Section 5
Clinical Use of Aromatase Inhibitors

USE AS FIRST-LINE ENDOCRINE THERAPY OF METASTATIC BREAST CANCER

I’m using aromatase inhibitors first-line. The data for response rate and time to progression are very compelling that these agents are as good if not better than tamoxifen in ER-positive patients. They also don’t have the thromboembolic risk, which is small but substantial with tamoxifen,and they’re very user-friendly. Plus, a lot of women are concerned about tamoxifen use — sometimes inappropriately — and the aromatase inhibitors are much less threatening. So, I’m using these agents in those patients.

We are all also very excited about the ATAC adjuvant trial — anastrozole, tamoxifen or the combination. The study has accrued more than 9,000 patients, and to my knowledge, it’s the largest randomized trial in early -stage breast cancer that’s ever been done. There hopefully will be some preliminary data available this year. This is very exciting — to look at anastrozole up front as adjuvant therapy in postmenopausal patients.

—Hyman Muss, MD

AROMATASE INHIBITORS AS ADJUVANT THERAPY WHEN TAMOXIFEN IS CONTRADICTED

There are select patients for whom SERMs — whether it’s tamoxifen or toremifene — are contraindicated. Certainly, there are people for whom there might be a compelling reason to use adjuvant endocrine therapy — those with multiple nodes, a large tumor — but for whom you’re still concerned about the side effects of tamoxifen such as in patients with a history of DVT or those taking anticoagulants.

I think the data are so good in postmenopausal patients with metastases that,short of seeing the ATAC trial data, it’s reasonable to use an aromatase inhibitor in these cases, And I have done it in several patients. I think you should tell the patient that these drugs are not FDA-approved as adjuvant therapy, but there hasn’t been one study that didn’t fall in a positive direction of the aromatase inhibitor being better than tamoxifen in metastastic disease.

—Hyman Muss, MD

We rarely use aromatase inhibitors in the adjuvant setting, but I do have a few postmenopausal patients who have really struggled to tolerate tamoxifen who clearly said, “I just can’t take this for five years.” Then I think it’s very reasonable to switch them to an aromatase inhibitor instead of being on no hormonal therapy, which would be the alternative in that situation.

I’ve also had a couple of patients who had significant coronary artery disease, previous thrombotic stroke and are on chronic anticoagulation because of those problems. And then I think it would also be reason-able to think about an aromatase inhibitor. Other than those situations, we’ve not used adjuvant aromatase inhibitors except in a trial setting.

—Kathy M i l l e r, MD

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