Many post-menopausal women take hormonal therapy medicine -- either an aromatase inhibitor or tamoxifen -- after breast cancer surgery and other treatments for hormone-receptor-positive, early-stage breast cancer. Most women usually take hormonal therapy medicine for 5 years. Hormonal therapy can reduce the risk of the cancer coming back (recurrence). Hormonal therapy taken after surgery and other treatments is called adjuvant hormonal therapy.
The study reviewed here found that women who took tamoxifen for 2.5 to 3 years and then switched to the aromatase inhibitor Aromasin (chemical name: exemestane) for 2 to 2.5 years (for a total of 5 years of hormonal therapy) had the same risk of recurrence as women who took Aromasin for 5 years. Other studies looking at other aromatase inhibitors also suggest that starting on tamoxifen and then switching to an aromatase inhibitor after 2 to 3 years is just as good as taking an aromatase inhibitor for 5 years. These results were reported at the 2009 San Antonio Breast Cancer Symposium.
This study, called the TEAM (Tamoxifen Exemestane Adjuvant Multinational) trial looked at 9,766 post-menopausal women diagnosed with hormone-receptor-positive, early-stage breast cancer. When the study started, the women were going to get either tamoxifen or Aromasin for 5 years. But other research suggested that Aromasin was more effective at preventing breast cancer recurrence, so 2.5 to 3 years after starting tamoxifen, those women were switched to Aromasin. The women who were taking Aromasin continued to take that medicine. All the women took hormonal therapy for 5 years.
Early results from the TEAM trial suggested that taking Aromasin for 5 years was better than starting on tamoxifen and switching to Aromasin. Still, as more information was collected the later results reported here showed no differences in outcomes for the two treatments.
Recurrence risk after 5 years was the same for both treatments:
Other benefits also were the same for the two treatments:
Other research has shown that an aromatase inhibitor is better than tamoxifen at reducing the risk of recurrence when the medicines are taken for 5 years, with no switching. Still, for a number of reasons, including side effects and cost, starting on tamoxifen and then switching to an aromatase inhibitor can be a good alternative to taking either tamoxifen or an aromatase inhibitor for 5 years.
Hot flashes and night sweats -- called vasomotor symptoms -- are side effects of both tamoxifen and the aromatase inhibitors, though they're more common with tamoxifen. Hot flashes and night sweats happen because these medicines reduce the amount of estrogen in the body. Joint pain is a more common side effect of the aromatase inhibitors. Doctors aren't sure why aromatase inhibitors can cause joint pain. Tamoxifen is available as a generic medicine, so tamoxifen can be much less expensive than an aromatase inhibitor (depending on insurance coverage).
If you're a post-menopausal woman diagnosed with hormone-receptor-positive, early-stage breast cancer, keep two things in mind when you and your doctor are deciding on a treatment plan:
Ask your doctor about the differences in benefits and side effects between aromatase inhibitors and tamoxifen. You may want to ask if taking the same hormonal therapy for 5 years or switching after 2 to 3 years on tamoxifen makes sense for you. If you're currently taking tamoxifen, ask whether switching to an aromatase inhibitor would be a good idea. Together, you can decide on a treatment plan that is best for YOU.
SAN ANTONIO (MedPage Today) -- Women get the same breast cancer outcomes long term whether they start out on exemestane (Aromasin) or switch to it after a few years on tamoxifen, researchers found.
At five years, exemestane monotherapy yielded nearly identical disease-free survival as was achieved when the aromatase inhibitor was started after two-and-a-half to three years of tamoxifen (85.7% versus 85.4%, P=0.604), Daniel Rea, MD, of the University of Birmingham in England reported here at the San Antonio Breast Cancer Symposium.
Gone were the modestly better outcomes with exemestane seen at the 2.75-year analysis reported at the same meeting last year.
These results from the TEAM (Tamoxifen Exemestane Adjuvant Multinational) trial revealed no trace of superiority for any secondary endpoint either, according to Rea and his colleagues.
"The bottom line in interpretation of this is by the time you've got to five years," the outcomes are the same, Rea said at a press conference.
This largely fits with the results of other trials comparing upfront aromatase inhibitors to tamoxifen and an aromatase inhibitor in sequence, he said.
In BIG 1-98, also reported at last year's SABCS, five years of letrozole was superior to five years of tamoxifen but the numerical trend for lower recurrence compared with tamoxifen followed by letrozole was not statistically significant (9.1% versus 7.3% at five years).
Expectations fell on both sides of the fence, noted press conference moderator Edith Perez, MD, of the Mayo Clinic in Jacksonville, Fla.
"For postmenopausal women there had been hope that the five years of aromatase inhibitor were going to be better than using the what is now a little less expensive tamoxifen for a little while and then going to the aromatase inhibitor," she said at the press conference. "Other people actually projected the opposite. What this study is showing us is that there are options."
TEAM was the first trial to compare the sequential strategy to five years of aromatase inhibition using exemestane.
The open-label study initially randomized postmenopausal women with early-stage invasive tumors expressing receptors for estrogen, progesterone, or both to receive once daily tamoxifen (20 mg) or exemestane (25 mg) for five years.
After the Intergroup Exemestane Study revealed better outcomes for patients who switched from tamoxifen to exemestane, a protocol switched all tamoxifen-group women to exemestane after 2.5 to three years.
With additional enrollment, the 9,766 women in the trial were followed through a median 5.1 years of treatment.
Metastases accounted for more than half of the disease-related events during this period.
Among the secondary outcomes Rea reported, the trial showed:
Adverse events were as would be expected with the two agents, more heavily weighted toward the typical tamoxifen profile in the sequential therapy arm and with higher incidence of the aromatase inhibitor-associated side effects in the upfront exemestane group, Rea said.
There was a numerical excess of endometrial pathology with the tamoxifen/exemestane switch, including endometrial cancer (17 versus seven with exemestane alone, P=NS), he noted.
"So you've got a different toxicity profile to chose between these two drug strategies," he concluded. "Both of these strategies appear to be reasonable approaches for patients with hormone receptor positive cancer. The choice of which agent you're going to use is going to be based on toxicity profile more than efficacy."
The researchers acknowledged that, as an open-label study, the statistical waters were muddied by off-protocol crossover.
Rea said his group is now looking at biomarkers in these patients to tease out if certain subgroups of patients benefit more from one strategy or the other.
The study was supported by Pfizer.
Rea reported being an adviser to and serving on the speakers' bureau for Novartis, AstraZeneca, and Pfizer and having research funding from Novartis and Pfizer.
Co-authors reported conflicts of interest with the same three companies, including two as employees of Pfizer.
Perez reported serving on the steering committee for sorafenib (Nexavar) and for a Genetech trial and serving on an independent monitoring committe for Novartis, all without direct funding from the companies.
Primary source: San Antonio Breast Cancer Symposium Source reference: Rea D, et al "Five years of exemestane as initial therapy compared to 5 years of tamoxifen followed by exemestane: The TEAM Trial, a prospective, randomized, phase III trial in postmenopausal women with hormone-sensitive early breast cancer" SABCS 2009; Abstract 11.
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