News from SABCS: Aromatase inhibitors are more effective than tamoxifen.
A Thursday morning session on adjuvant hormonal therapy was probably the strongest session held at San Antonio or ASCO on that topic in years, according to Stephen Jones, MD. “There was a repetitive theme,” he said in an interview with CURE. “These treatments work and they are better than treatment with tamoxifen.”
Aromatase inhibitors used to treat breast cancer include Arimidex (anastrozole), Aromasin (exemestane), and Femara (letrozole).
n two separate meta-analyses of studies in which aromatase inhibitors were used as initial monotherapy and studies in which patients were switched to an aromatase inhibitor after two to three years of tamoxifen. The meta-analyses showed significantly lower breast cancer recurrence rates for patients treated with aromatase inhibitors compared to patients treated with tamoxifen.
Results were presented o
According to new data from the BIG 1-98 trial, presented in by Henning Mouridsen, MD, PhD, five years of treatment with Femara reduced the risk of death by 19 percent when compared with treatment with tamoxifen. Some patients on the tamoxifen arm crossed over to receive Femara. The reduced risk of death in these patients was 13 percent compared to those patients who only received tamoxifen.
To determine the most effective approach to minimizing the risk of recurrence, the BIG 1-98 trial compared five years of treatment with Femara with two years of Femara followed by three years of tamoxifen and two years of tamoxifen followed by three years of Femara.
There was no evidence that sequential treatments improved disease-free survival compared with Femara alone, Alan Coates, MD, and colleagues found. On the other hand, after two years initial treatment with Femara, the patients who were switched to tamoxifen “couldn’t be distinguished” from the patients who were treated with Femara for the entire study period, Coates told in an interview. This is important, he said, “because if you need to switch, you can afford to switch.”
The TEAM trial asked whether or tamoxifen works better as adjuvant monotherapy for breast cancer. This was the first analysis of this largest-ever trial of an aromatase inhibitor compared with tamoxifen and included data from nearly 10,000 women. The trial compared the efficacy of Aromasin versus tamoxifen as initial endocrine therapy for five years and found a significant advantage for Aromasin.
Jones presented data from this study after almost three years of follow-up. “Overall, this is good news for our patients,” he told the audience. “The event rate in both groups is quite low.” He continued, “Only 570 breast cancer events have occurred.”
Compliance with therapy during clinical trials is a growing concern, Jones said during his presentation. In the TEAM trial, 29 percent of the patients in the tamoxifen arm and 19 percent in the Aromasin arm trial discontinued treatment. In an interview with , Jones explained that these rates are similar to discontinuation rates seen in other recent large trials.
“The last two or three years, this has really become an issue. In trials where patients are taking tamoxifen, around 40 percent have dropped off the drug before the end of five years.” These high rates of discontinuation make it harder to accurately interpret the results of these studies, Jones said.
“There are a lot of reasons” for noncompliance, he noted. “Sometimes it’s side effects, sometimes it’s cost.” He encouraged physicians to make sure patients are able to comply with therapy. “If there are issues with tolerability, find them another drug that might be better tolerated, because the maximum benefits come when you take the medicine.”
Read more of CURE's coverage of the 31st annual San Antonio Breast Cancer Symposium at http://media.curetoday.com/htmlemail/sabcs.