to tamoxifen.

Side Effects

Most side effects associated with Fempro are not serious, and often stop occurring as the body adjusts to the medication. Some can be difficult to distinguish from menopausal symptoms, as both are caused by a reduction of estrogen. The following are not cause for concern unless severe enough to be disruptive:

• Frequent or worsening headaches
• Night sweats or hot flashes
• Edema (swelling of hands or feet)
• Persistent nausea or stomach pain
• Rapid weight loss or gain
• Extreme fatigue

Long term use of Fempro may increase risk of developing osteoporosis, which increases risk of bone fractures or breaks. Women may want to consider having regular bone density tests performed for the duration of treatment.

Interaction with other medications are always a possibility, and may reduce effectiveness or cause serious side effects. Speak with a doctor before adding, removing, or changing another medication while taking Fempro, including over-the-counter medications, vitamins, and supplements.