Fatigue in Breast Cancer Patients Studied
Researchers have defined aspects of disabling fatigue that persists for years in almost one-third of breast cancer survivors, says a report in the medical journal Clinical Cancer Research.
The key to breast cancer patients’ fatigue stems from responses within their immune systems, say the researchers.
"These studies identify a biological basis for persistent fatigue in cancer survivors that is implemented by inflammation," says Dr. Michael Irwin, an expert at the UCLA Jonsson Cancer Center.
"We have detected a biological marker that is a composite of two immune response elements," he adds. "This biomarker identifies - and can predict - which women have long term persistent fatigue.
"These findings point the way for development of novel treatment strategies that decrease this inflammatory response and thwart the fatigue that these patients endure," explains Dr. Irwin.
Battling breast cancer is a daunting challenge to women diagnosed with the disease, but with advanced screening and treatment strategies, patients with early stage breast cancer are surviving longer.
Breast cancer survivors are the largest group of patients to overcome any type of cancer in the US.
While patients surviving other types of cancer also can experience the long-lasting fatigue syndrome, a greater proportion of breast cancer survivors endure the condition.
Cancer researchers had explored various possible reasons for the persistent fatigue in breast cancer survivors, Dr. Irwin says, such as different kinds of treatment, or biological events including anemia.
One component of the marker the scientists studied is a measure of the amount of interleukin-6 receptor (IL-6R) in the blood of breast cancer survivors.
He compares this free-floating receptor to the amount of that receptor remaining on the membranes of specific blood cells, where the receptor normally is found and functions within the immune response.
This receptor is usually embedded on the surface membrane of white blood cells, or monocytes.
In some survivors, however, many of the IL-6R are shed from the monocytes and are then found within the blood plasma.
Those free-floating receptors can still bind to circulating cytokine IL-6, Dr. Irwin notes. In that form they have the potential to interact with cells that normally do not respond to cytokine/receptor activation, such as brain cells that may regulate fatigue sensation.
IL6 is a biological chemical that helps drive initial immune responses within people.
"IL-6 contributes to an activation of monocytes in the blood, and enables antigen presenting cells to activate T cells as part of the cellular immune response," Dr. Irwin says.
The second component of the marker is characterized by CD69, a cell membrane protein that indicates early activation of those T cells.
Patients with a decreased number of CD69+ T cells along with other factors were likely to experience persistent fatigue.
Dr. Irwin's research is the first to document a link between biological mechanisms involved with the immune response and persistent fatigue.
"It is such an important quality of life issue," he says. "Many patients are surviving from their cancer treatments, but they are surviving with substantial impairments in their ability to carry on their lives.
"We've addressed the cancer in these survivors, and now we can also address the functional declines in the quality of life of these patients."
Always consult your physician for more information.
|
