Tamoxifen and Zoladex (chemical name: goserelin) are hormonal therapy medicines used to lower the risk of breast cancer coming back (recurrence) in premenopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer. The study reviewed here found that tamoxifen and Zoladex work about the same to lower the risk of breast cancer coming back.
Estrogen can make hormone-receptor-positive breast cancers grow. Hormonal therapy medicines treat hormone-receptor-positive breast cancers in two ways:
There are several types of hormonal therapy medicines. Zoladex is a luteinizing hormone-releasing hormone (LHRH) agonist. Zoladex works by stopping the ovaries from making estrogen. Doctors may refer to this as "medical ovarian shutdown." Zoladex is given by injection every 4 weeks. Tamoxifen is a selective estrogen receptor modulator (SERM). Tamoxifen works by blocking the effects of estrogen in breast tissue, including hormone-receptor-positive breast cancers. Tamoxifen is a pill taken by mouth once a day.
More than 2,700 women diagnosed with hormone-receptor-positive breast cancer participated in the ZIPP (Zoladex In Premenopausal Patients) trial. After surgery and other treatments, the women got 1 of 4 treatment approaches to reduce the risk of breast cancer recurrence:
The women were followed for more than 10 years. The results:
Tamoxifen and Zoladex worked about the same to lower the risk of breast cancer coming and improve survival. Compared to women who didn't get either medicine, the risk of breast cancer coming back was 33% lower for women who got 2 years of Zoladex and 29% lower for women who got 2 years of tamoxifen. The difference in recurrence risk reduction between the two medicines wasn't significant, which means it could have been due to chance.
There was no difference in the risk of breast cancer coming back between women who got BOTH tamoxifen and Zoladex and women who got ONLY tamoxifen or ONLY Zoladex. This finding is important because doctors often recommend the medicines be used together to reduce the risk of recurrence.
Zoladex may cause bones to weaken. In this study, researchers looked at a smaller group of 89 women to see if there were any differences in bone strength between the treatment groups. Women who got Zoladex had a 5% reduction in bone mineral density, which means their bones were weaker. Bone mineral density went up after the women stopped taking Zoladex. Women who got both tamoxifen and Zoladex had a 1.4% reduction in bone mineral density. The difference in bone mineral density reduction is likely due to tamoxifen. Tamoxifen can actually strengthen bones in many women.
If you're premenopausal and have been diagnosed with hormone-receptor-positive early-stage breast cancer, you and your doctor will discuss many treatment options to lower the risk of breast cancer coming back after surgery. Hormonal therapy will be one of these options. The study reviewed here shows that either tamoxifen alone or Zoladex alone can be a good option.
For some women with very high risk of the cancer coming back or of a new, second breast cancer, surgically removing the ovaries is another option.
Before you decide on a treatment plan, be sure to talk about all the benefits, side effects, and risks of each option with your doctor. Together you can make the best decision for you and your unique situation.
Visit the Breastcancer.org Hormonal Therapy section to learn more about all the hormonal therapy medicines that can be used to treat breast cancer and lower the risk of it coming back.
LONDON, Feb. 26 (MedPage Today) -- For premenopausal women with early breast cancer, two years of goserelin (Zoladex) was as effective as two years of tamoxifen more than a decade after starting therapy, researchers here said.
But combining the two drugs provided little additional benefit in terms of recurrence and death, Allan Hackshaw, M.Sc., of the Cancer Research UK Trials Centre at University College London, and colleagues reported online in the Journal of the National Cancer Institute.
The findings come from long-term follow-up of the so-called ZIPP (Zoladex In Pre-menopausal Patients) trial, a four-arm randomized controlled trial comparing no endocrine therapy with two years of goserelin, tamoxifen, or both drugs in 2,710 women recruited from August 27, 1987, to March 22, 1999.
Those taking goserelin were given a 3.6-milligram injection every four weeks, while those getting tamoxifen took 20 or 40 milligrams a day.
For this report, median follow-up was 12 years, with 26,545 person-years all told. The primary outcomes were event-free survival (where an event was recurrence, new tumor, or death), overall survival, risk of recurrence, and risk of breast cancer death.
For all those endpoints, goserelin treatment was associated with a significant risk reduction, compared with no treatment. For instance, the hazard ratio for an event was 0.82, with a 95% confidence interval from 0.73 to 0.92, which was significant at P=0.001. The hazard ratio for overall survival was similar, at 0.83, and significant at P=0.013.
When tamoxifen and goserelin were compared to the control group, they each had similar -- and significant -- reductions in all the four endpoints. For instance, the hazard ratio for event-free survival was 0.67 for goserelin, compared with 0.71 for tamoxifen.
On the other hand, women who got both drugs did not do significantly better on any endpoint than women who got only one.
Put another way, the researchers said, 15 years after starting therapy, for every 100 women not given tamoxifen, there were 13.9 fewer events among those who were treated with goserelin than among those who did not get the drug.
And among women who did get tamoxifen, there were 2.8 fewer events per 100 women treated with goserelin, compared with those not treated -- but that reduction was not statistically significant.
The risk of dying from breast cancer was also reduced significantly in women who got goserelin but not tamoxifen: For every 100 such women, there were 8.5 fewer breast cancer deaths compared with those who got neither drug.
There was also a reduction when the drugs were combined -- 2.6 fewer deaths compared with the control group -- but the difference, again, was not statistically significant.
The effects of therapy on bone were not measured in all women in the ZIPP trial, but the effects of two years of treatment with goserelin and tamoxifen on bone mineral density were examined in a subgroup of 89 patients in the Stockholm group.
The reduction in bone mineral density was 5% in the patients treated with goserelin, with partial recovery a year after therapy was stopped, and 1.4% in the patients treated with tamoxifen and goserelin.
The ZIPP trial, the researchers said, is the largest that has investigated a luteinizing hormone-releasing hormone agonist (goserelin) and the only one to compare it simultaneously with tamoxifen or no endocrine therapy.
One limitation of the study for clinical practice is that the two-year course of tamoxifen was shorter than the five years commonly prescribed today. However, the researchers noted, many women stop tamoxifen therapy before the five years are up, so the two-year comparison may be relevant to them.
The study also did not look at the optimal frequency and duration of goserelin treatment and there is some evidence that less frequent injections will have equivalent benefits.
The study received support from Cancer Research UK, the King Gustaf V Jubilee Fund, and AstraZeneca (the manufacturer of goserelin). One author reported financial links with AstraZeneca, but the company was not involved in either the analysis or the writing of the paper, or the decision to publish.
Primary source: Journal of the National Cancer Institute Source reference: Hackshaw A, et al "Moderate long-term effectiveness of adjuvant goserelin in pre-menopausal women with early breast cancer" J Natl Cancer Inst 2009; 101: 341-349.
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