Change in cycle 1 to cycle 2 haematological counts predicts toxicity in older patients with breast cancer receiving adjuvant chemotherapy

To determine the association between changes in complete blood counts and grade 3 or 4 toxicities from cycle 1 to cycle 2 during adjuvant chemotherapy in women > or =65 years of age with breast cancer. A retrospective review was performed on 1405 patients > or =65 years of age who were treated for primary invasive breast cancer at Memorial Sloan-Kettering Cancer Center between January 1998 and December 2000. From this cohort, we identified patients with stage I-III breast cancer who received adjuvant chemotherapy: cyclophosphamide, methotrexate and fluorouracil (CMF) or the anthracycline-based regimens doxorubicin and cyclophosphamide (AC) or AC followed by paclitaxel (AC-T). Patients were excluded from the analysis if they had a prior history of breast cancer or chemotherapy, or if they had no baseline blood counts available for review. Toxicities, dose modification and causality were recorded. The 104 patients who met our criteria had received either CMF (n = 58; mean age 70.6 years, range 65-78) or an anthracycline-based regimen (n = 46; mean age 68.9 years, range 65-77). Of these patients, 50% experienced treatment delay or treatment-related grade 3 or 4 toxicity. A decrease in white blood cell count and absolute neutrophil count from cycle 1 to cycle 2 was associated with grade 3 or 4 haematological toxicity, febrile neutropenia, hospitalisation and initiation of filgrastim for secondary prophylaxis. A decrease in haemoglobin was associated with febrile neutropenia and hospitalisation. Advanced age was not associated with a significant change in complete blood counts, other than a decline in absolute neutrophil count in patients receiving CMF. In this cohort of older patients who received chemotherapy for breast cancer, changes in blood counts from cycle 1 to cycle 2 were associated with increased risk of treatment-related grade 3 or 4 toxicity.