Data from a new study published in today's Journal of Clinical Oncology points to an alarming pattern in breast cancer treatment -- less than half of women with early stage breast cancer whose records were evaluated received their full, recommended dose of potentially life-saving chemotherapy.
Researchers from the University of Rochester's James P. Wilmot Cancer Center conducted a comprehensive retrospective analysis and found that 56 percent of the 20,799 women treated for early stage breast cancer in 1,243 community-based oncology practices nationwide received less than 85 percent of their prescribed chemotherapy dose intensity due to treatment delays or dose reductions.
In 25 percent of the cases, patients saw treatment delays of more than a week and 37 percent had chemotherapy dose reductions due to common side effects of treatment, says Gary H. Lyman, M.D., M.P.H., lead author of the study and director of the health services and outcomes research program at the Wilmot Cancer Center.
Previous studies have demonstrated that receiving less than 85 percent of the recommended dose intensity can result in lower survival rates for women with breast cancer.
The primary cause of chemotherapy delays and dose reductions is neutropenia, a shortage of infection-fighting white blood cells. This is a common, potentially serious side effect of chemotherapy.
Chemotherapy drugs are designed to destroy cancer cells, but unfortunately healthy cells are also killed, including the white blood cells that protect against infection. When a patient's white blood cell count drops too low, they are at increased risk of developing infections and chemotherapy often has to be delayed until these essential white blood cells are replenished.
Although white blood cell boosters, known as colony-stimulating factors, are available to manage neutropenia, researchers found that only a quarter of the patients received them during chemotherapy. Most were prescribed in reaction to neutropenia, rather than as a preventative or prophylactic measure.
"Far too many patients are not receiving the chemotherapy doses they need in order to have the best chance of remission or cure," said Lyman, director of the Awareness of Neutropenia in Chemotherapy Study Group at the Wilmot Cancer Center. "Much of the reduction in dose and overall reduced relative dose intensity compared to the reference standard was either planned or already seen during the first chemotherapy cycle. We need to find better ways to identify patients at risk in order to provide optimal supportive care."
The researchers note that these results are particularly alarming in the face of multiple, prior studies, which underscore the importance of maintaining full chemotherapy dose-intensity, especially in responsive and potentially curable malignancies like early stage breast cancer. Specific treatment regimen and schedule, age and obesity were also associated with an increased risk of treatment delays and dose reductions.
Elderly Patients at Greatest Risk
According to the study, an unusually large number of patients age 65 and older were found to be significantly less likely to receive the recommended dose of chemotherapy, even though studies have shown that elderly patients can benefit from chemotherapy as much as younger patients. In fact, about two-thirds of older patients received less than 85 percent of the recommended chemotherapy dose.
"Fortunately, today doctors have medicines which they did not have years ago to help avoid some of the serious side-effects of chemotherapy that can lead to dose delays and reductions," Lyman said.
The women included in the analysis ranged in age from 11 to 90, with an average age of 52. Seventeen percent of the patients were 65 years or older, and 51 percent of the total patient population was reported to be pre-menopausal.
Breast cancer is the most common form of cancer among women in the United States, with more than 200,000 new cases and 40,000 deaths annually.
The Awareness of Neutropenia in Chemotherapy (ANC) Study Group, based at the Wilmot Cancer Center at University of Rochester Medical Center, was formed in September 2000 to develop more accurate prediction models for neutropenia.
Directed by leading U.S. hematologists and oncologists Gary Lyman, M.D., M.PH., David Dale, M.D., and Jeffrey Crawford, M.D., the group focuses on neutropenia awareness, treatment effectiveness and long-term survival. The group also studies the cost and quality-of-life impacts of chemotherapy-induced neutropenia. The ANC Study group is supported by a grant from Amgen.
Journal
Journal of Clinical Oncology