WEDNESDAY, Oct. 10, 2007 (HealthDay News) -- When added to a standard chemotherapy, the drug paclitaxel (Taxol) cuts the recurrence of breast cancer by 41 percent in women with a particular form of tumor, a new study finds.
Those tumors are called "HER2-positive" because their cells produce an excess of the protein human epidermal growth factor receptor-2 (HER2).
In recent years, cancer specialists have found that breast tumors with different characteristics respond differently to various regimens. The new study adds another piece to that puzzle, experts say.
"Over the last 10 years, we have come to realize that breast cancer isn't one disease but a family of diseases," explained study co-author Dr. Eric Winer, director of the breast oncology center at the Dana-Farber Cancer Institute in Boston. "In this study, what we saw is very different benefits for paclitaxel in different subgroups of women," he said.
"This adds to a growing body of literature" about which chemotherapy regimens benefit which types of tumors, added the study's lead author, Dr. Daniel F. Hayes, clinical director of the breast oncology program at the University of Michigan Comprehensive Cancer Center and professor of internal medicine at the University of Michigan, Ann Arbor.
"We can use the biology of the cancer to select the [appropriate] chemotherapy," he said.
The findings are published in the Oct. 11 issue of the New England Journal of Medicine
The researchers randomly selected 1,500 women from 3,121 patients with lymph node-positive breast cancer, meaning it had spread to nearby lymph nodes; all were part of the Cancer and Leukemia Group B study, a national clinical research effort sponsored by the U.S. National Cancer Institute.
The women had been randomly assigned to get the standard anti-cancer drugs doxorubicin plus cyclophosphamide, followed by either four cycles of the drug paclitaxel or observation only.
The researchers than analyzed tissue samples supplied by the women, looking for the expression of HER2 as well as the tumor's estrogen receptor status.
"Most guidelines say, if a tumor is node-positive, chemo is recommended," Hayes said.
In this study, they found that paclitaxel helped those women whose tumors are HER2-positive, regardless of whether they were estrogen-receptor positive or negative. In contrast, patients whose cancers were HER2-negative and estrogen-receptor positive did not benefit in this study from paclitaxel.
Over the follow up of about 10 years, adding paclitaxel for the treatment of HER2-positive tumors reduced the risk of recurrence by 41 percent.
About 60 percent of women with breast cancer will have HER2-negative and estrogen-receptor positive tumors, noted Winer, who is chief scientific adviser for Susan G. Komen for the Cure, a nonprofit advocacy group.
Hayes did offer one strong caveat: "We want to be cautious about this data," he said, adding that the findings need to be confirmed in other studies.
Winer cautioned that the study, "doesn't tell us what we should do when we approach the patient in clinic tomorrow. We don't want people to say no to chemo based on these results only."
In an editorial accompanying the study, Dr. Anne Moore from Weill Cornell Medical College, New York City, concluded that "the days of 'one size fits all' therapy for patients with breast cancer are coming to an end.''
For more on breast cancer treatment, head to the American Cancer Society.