Granulocyte Colony-Stimulating Factor (G-CSF) Prevents Common Chemotherapy Complication
Neutropenia, granulocyte colony-stimulating factor (G-CSF), filgrastim (Neupogen®), pegfilgrastim (Neulasta®), lenograstim (Granocyte®). (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary.)
Fever plus a drop in the number of infection-fighting white blood cells is a potentially fatal complication of chemotherapy. A combined analysis of 17 clinical trials confirmed that cancer patients receiving chemotherapy are less likely to suffer this complication – called febrile neutropenia – when they also receive drugs that stimulate white blood cell production. It remains unclear, however, whether the additional treatment helps patients to remain cancer free or live longer.
Journal of Clinical Oncology, July 20, 2007 (see the journal abstract).
(J Clin Oncol. 2007 Jul 20;25(21):3158-67)
In addition to killing cancer cells, chemotherapy drugs often damage the bone marrow’s ability to produce white blood cells. A drop in white blood cells, known as neutropenia, increases the patient’s risk of contracting an infection. Fever combined with a low white blood cell count, or febrile neutropenia, can be a life-threatening complication of chemotherapy.
Granulocyte colony-stimulating factor (G-CSF) is a hormone produced by the body that stimulates the bone marrow to produce more white blood cells. G-CSF is also made as a drug. Studies have found that G-CSF injections reduce the severity and duration of neutropenia in patients with some types of cancer. It’s been unclear, however, whether G-CSF is helpful only in certain circumstances or whether many patients with cancer might benefit from it.
Treatment with a G-CSF drug is a form of biological therapy. Three forms of G-CSF are commercially available: filgrastim (Neupogen®), pegfilgrastim (Neulasta®), and lenograstim (Granocyte®).
To get a better handle on the potential benefits of G-CSF, researchers conducted a meta-analysis, a type of study in which data from numerous other studies are combined and summarized. This technique may be used to try to answer a research question when individual studies have failed to produce a definitive answer.
Researchers combined data from 17 clinical trials involving 3,493 adult cancer patients who were being treated with chemotherapy. In all the trials, patients had been assigned at random to receive injections of G-CSF, injections of a placebo, or no additional treatment.
The principal investigator for the meta-analysis was Nicole M. Kuderer, M.D., of the University of Rochester Medical Center in Rochester, New York.
Febrile neutropenia occurred one or more times in 22.4 percent of patients treated with G-CSF, compared with 39.5 percent of patients who received a placebo or no additional treatment (the control group). G-CSF reduced the risk of febrile neutropenia regardless of the type of cancer patients had or the type of G-CSF they received.
Fewer patients treated with G-CSF died while receiving chemotherapy (3.5 percent versus 5.7 percent of those in the control group). Additionally, fewer patients receiving G-CSF died of infection (1.5 per cent versus 2.8 percent in the control group).
More patients treated with G-CSF reported suffering from bone or muscle pain during the course of chemotherapy (19.6 percent versus 10.4 percent of those in the control group).
G-CSF helped patients tolerate their chemotherapy. On average, patients treated with G-CSF received more than 90 percent of the total amount of chemotherapy planned. Many patients in the control group, by contrast, received less than 90 percent of the total amount of chemotherapy planned.
The meta-analysis could not determine with statistical significance whether patients treated with G-CSF lived longer or remained cancer-free for longer than those in the control group.
The findings of this meta-analysis are in line with guidelines published by the American Society of Clinical Oncology (ASCO) in 2006, which recommend the use of G-CSF when a patient’s risk of febrile neutropenia is deemed to be greater than 20 percent, says Richard F. Little, M.D., of the National Cancer Institute’s Cancer Therapy Evaluation Program.
“If the risk of febrile neutropenia is low (less than 20 percent), routine use of G-CSF will in many cases only increase adverse effects without adding benefit,” he adds. “This study reinforces the current ASCO guidelines.”
The fact that G-CSF helps patients to stay on chemotherapy as planned may be important, says Little. For some types of cancer, he explains, studies suggest that chemotherapy is more likely to cure the disease if the patient receives a higher percentage of the planned dose.