FIRST-CYCLE BLOOD COUNTS AND SUBSEQUENT NEUTROPENIA, DOSE REDUCTION, OR DELAY IN EARLY-STAGE BREAST-CANCER THERAPY

Purpose: If patients could be ranked according to their projected need for supportive care therapy, then more efficient and less costly trea tment algorithms might be developed. This work reports on the construc tion of a model of neutropenia, dose reduction, or delay that rank-ord ers patients according to their need for costly supportive care such a s granulocyte growth factors. Patients and Methods: A case series and consecutive sample of patients treated for breast cancer were studied. Patients had received standard-dose adjuvant chemotherapy for early-s tage nonmetastatic breast cancer and were treated by four medical onco logists. Using 95 patients and validated with 80 additional patients, development models were constructed to predict one or more of the foll owing events: neutropenia (absolute neutrophil count [ANC] less than o r equal to 250/mu L), dose reduction greater than or equal to 15% of t hat scheduled, or treatment delay greater than or equal to 7 days. Two approaches to modeling were attempted. The pretreatment approach used only pretreatment predictors such as chemotherapy regimen and radiati on history; the conditional approach included, in addition, blood coun t information obtained in the first cycle of treatment. Results: The p retreatment model was unsuccessful at predicting neutropenia, dose red uction, or delay (c-statistic = 0.63). Conditional models were good pr edictors of subsequent events after cycle 1 (c-statistic = 0.87 and 0. 78 for development and validation samples, respectively). The depth of the first-cycle ANC was an excellent predictor of events in subsequen t cycles (P = .0001 to .004). Chemotherapy plus radiation also increas ed the risk of subsequent events (P = .0011 to .0901). Decline in hemo globin (HGB) level during the first cycle of therapy was a significant predictor of events in the development study(P = .0074 and .0015), an d although the trend was similar in the validation study, HGB decline failed to reach statistical significance, Conclusion: It is possible t o rank patients according to their need of supportive care based on bl ood counts observed in the first cycle of therapy. Such rankings may a id in the choice of appropriate supportive care for patients with earl y-stage breast cancer. (C) 1998 by American Society of Clinical Oncolo gy.