Chemotherapy-Induced Neutropenia, Anemia and Thrombocytopenia among Filipino Breast Cancer Patients on Adjuvant Chemotherapy

Lou Jorel P. Tia,1 Arthur Gregory A. Lui,1 Noel S. Chua2 and Heinrik Martin Jude S. Strebel1

1Section of Medical Oncology, Department of Medicine, College of Medicine and
Philippine General Hospital, University of the Philippines Manila
2Section of Medical Oncology, Department of Medicine,
Department of Health-Jose R. Reyes Memorial Medical Center, Manila

Introduction. Cytotoxic chemotherapy places all cancer patients at risk of developing myelosuppression. Different chemotherapy regiments could lead to development of neutropenia, anemia and thrombocytopenia which may lead to delays in facilitating chemotherapy and also maybe life threatening. This study determined the incidence of neutropenia, anemia, and thrombocytopenia per cycle of chemotherapy starting after 1st cycle among non-metastatic breast cancer patients. It also evaluated if age, size of primary tumor, number of positive lymph nodes, IHC result, BMI, co-morbidities and chemotherapy used were associated with the development of neutropenia, anemia and thrombocytopenia during the 1st cycle of chemotherapy; this may help in ascertaining which patients may need more intensive monitoring during subsequent chemotherapy sessions.

Methods. This is a time series study wherein the CBC results starting prior 1st chemotherapy cycle were gathered from medical charts of non-metastatic breast cancer patients receiving cyclophosphamide/ doxorubicin/ docetaxel/ fluororuracil chemotherapy at UP-PGH and JRRMMC Medical Oncology Clinics enrolled under the DOH-NCPAM BCMAP program, from 1 January 2009 to 31 June 2014. Incidence rates of neutropenia, anemia and thrombocytopenia were recorded per cycle of chemotherapy. Severity of myelosuppression was graded based on the Common Toxicity Criteria of the National Cancer Institute Version 2.0. Possible predictors of myelosuppression were assessed focusing on the 1st cycle of chemotherapy where assessed focusing on the 1st cycle of chemotherapy where interventions were not yet done. Standard statistical methods were used for the descriptive analysis. Variables were analyzed using the Chi square test and logistic regression; level of significance was at p<0.05.

Results. 751 patients were included in the study, who had a total of 3,759 CBC results. The incidence of neutropenia, anemia, thrombocytopenia for all 3,759 CBC results were 3%, 2.3% and 0.5%, respectively. Among all recorded CBC results only 0.9% had grade 3-4 neutropenia and 0.3% grade 3-4 anemia. There was no severe thrombocytopenia.

After the 1st chemotherapy cycle, the incidence of neutropenia was 4.67% (35 patients), anemia 2.27% (17 patients), and thrombocytopenia 0.8% (6 patients). Of these patients, only 1.17% (9 patients) experienced severe neutropenia and 0.27% (2 patients) experienced grade 3-4 anemia. No patient experienced grade 3-4 thrombocytopenia.

Age, size of primary tumor, number of positive lymph nodes, IHC result, BMI, co-morbidities and chemotherapy used were not associated with risk for myelosupression during the 1st cycle of chemotherapy.

Conclusion. Incidence rates of neutropenia, anemia and thrombocytopenia were minimal in non-metastatic breast cancer patients undergoing cytotoxic chemotheraphy, with low rates of severe myelosupression. Myelosupression from standard doxorubicin/ cyclophosphamide/ docetaxel/ flurouracil containing chemotherapy regimes can be given to non-metastatic breast cancer patients, completing required number of chemotherapy cycles with nil interruption or delay.

Key Words: myelosuppression, cytotoxic chemotherapy, breast cancer