Cutting immunity with chemotherapy cues.
After repeatedly experiencing the immune-suppressing effects of chemotherapy in the distinctive hospital environment, cancer patients may undergo immunity dips triggered merely by a return to the hospital, according to a new pilot study.
A group of 20 women receiving chemotherapy infusions for ovarian cancer displayed both decreased immune function and increased nausea several hours before subsequent hospital-based treatments, report Dana H. Bovbjerg of Memorial Sloan-Kettering Cancer Center in New York City and his colleagues in the April JOURNAL OF CONSULTING AND CLINICAL PSYCHOLOGY.
"These are intriguing but preliminary findings," Bovbjerg says. "Their clinical implications are unknown."
It remains unclear, for instance, whether the women with the sharpest plunges in immune function were at greater risk for infection.
Nevertheless, this is the first human study to support previous observations of acquired immune suppression in animals. In a process known as classical conditioning, researchers have exposed rats to both a "neutral" stimulus -- say, sweetened water -- and an "unconditioned" stimulus -- injections of chemotherapy drugs that suppress immunity. After only one such trial, the animals' immune responses were conditioned to drop with just a taste of the sweetened water, which the rats had already begun to associate with unpleasantness.
Since chemotherapy can also cause nausea, researchers have speculated that classical conditioning promotes the nausea and vomiting experienced by at least one in four chemotherapy patients at the sound of the nurse's voice, the sight of the hospital clinic, or other hospital-related cues.
Bovbjerg and his co-workers studied women who had received at least three chemotherapy infusions. Blood samples were collected at patients' homes several days before the next treatment and at the hospital just before chemotherapy administration. Lab tests revealed that the average proliferation of white blood cells in response to two substances that promote cell division was significantly lower in samples drawn at the hospital than in those taken at patients' homes. This decrease in immune response was not related to anxiety levels reported by patients, Bovbjerg notes.
Most individual immune changes, though statistically significant, were not drastic. A few patients underwent dramatic immune reductions, but these may have been isolated fluctuations largely induced by the chemotherapy, Bovbjerg adds.