'Powerful Trend': Chemo Use for Breast Cancer Drops

Between 2013 and 2015, the use of chemotherapy for early-stage breast cancer in the United States significantly decreased, according to a new survey of women from two Surveillance, Epidemiology, and End Results (SEER) registries.

The decline has occurred without a substantial change in practice guidelines, the authors note, but coincides with increasing use of genomic profiling tests, which identify patient with a low risk for recurrence who can skip chemotherapy.

Overall, during the 3-year study period, estimated chemotherapy use declined from 34.5% to 21.3% among the 2926 study participants (P < .001).

The women all had stage I or II, estrogen receptor–positive, human epidermal growth factor receptor 2–negative breast cancer.

The patients were also analyzed by nodal status. For node-negative patients, who also included those with micrometastases, the estimated decline in chemotherapy use was from 26.6% to 14.1%. For node-positive patients, the decline was greater: from 81.1% to 64.2%.

The new study was published online December 11 in the Journal of the National Cancer Institute.

The authors, led by Allison Kurian, MD, associate professor of medicine and of health research and policy at Stanford University in California, point out that four other studies in preceding years have also found a declining use of adjuvant chemotherapy in this setting, which has been coincidental with increasing use of genomic profiling in the United States. These genomic profiling tests provide insight into the likely benefit of the invariably toxic therapy and identify women who can skip chemotherapy.

Overall, the authors see a "broad change in culture" and a "powerful trend" as "oncologists [are] moving away from chemotherapy for patients with hormone-responsive early breast cancer."

Asked for comment, Mateusz Opyrchal, MD, PhD, assistant professor of oncology at the Roswell Park Cancer Institute in Buffalo, New York, said that the trends in declining chemotherapy use seen in the new analysis are here to stay.

"As our knowledge base and comfort with tests designed to predict benefit from chemotherapy increases, this trend should continue and patients will benefit from not receiving unnecessary therapy," he told Medscape Medical News.

'We have had increasing confidence in determining specific tumor subtypes that do not seem to receive benefit from chemotherapy," he added.

Details of New Study

The new study is "unique" in many ways, Dr Kurian told Medscape Medical News: "We quantified the extent to which tumor genomic profiling contributed to the observed trends, and we characterized how oncologists make decisions about whether to treat patients with chemotherapy."

In the study, Dr Kurian and colleagues surveyed 5080 women treated for early-stage breast cancer between 2013 and 2015 who were part of the SEER registries in Georgia and Los Angeles, which are socioeconomically and ethnically diverse areas. They had a 70% response rate; 2926 study participants answered questions on their receipt of chemotherapy and their oncologists' recommendations.

The researchers could quantify the genomic profiling effect on chemo use because Genomic Health, the manufacturer of the Oncotype DX 21-gene recurrence score (RS), provided data on RS testing on the patients. The RS test status and results for the patients were merged with their related SEER data.

During the study period, use of the RS did not change among the node-negative patients but increased in node-positive patients. Notably, that use "accounted for one-third of the chemotherapy decline." In other words, the RS results encouraged decisions whereby patients and their physicians opted out of what was once standard treatment for node-positive early breast cancer.

As part of the survey, the patients with breast cancer also reported a decline in chemotherapy recommendations by their oncologists, from 44.9% to 31.6%.

The new study also included a survey of 504 attending oncologists (60% response rate) about their chemotherapy recommendations, for both node-positive and node-negative early-stage disease.

A total of 67.4% of oncologists were "much more likely" to order genomic profiling with RS if patient preferences were discordant with the doctor's recommendation than if they were concordant (67.4% vs 17.5%).

"We believe this study indicates that physicians are attempting to be more selective in their recommendations and to spare patients toxicity when possible," said Dr Kurian in a press statement. "As personalized medicine becomes more widely available, doctors are using test results as part of their dialogue with patients about their preferences and overall treatment goals," she said about genomic profiling tests.

The trends in the decline of chemotherapy use are also part of a cultural change, according to the authors.

Dr Kurian put it this way: "This likely reflects a change in the culture of how physicians are practicing, and a move toward using tumor biology to guide treatment choices rather than solely relying on clinical measures."

But there is a red flag, the authors acknowledged. Long-term outcomes of these recent changes in chemotherapy use are "uncertain."

To that end, two major clinical trials, TAILORx and RxPONDER, will provide "relevant evidence," Dr Kurian said.

TAILORx is a randomized phase 3 trial evaluating hormone therapy alone or hormone therapy plus chemotherapy in women with node-negative, estrogen receptor–positive breast cancer in conjunction with an Oncotype DX test or RS, and assigning treatment based an RS of 11 to 25.

RxPONDER is a randomized phase 3 trial for node-positive, estrogen receptor–positive breast cancer evaluating the use of the RS in deciding whether to administer chemotherapy to patients with node-positive disease who are receiving endocrine therapy.

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References
SOURCE:

'Powerful Trend': Chemo Use for Breast Cancer Drops - Medscape - Dec 18, 2017.

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