Study Identifies Risk of Chemotherapy-Related Hospitalization for Early-Stage Breast Cancer Patients
Oncologists now have a new understanding of the toxicity levels of specific chemotherapy regimens used for women with early-stage breast cancer, according to research from The University of Texas MD Anderson Cancer Center. The retrospective study, reported in the Journal of Clinical Oncology by Barcenas et al, used large population-based data to compare the risk of hospitalization for six common chemotherapy regimens. Reasons for hospitalization included infection, fever, anemia, dehydration, neutropenia, thrombocytopenia, and delirium.
“The novelty of our study is that we were able to identify and delineate between different chemotherapy regimens in early-stage breast cancer using claims data, considered as real-world and non–clinical trial information,” said study author Carlos Barcenas, MD, Assistant Professor, Breast Medical Oncology, at MD Anderson.
There have been several prior publications in the health services research field addressing chemotherapy toxicity using claims data, but they don’t outline specific chemotherapy regimens, Dr. Barcenas explained.
“The difficulty in the methodology is that most of these regimens are composed of several agents and have specific cycling times. The chemotherapy regimens have usually been referred to as ‘anthracycline’ or ‘taxane-based,’” he said. “By characterizing subsets of patients at greatest risk for developing toxicities and adverse side-effects, clinicians may be able to select more tolerable treatments.”
Study Details
Researchers combined data from the Surveillance, Epidemiology and End Results (SEER) registry, compiled by the National Cancer Institute, and the Texas Cancer Registry to identify 3,567 patients ages 65 and older being treated for early-stage breast cancer between 2003 and 2007. Additional data from Marketscan, a nationwide employment claims database, identified 9,327 patients younger than 65 years of age with early-stage disease.
Patients were then categorized into groups according to the chemotherapy regimens they received including:
- Docetaxel/cyclophosphamide cycled every 3 weeks
- Doxorubicin/cyclophosphamide cycled every 3 weeks
- Docetaxel/doxorubicin/cyclophosphamide cycled every 3 weeks
- Doxorubicin/cyclophosphamide cycled every 3 weeks, followed or preceded by docetaxel cycled every 3 weeks
- Dose-dense doxorubicin/cyclophosphamide cycled every 2 weeks, followed or preceded by paclitaxel cycled every 2 weeks
- Doxorubicin/cyclophosphamide cycled every 3 weeks followed or preceded by weekly paclitaxel
Among patients younger than 65 years of age, the hospitalization rates ranged from 6.2% (dose-dense doxorubicin/cyclophosphamide plus paclitaxel) to 10% (docetaxel/doxorubicin/cyclophosphamide). In patients older than 65, rates ranged from 12.7% (docetaxel/cyclophosphamide) to 24.2% (docetaxel/doxorubicin/cyclophosphamide).
“Our findings demonstrate that [docetaxel/doxorubicin/cyclophosphamide] and [doxorubicin/cyclophosphamide plus docetaxel] were associated with the highest risk of hospitalization in patients younger than age 65,” Dr. Barcenas said. “And for older patients all regimens, aside from [dose-dense doxorubicin/cyclophosphamide plus paclitaxel], were associated with a higher risk of hospitalization compared to the [docetaxel/cyclophosphamide] regimen.”
Study Limitations
Dr. Barcenas noted these findings need to be taken with the consideration of potential biases where less aggressive regimens may have been offered to patients who are frailer.
Additionally, Dr. Barcenas said that findings showed that the use of the docetaxel and cyclophosphamide regimen has significantly increased over time, without any current evidence from clinical trials that this regimen is noninferior to anthracycline and taxane-based chemotherapy regimens.
The authors noted several limitations exist with retrospective claims data research, including the inability to adjust for other clinical factors such as comorbidities and therapy responses. Also, hospitalization data often underrepresents chemotherapy toxicities as mild events are usually managed in the outpatient setting.
Additional research is necessary to validate the study methodology. The most important question is which of these treatments is most effective for patients. It is likely that many of these regimens are similar in effectiveness and this study will help guide treatment by allowing physicians to pick the least toxic therapies, Dr. Barcenas said.
Sharon H. Giordano, MD, MPH, of The University of Texas MD Anderson Cancer Center, is the corresponding author for the Journal of Clinical Oncology article.
This work was supported in part by the Center for Comparative Effectiveness Research on Cancer in Texas, the National Institutes of Health, the Dickson Fund for Breast Cancer Research, and the Duncan Family Institute. Linda S. Elting, PhD, reported research funding from Helsinn. Benjamin D. Smith, MD, reported research funding from Varian Medical Systems.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
