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ANNOUNCER: The latest data from a large clinical trial have strengthened earlier findings that a new drug can be effective in fighting breast cancer.
The study compares Arimidex, in a class of drugs called aromatase inhibitors, to a widely-used drug called Tamoxifen, in fighting the recurrence of disease.
The use of aromatase inhibitors, as well as Tamoxifen, is called hormonal or endocrine therapy.
The drugs manipulate levels of the hormone estrogen in the body. Or, they interfere with estrogen's effect on certain cells. Either approach can curb the growth of many breast cancers.
AMAN BUZDAR, MD: The data which we have now from this large multinational study, it clearly demonstrates that Arimidex or anastrozole has better odds of keeping the woman free of cancer, compared to the woman who is on tamoxifen.
ANNOUNCER: The study is known as "ATAC" -- for Arimidex and Tamoxifen Alone or in Combination. Participants in the study are all post menopause, for those are the only women who should be prescribed aromatase inhibitors.
GENEROSA GRANA, MD: It involved over 9,000 women treated in 28 countries. So it really is a world-wide effort looking at the treatment of early stage breast cancer.
ANNOUNCER: The ATAC trial focused on what is called "adjuvant therapy." That's treatment to help guard against recurrence of cancer following surgery to remove a tumor.
WILLIAM GRADISHAR, MD: Depending on the size of the tumor or whether or not lymph nodes are involved, we make some estimate as to what the risk is going forward. Meaning in the future, that the woman might develop a recurrence of her disease. And if that level of risk is high enough, we generally will recommend what's called adjuvant therapy. That can take the form of chemotherapy, it can take the form of hormone therapy or endocrine therapy, or both.
ANNOUNCER: The ATAC study examined women whose breast cancer cells contained receptors for the hormones estrogen and progesterone, or either of them alone. Only in those types of cancer can hormonal therapy be effective.
HYMAN MUSS, MD: Estrogen is very important in those hormone receptor-positive breast cancers as a stimulator for tumor growth; perhaps for the cancer cells even to spread. And so what it means to the physician taking care of the patient is if he can do something about the estrogen -- like block them with drugs like tamoxifen, which block the effects of estrogen in breast cancer cells, or aromatase inhibitors, which lower the level of estrogens and that's what cut off that food supply. By manipulating that estrogen -- either lowering it or blocking it, we can kill the cancer cells.
ANNOUNCER: Between 40 and 80 percent of women with breast cancer have the type with hormone receptors, depending on the woman's age.
Preliminary results from the ATAC trial showed Arimidex was safe and effective in treating these cases, in post menopausal women. The latest data reinforce those findings.
AMAN BUZDAR, MD: Now we have more mature, updated analysis. Now we have these women who have been followed, on the average, about close to four years. We see that similar benefits are maintained, similar safety profile is maintained. If anything, the benefits look more pronounced now than what they looked in the beginning.
ANNOUNCER: No drug, however, is without side effects. And women and their doctors must consider them carefully in choosing among hormonal therapies.
GENEROSA GRANA, MD: Arimidex appears to be superior to tamoxifen when it comes to a decrease in hot flashes and night sweats; a decrease in weight gain, although slight; a decrease in uterine cancer risk; vaginal bleeding and vaginal discharge; a decrease in clotting risk and that means both lower extremity clots, pulmonary emboli and stroke; and probably a decrease in cardiovascular events in general.
On the other hand, tamoxifen is superior to Arimidex when it comes to muscle and joint aches and pains. Tamoxifen is superior, also, when it comes to a decreased risk of osteoporosis and a decreased risk of bone fractures related to osteoporosis, and this is important, particularly as we're treating a postmenopausal group of women who are not getting hormone replacement therapy for their bone.
ANNOUNCER: In addition to their use after surgery, aromatase inhibitors -- Arimidex along with Aromasin and Femara -- are also being studied for use before surgery, in what's called "neoajuvant" therapy.
GENEROSA GRANA, MD: In Europe, they're quite actively being used for three to four months prior to surgery in larger breast cancers, and they've been shown to shrink the tumor, and often allow for breast conservation for lumpectomy, thus allowing the woman to preserve her breasts rather than having a mastectomy.
ANNOUNCER: In the U.S., doctors most commonly use chemotherapy before surgery to shrink large tumors. But hormonal agents may be used in certain situations.
GENEROSA GRANA, MD: If you have an elderly woman who is not a great candidate for chemotherapy and she has a large breast cancer, those women are perfectly reasonable candidates for an aromatase inhibitor prior to surgery for three to four months.
ANNOUNCER: The ATAC trial also points to another possible use of armomatase inhibitors. Some experts believe these drugs may eventually be used -- like tamoxifen -- to prevent breast cancer in women who are at especially high risk.
WILLIAM GRADISHAR, MD: The striking finding in the ATAC trial, that there was a reduction in the odds of second breast cancers, has fueled enthusiasm for at least exploring this in pilot studies in the prevention setting.
ANNOUNCER: Actual clinical use for prevention is far away, at best. Except in unusual cases.
HYMAN MUSS, MD: There might be an occasional patient with such a high risk that can't tolerate tamoxifen or has a contraindication or reason not to give tamoxifen, like a history of blood clots or other problems. But I would think to use in general practice from the data we have now would be premature.
ANNOUNCER: Tamoxifen has proven effective for over 20 years and has gained the confidence of many doctors who treat breast cancer.
Data from the ATAC trial show aromatase inhibitors may also be very effective, especially in preventing the recurrence of disease in older women.
And that means valuable, additional choices.
GENEROSA GRANA, MD: The aromatase inhibitors provide a wonderful choice of therapy for some of those women, because we now have data that for the postmenopausal woman who's hormone receptor positive there is better activity with Arimidex than with tamoxifen, and in general there's a better safety profile.
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