Identifying breast cancer patients most likely to benefit from Aromatase Inhibitor Therapy after adjuvant radiation and Tamoxifen

Oct 23 2006

While some breast cancer survivors could benefit from adding aromatase inhibitors to the standard five years of tamoxifen, a new study shows the additional therapy should be weighed carefully for each individual.

Writing in the December 1, 2006 issue of CANCER, a peer-reviewed journal of the American Cancer Society, the study's authors say potential improvement in cancer-free survival beyond 5 years with the added therapy may be less than 2 percent for most patients.

For decades, clinicians have given breast cancer patients tamoxifen, which has been shown to improve survival when given for five years. More recently, aromatase inhibitors, another class of estrogen modulating drugs, have been used to prevent estrogen formation. A large randomized study has shown that use of aromatase inhibitors after tamoxifen may further improve survival and is recommended for postmenopausal women. Led by Gary M. Freedman, M.D. of the Fox Chase Cancer Center in Philadelphia, researchers investigated which sub-groups of breast cancer patients treated with tamoxifen may benefit the most from this extended therapy with aromatase inhibitors.

The researchers found that in this study population of 471 women, the potential addition of an aromatase inhibitor would have provided only marginal benefits. Premenopausal women and patients with at least four positive lymph nodes would experience the greatest 10-year cancer-free survival benefits. Patients with none or fewer positive lymph nodes, advanced age, or other medical problems that would limit their life expectancy would not have the same benefit from 5 more years of therapy.

"Based upon our findings," the authors conclude, "women who are premenopausal at the time of initial therapy and patients who have 4 or more positive lymph nodes will have the greatest potential benefit from the addition of extended adjuvant anti-estrogen therapy." For patients over 60 years old, "the decision needs to be individualized based upon their initial nodal status and presence of comorbidities that would reduce their 5-year life expectancy."