Herceptin (chemical name: trastuzumab) is a targeted therapy medicine approved to treat advanced-stage HER2-positive breast cancers and to lower the risk of the cancer coming back (recurrence) in women with HER2-positive, early-stage breast cancer that has a high risk of recurrence.
The study reviewed here found that Herceptin also offers benefits to women diagnosed with HER2-positive, early-stage breast cancer with a low risk of recurrence. The results were presented at the 2009 ASCO Breast Cancer Symposium.
When deciding if HER2-positive, early-stage breast cancer has a high risk of recurrence, doctors look for specific cancer characteristics, including:
Still, doctors often use Herceptin to treat many HER2-positive, early-stage breast cancers without all of these characteristics -- meaning they have a lower risk of recurrence. For example, HER2-positive breast cancers that are smaller than 2 cm are considered to have a lower risk of recurrence.
In this study, the researchers wanted to see if using Herceptin to treat HER2-positive, early-stage breast cancers with a low risk of recurrence makes sense. They looked at two groups of women:
The researchers wanted to see if there were differences in outcomes between the women who got Herceptin and the women who didn't get Herceptin at 2 and 4 years after diagnosis.
Two years after diagnosis, survival was essentially the same, but Herceptin did show some small benefits:
Four years after diagnosis, Herceptin showed more substantial benefits:
The researchers pointed out that some of the recurrence reduction benefits that seemed to come from Herceptin may have been because chemotherapy was used more consistently during treatment. About 33% of the women that didn't get Herceptin also didn't get chemotherapy. Chemotherapy, like Herceptin, can reduce the risk of recurrence of both HER2-positive and HER2-negative breast cancers.
While these results are promising, more research needs to be done before researchers can be sure that using Herceptin to treat HER2-positive breast cancers with a low risk of recurrence makes sense. If you've been diagnosed with HER2-positive, early-stage breast cancer, you'll want to do all that you can to keep your risk of recurrence as low as possible. This may include chemotherapy and Herceptin treatments. Talk to your doctor about the cancer's characteristics and your risk of recurrence. You may want to discuss this study and ask if Herceptin treatment makes sense for your specific situation.
Breastcancer.org's pages on Herceptin offer much more information about this targeted therapy medicine.
SAN FRANCISCO (MedPage Today) -- Trastuzumab (Herceptin) appears to improve outcomes even for women at low risk of recurrence due to small, node-negative, HER2-positive breast cancer, researchers found in a retrospective study.
Although the targeted therapy had been studied and approved only for high-risk HER2 overexpressing breast cancers in conjunction with chemotherapy, the same combination appeared to substantially reduce local and distant recurrences and mortality rates in the low risk setting, Heather L. McArthur, MD, MPH, of Memorial Sloan-Kettering Cancer Center in New York City, reported here at the ASCO Breast Cancer Symposium.
The low rate of all events in the retrospective single-center study was encouraging, but made it difficult to compare with the effect size seen in the randomized trials in node-positive and high-risk, node-negative tumors, McArthur said.
Nevertheless, the consistency of benefit across outcome measures in the low-risk cancers suggested that the effect was real, she said.
One of the "high risk" features used as a threshold for treating with trastuzumab is a tumor size greater than 2 cm. But because this cutoff felt arbitrary when faced with 1.9-cm diameter breast cancers, McArthur said, the drug gained wide use in smaller and otherwise low-risk patients treated at her institution.
Thus in the real world setting the majority of women with 2-cm or smaller, node-negative, HER2-positive early stage invasive breast cancer received the trastuzumab-chemotherapy regimen approved for high-risk patients.
McArthur's group went back and looked at how effective this treatment was compared with a historical group treated in the pre-trastuzumab era to minimize selection bias.
The 108 women who met the above low-risk criteria in the pre-trastuzumab period from 2002 through mid-May 2004 had nearly identical tumor, surgical, and treatment characteristics as the 149 treated with trastuzumab through the end of 2008. The only difference was that one-third of the pre-trastuzumab group did not get any chemotherapy.
Outcomes at two-years of follow-up -- the median for the trastuzumab group -- showed equally high overall survival rates as might be expected over the short-term (99% with and 100% without trastuzumab). But locoregional and contralateral recurrence-free survival was better with the targeted therapy (99% versus 91%) as was the more critical, distant recurrence-free survival (100% versus 98%).
By four years' follow-up -- the maximum available for the trastuzumab group -- the comparison favored trastuzumab even more:
The researchers cautioned that the entire benefit could not be attributed to trastuzumab, because its use was confounded by use of chemotherapy and at higher rates than in the pre-trastuzumab era.
Lori Pierce, MD, of the University of Michigan in Ann Arbor and a co-chair of the conference program committee, called the findings provocative.
But she noted, "It will be important to test this hypothesis prospectively to be sure the potential benefit of trastuzumab is not over-estimated in this low-risk patient population."
The low event rate could limit the feasibility of a randomized trial in this setting, though, McArthur said.
The researchers reported conflicts of interest, including research funding, from Genetech BioOncology.
Pierce reported having received research funding from the National Institutes of Health and the Breast Cancer Research Foundation.
Primary source: ASCO Breast Cancer Symposium Source reference: McArthur HL, et al "Benefits of trastuzumab-based therapy for women with small, node-negative, HER2-positive breast cancer" ASCO Breast 2009; Abstract 228.
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