Newer Chemotherapies Improve Breast Cancer Outlook

Summary: Newer chemotherapy regimens have improved the outlook for breast cancer patients, according to a report in the Journal of the American Medical Association. The results were best in women whose cancers lacked hormone receptors and therefore could not be helped by hormonal treatments such as tamoxifen. The finding is based on a review of 3 successive national studies of post-operative chemotherapy in women with advanced early stage breast cancer -- cancer that has spread to nearby lymph nodes, but no further.
Why it's important: Although early breast cancers are often treated successfully, the disease can be fatal if the cancer comes back after surgery. In 2006, the American Cancer Society estimates that 41,000 women will die of this disease (more than 200,000 women will develop it). Beginning in the 1970s, doctors found that new drugs and new ways of giving these drugs could help prevent recurrence and death. Even more effective treatments have been introduced in recent years, as this study shows. Thanks to these advances, today's women have a better chance of surviving this disease than did women in the past -- even if their tumors are the more difficult type to treat, which don't respond to hormone therapies like tamoxifen or aromatase inhibitors.
"This tells us that breast oncology has made enormous strides in treating patients with [hormone-negative] tumors," said lead study author Donald Berry, PhD, chair of the Department of Biostatistics and Applied Mathematics at The University of Texas M.D. Anderson Cancer Center.
What's already known: Women whose breast cancer has spread to their lymph nodes are at risk of having the cancer come back -- most commonly in their bones, liver, and lungs. When this happens, the cancer may eventually be fatal. More than 30 years ago, doctors found that giving chemotherapy or hormone therapy to these women after their breast cancer surgery would prevent a recurrence in some of them. After years of study, it became clear that women whose cancers contained hormone receptors (about two-thirds of breast cancers have them) were especially helped by the hormone-like drug tamoxifen, even though these women often received chemotherapy also. But women whose cancers did not have hormone receptors did not respond to tamoxifen and needed chemotherapy, which became their main treatment.
How this study was done: The researchers examined the results of three large clinical trials that were carried out from 1985-1991, 1994-1997, and 1997-1999. The trials tested different chemotherapy regimens in women who had surgery for breast cancer that had spread to underarm lymph nodes. They included women with both hormone-positive and hormone-negative cancers. Each successive study matched a new regimen (either a new drug combination or a new way of giving the drugs) against the best regimen of the previous study.
What was found: Each new chemotherapy regimen proved better than the earlier one. The women who got the best-performing treatment in the most recent clinical trial had a lower chance of recurrence and a greater chance of survival than the women in the earliest trial. But this benefit was seen mainly in women whose cancers were hormone receptor-negative -- that is, the cancers lacked estrogen receptors (ER-negative). Women with ER-negative tumors had a nearly 17% improvement in their overall survival if they received chemotherapy, while those with ER-positive tumors had a 4% improvement.
Why the difference? The authors say it has to do with drugs like tamoxifen. The hormone treatments are so effective for women with ER-positive cancers that the chemotherapy adds only a little to their overall improvement. Chemotherapy shows a much greater effect in ER-negative women because they don't benefit from hormonal therapies.
"All in all, this is good news because it shows that the benefit of chemotherapy for ER-negative tumors is surprisingly dramatic in the same way that tamoxifen's effect is substantial for ER-positive tumors," Berry said.
The bottom line: Clinical trials of new chemotherapy regimens for women who have had surgery for breast cancer are helping doctors fine-tune the way they treat these patients and helping more women survive the disease. This is especially true for women with harder-to-treat ER-negative tumors.
That doesn't mean ER-positive women won't benefit from chemotherapy at all, cautioned the study's senior author, Eric Winer, MD. He is director of the Dana-Farber Breast Oncology Center and associate professor of medicine at Harvard Medical School. But it does mean there's more fine-tuning to be done.
"Women with ER-negative and ER-positive cancer should be approached differently when it comes to making a decision about [post-operative] chemotherapy," Winer said in a statement. "We need to work to identify which patients with ER-positive tumors get the largest benefit from chemotherapy."
All that speaks to the need for support and encouragement of new clinical trials to improve breast cancer treatments even more and to give each woman only the most effective treatments for her particular situation.
Citation: "Estrogen-receptor status and outcomes of modern chemotherapy for patients with node-positive breast cancer." Published in the April 12, 2006, Journal of the American Medical Association (Vol. 295, No.14: 1658-1667). First author: Donald Berry PhD, M.D. Anderson Cancer Center, Houston, Texas.