First Cycle Risk of Severe and Febrile Neutropenia in Cancer Patients Receiving Systemic Chemotherapy: Results from a Prospective Nationwide Study.

Introduction: Myelosuppression represents the major dose-limiting toxicity of cancer chemotherapy. This prospective, nationwide study was undertaken to better define risk of neutropenia and its complications and to develop risk models for selecting patients for appropriate supportive care.

Methods: More than 3,500 patients initiating a new chemotherapy regimen have been prospectively registered at 137 randomly selected practice sites. Major disease sites include breast, lung, colorectal, ovary and lymphoma. Primary outcomes include severe neutropenia (SN; absolute neutrophil count nadir <500) and febrile neutropenia (FN) (fever/infection and nadir <1000) by cycle of treatment and overall.

Results: This analysis is based on the first 2,361 patients treated to date including 924 (39%) age ≥65. Severe neutropenia was documented in 28% and FN in 16% across all cancer categories. The proportion of patients with ANC <500 over the first four cycles of treatment include: colorectal (8%); lung (18%); ovary (23%); lymphoma (27%) and breast (37%). Likewise, the proportion of patients with FN during the first four cycles include: colorectal (7%); lung (11%); ovary (13%); lymphoma (18%) and breast (20%). As shown in the table, approximately half of the initial episodes of ANC <500 and FN over four cycles of treatment occurred in cycle 1.

The proportion of initial episodes of severe neutropenia that occur in cycle 1 include: colorectal (67%); lung (59%); ovary (44%); lymphoma (62%) and breast (70%). Likewise, the proportion of initial episodes of FN occurring in cycle 1 include: colorectal (53%); lung (60%); ovary (57%); lymphoma (56%) and breast (58%).

Conclusions: Rates of severe and febrile neutropenia vary with tumor type. The initial episode of severe or febrile neutropenia is most likely to occur during the first cycle of chemotherapy across all major cancer types.