Aromatase Inhibitors and Their Properties

November 12, 2012

Aromatase Inhibitors and Their Properties

The toxicity connected to AIs (aromatase inhibitors) may be linked to the lack of improved survival when it is compared with tamoxifen.

Aromatase inhibitors are a type of drug which is used in the treatment of breast cancer in women who are postmenopausal. These drugs are given as a substitute to tamoxifen or given after the start of treatment where tamoxifen has been prescribed. AIs are normally associated with a reduction of reoccurrence of breast cancer. But they are not associated with improved survival. The drugs are linked to many unwelcome toxic effects. This is in comparison to tamoxifen.

A study was carried out to examine the toxicity of aromatase Inhibitors against tamoxifen and if this would explain the lack of overall survival benefit in postmenopausal breast cancer patients. Random trials were identified which compared the AIs and tamoxifen in postmenopausal women. A meta-analysis of data from the selected random trials was carried out. The data was gathered from seven trials which involved just over 30,000 patients.

The researchers found that longer use of AIs compared to tamoxifen, was linked to an increase in bone fractures and heart diseases. But they found there were lower risks of cancers of the womb and blood clots. The researchers found no difference in the risks of other forms of cancer or strokes.

It was found that using aromatase inhibitors for a period of two to three years after the first treatment with tamoxifen, there was a reduced risk of death which is not related to the effects of breast cancer. This is compared to using tamoxifen or AIs alone.

The authors of the report found that the toxicity of AIs when they were used for long periods of treatment may be the reason behind the lack of overall survival benefit. The benefits remain to help reduce the risk of cancer of the breast returning.

Editors of this research noted that the doctors, “should choose initial endocrine therapy for the individual patient with careful attention to the risk of breast cancer recurrence, the risk of toxicity, and comorbidities”.

Researchers who were involved say, “The cumulative toxicity of aromatase inhibitors when used as up-front treatment may explain the lack of overall survival benefit despite improvements in disease-free survival. Switching from tamoxifen to AIs reduces this toxicity and is likely the best balance between efficacy and toxicity.”

DoctorsÂ’ from a womenÂ’s hospital state that, “survival benefits with adjuvant tamoxifen were not truly evident until after 5 years of follow-up. Thus, it is conceivable that a late survival advantage with AIs over tamoxifen may also emerge over time.”

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