The use of white blood cell growth stimulating factor drugs to reduce risk of neutropenia-related complications in women with breast cancer receiving common first-cycle chemotherapies had only a low-to-modest benefit for most patients, according to a study published in the Journal of Clinical Oncology.
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The American Society of Clinical Oncology has recommended that oncologists not use white cell stimulating factor for prevention of neutropenia for patients with less than a 20% risk of getting an infection. In a study led by Abiy Agiro, PhD, research manager for HealthCore, researchers conducted a study to evaluate outcomes after granulocyte colony-stimulating factor (G-CSF) prophylaxis in patients with breast cancer who received chemotherapy regimens with low-to-intermediate risk of induction of neutropenia-related hospitalization.
For the study, researchers identified a total of 8745 patients aged 18 years or older using a medical and pharmacy claims database for 14 commercial US health plans. Primary prophylaxis was defined as G-CSF administration within 5 days of beginning chemotherapy. Primary outcomes included neutropenia, fever, and infection-related hospitalization within 21 days of initiating chemotherapy.
A total of 4815 patients in the study received docetaxel and cyclophosphamide; 2292 patients received docetaxel, carboplatin, and trastuzumab; and 1638 received doxorubicin and cyclophosphamide. Primary prophylaxis was used in 2849 patients, 1444 patients, and 857 patients for each respective cohort.
More patients treated with doxorubicin, cyclophosphamide and G-CSF experienced neutropenia than those who did not receive G-CSF, although the difference was not significant. However, in the other two groups, patients who received a primary prophylaxis were less likely to experience neutropenia-related complications than those who did not. For those who received docetaxel and cyclophosphamide, 20 patients would have to be treated for 21 days to avoid one neutropenia-related hospitalization; with the docetaxel, carboplatin, and trastuzumab regimen, 18 patients would have to be treated.
Thus, researchers concluded that G-CSF prophylaxis had limited benefit in lowering neutropenia-related hospitalization in patients with breast cancer who received docetaxel and cyclophosphamide or docetaxel, carboplatin, and trastuzumab. More data are needed to determine which patients with breast cancer are most likely to benefit from G-CSF.
“In women with breast cancer treated with a conventional dose of doxorubicin and cyclophosphamide, a chemotherapy regimen that has low risk of infection, more than half of them were also treated with G-CSF, with no benefit,” said Dr Agiro. “This is unfortunate, especially given that patients can experience uncomfortable side effects from G-CSF, such as bone pain, headache and nausea. When the chemotherapy risk for neutropenia is low, these high-cost agents place an unnecessary burden on the healthcare system without providing a discernable benefit to the patient.”
