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. Hormonal therapy can reduce the risk of the cancer coming back (recurrence). Hormonal therapy used in this way is called adjuvant hormonal therapy.
The aromatase inhibitors are:
Most women take adjuvant hormonal therapy for 5 years.
The American Society of Clinical Oncology (ASCO) has issued new guidelines on adjuvant hormonal therapy medicines. ASCO is a national organization of oncologists and other cancer care providers.
The new ASCO recommendations for adjuvant hormonal therapy treatment for post-menopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer are:
An aromatase inhibitor is preferred overtamoxifen. This recommendation is supported by a number of studies showing that women treated with an aromatase inhibitor are somewhat less likely than those treated with tamoxifen to have the cancer come back.
Most women should take adjuvant hormonal therapy for a total of 5years. Options include:
While not routine, some women may benefit from taking adjuvant hormonal therapy for 8 to 10 years (called extended adjuvant therapy). In these cases, ASCO recommends 5 years of tamoxifen followed by 3 to 5 years of an aromatase inhibitor.
ASCO doesn't recommend one aromatase inhibitor over another -- they're considered interchangeable. If side effects from one aromatase inhibitor are intolerable, switching to a different aromatase inhibitor rather than tamoxifen may make sense.
ASCO didn't recommend routine genetic testing for the CYP2D6 enzyme when deciding which hormonal therapy medicine to use. The body uses the CYP2D6 enzyme to turn tamoxifen into its active form. Women who make low levels of this enzyme may not get all the benefits of tamoxifen treatment.
ASCO recommends that pre-menopausal women take only tamoxifen as adjuvant hormonal therapy.
Research shows that aromatase inhibitors are generally somewhat better than tamoxifen for reducing the risk of recurrence in post-menopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer. Still, for a number of reasons, including side effects and cost, tamoxifen may be a better choice for some women.
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. Joint pain is a more common side effect of the aromatase inhibitors. Both tamoxifen and the aromatase inhibitors can cause serious side effects. Treatment with either tamoxifen or an aromatase inhibitor can lead to dangerous blood clots in rare cases. This complication is more common with tamoxifen. Also, aromatase inhibitors can weaken bones and make women more likely to break a bone.
Tamoxifen and Arimidex are available as generic medicines, so these may be much less expensive than the other two aromatase inhibitors (depending on your insurance coverage).
If you're a post-menopausal woman who's been diagnosed with hormone-receptor-positive, early-stage breast cancer, keep two things in mind when you and your doctor are deciding on an adjuvant hormonal therapy plan:
Ask your doctor about the differences in benefits and side effects between aromatase inhibitors and tamoxifen, as well as the pros and cons of monotherapy vs. sequential therapy.
If you're already taking tamoxifen, ask your doctor if switching to an aromatase inhibitor would be a good idea. Together, you can decide on a treatment plan that's best for YOU.
(MedPage Today) -- Aromatase inhibitor therapy should be considered for all postmenopausal women with hormone receptor-positive breast cancers, the American Society of Clinical Oncology reemphasized.
An update to their guidelines on adjuvant endocrine therapy again supported the aromatase inhibitors, saying they provide better disease-free survival than tamoxifen (Nolvadex) in this patient population.
But what strategy to use them in -- upfront as monotherapy or sequential after two to three years of tamoxifen -- remains unresolved, according to the update committee led by Harold J. Burstein, MD, PhD, of the Dana-Farber Cancer Institute in Boston.
ASCO has recommended an aromatase inhibitor for these patients since 2004, but provided no guidance on the optimal duration until now.
The update, published online in the Journal of Clinical Oncology, recommends no more than five years' duration for aromatase inhibitors.
If sequential therapy is the strategy used, the available evidence supports an aromatase inhibitor after two or three years of tamoxifen for a total of five years of adjuvant endocrine therapy.
If patients discontinue initial aromatase inhibitor use before the full five years, tamoxifen can be considered for the remainder of the five years.
If an extended strategy of up to 10 years of total endocrine therapy is used, the order should be five years of tamoxifen followed by three to five years of an aromatase inhibitor, according to the guidelines update.
The aromatase inhibitors appear to be interchangeable such that patients who can't tolerate one may be advised to consider not only tamoxifen but another aromatase inhibitor, Burstein's group wrote, noting this was their clinical opinion without randomized trial evidence.
The choice of when and whether to use an aromatase inhibitor for an individual patient may depend on the distinct adverse effect profiles of tamoxifen and aromatase inhibitors and patient preferences, the update writers acknowledged.
Aromatase inhibitors aren't less toxic or better tolerated than tamoxifen, rather "both drug classes have distinct adverse event profiles that are relevant to individualizing therapy for patients," according to the update.
The newer class appears to increase serious cardiac disease incidence, though by less than 1% compared with tamoxifen, as well as high cholesterol, hypertension, bone mineral density loss, fracture, uterine cancer, benign endometrial pathology, hysterectomy, and vaginal discharge.
Tamoxifen, on the other hand, raises venous thromboembolic event risk by 1% to 2% compared with the aromatase inhibitors and is associated with more hot flashes.
The advantage in reducing risk of recurrence with the aromatase inhibitors in absolute terms is modest, "typically amounting to less than 5% through multiple years of follow-up," and without any difference in overall survival, Burstein's group wrote in the guidelines.
For the systematic review, they reviewed 12 prospective, randomized trials of adjuvant aromatase inhibitor or tamoxifen use in different strategies -- initial, sequential, or extended therapy after five years of treatment with adjuvant tamoxifen.
The evidence didn't support using any markers to determine who would benefit most from which strategy, the researchers noted. They specifically recommended against use of CYP2D6 genotype to select adjuvant endocrine therapy.
The only important factor is menopausal status.
Women who are pre- or perimenopausal at the time of breast cancer diagnosis should only get tamoxifen, the guideline update cautioned.
Burstein disclosed that he had no finanical conflicts of interest. Coauthors reported consultant or advisory roles with Pfizer and Novartis; honoraria from Novartis, Astra Zeneca, and Pfizer; and research funding from Novartis and Pfizer.
Primary source: Journal of Clinical Oncology Source reference: Burstein HJ, et al "American Society of Clinical Oncology Clinical Practice Guideline: Update on adjuvant endocrine therapy for women with hormone receptor–positive breast cancer" J Clin Oncol 2010; DOI: 10.1200/JCO.2009.26.3756.
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