Researchers from the University of Texas MD Anderson Cancer Center compared different chemotherapy regimens to measure the risk of hospitalization between patients with early-stage breast cancer, revealing a new understanding of the toxicity levels of specific chemotherapy regimens.
The study, led by assistant professor Carlos Barcenas and published in the Journal of Clinical Oncology, identified 3,567 patients 65 years and older from the SEER/Texas Cancer Registry-Medicare database and 9,327 patients younger than 65 from the MarketScan database, all of whom were diagnosed with early-stage breast cancer between 2003 and 2007.
Researchers categorized patients according to the regimens they received: docetaxel (T) and cyclophosphamide ©, doxorubicin (A) and C, TAC, AC + T, dose-dense AC + paclitaxel (P) or AC + weekly P. From there, researchers compared the rates of chemotherapy-related hospitalizations that occurred within 6 months of chemotherapy initiation, identifying the factors associated with these hospitalizations.
Reasons for hospitalization included infection, fever, anemia, dehydration, neutropenia (low white blood cell count), thrombocytopenia (low blood platelets), and delirium.
As a result, the team found that TAC and AC + T were associated with the highest risk of hospitalization in patients younger than 65 years old. Conversely, among patients older than 65 years old, all regimens (aside from dose-dense AC + P) were associated with a higher risk of hospitalization than TC.
According to Dr. Barcenas, this was the first time researchers were able to identify and delineate between different chemotherapy regimens in early-stage breast cancer through the use of claims data, which can be considered as “real-world and non-clinical trial information,” because, although there have been several prior publications addressing chemotherapy toxicity using claims data, they don’t outline specific chemotherapy regimens.
Most of chemotherapy regimens, Barcenas explains, are composed of several agents and have specific cycling times. “By characterizing subsets of patients at greatest risk for developing toxicities and adverse side-effects, clinicians may be able to select more tolerable treatments,” he said.
To find which of these treatments is most effective for patients, additional research is necessary to validate the study methodology, Barcenas added.
This work was supported in part by the Center for Comparative Effectiveness Research on Cancer in Texas, a multi-university consortium funded by the Cancer Prevention and Research Institute of Texas, the National Institutes of Health through MD Anderson’s Cancer Center Support Grant, the Dickson Fund for Breast Cancer Research and the Duncan Family Institute.
Other authors on the all MD Anderson study include Sharon Giordano, M.D., Jiangong Niu, Ning Zhang, Yufeng Zhang, Linda Elting, Ph.D., of Health Services Research; Gabriel Hortobagyi, M.D., Breast Medical Oncology; and Thomas Buchholz, M.D. and Benjamin Smith, M.D., of Radiation Oncology.