Nadir platelet counts in patients on doxorubicin and cyclophosphamide (ac); and cyclophosphamide, doxorubicin, vincristine and prednisone (chop) for breast cancer and non-hodgkin's lymphoma respectively
Background: Patients on chemotherapy suffer severe myelosuppression leading to poorer treatment outcome locally compared to economically advantaged countries. Effective and safe use of chemotherapy demands that febrile neutropaenia and haemarrhage, which are the most important consequences of chemotherapy-induced myelosuppression in the acute stage, should be well managed; and formulation of meaningful local guidelines to achieve timely interventions requires analysis of nadir counts. A clearer. pattern .of nadir neutrophil counts has been better described locally than that of nadir platelet counts. With this in mind, we set out to study the effects of using doxorubicin and cyclophosphamide (AC) for breast cancer and cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) for non-hodgkin's lymphoma (NHL) on the platelet counts of our patients. Objectives: To determine the nadir platelet counts on day ten to fourteen of the first two cycles, and their relationship to the risk of haemarrhage in patients on standard treatment for breast cancer and non-Hodgkin's lymphoma (NHL) with doxorubicin and cyclophosphamide (AC) and cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) protocols respectively. Methods: A prospective descriptive study using a real life usual practice scenario carried out at Kenyatta National Hospital (KNH) in Nairobi, Kenya. Samples of three milliliters of venous blood were taken from study patients on day 1 of the first three cycles and between day 10 and day 14 of the first two cycles and were analysed for full blood counts. Study patients were also evaluated for episodes of bleeding and for factors known to be associated with haemarrhage in chemotherapy induced thrombocytopaenia. Results: Seventy eight patients were analysed, of whom 61 (78.2%) had breast cancer and 17 (21.8%) had NHL. The mean platelet count for the 78 patients dropped by 142.31x1091L in cycle 1 from 335.50 (SO 98.4) x1091L to a nadir of 193.19 (SO 73.7)x1091L then rose by 128.22 x1dlL to 321.41 (SO 104.6)x109IL by day 22. In cycle 2 the mean platelet count for the 78 patients dropped by 185.54x1091L to a nadir of 135.87 (SO 75.97)x 1091Lthen rose by 171.28x1091L to 307.15 (SO 113.97)x109IL by day 43. This trend represents a 42.4% drop in cycle 1 and a 57.7% drop in cycle 2. Low nadir counts were associated with old age (2:60 years) and low baseline platelet counts in both cycles as well as low baseline total lymphocyte counts in cycle 1. In terms of nadir platelet count depths, high values were associated with high baseline platelet counts in both cycles and doxorubicin and cyclophosphamide (AC) therapy for breast cancer in cycle 2. Severe thrombocytopaenia occurred only in the second cycle and only in 3 (3.8%) patients (two patients had grade 3 thrombocytopaenia and one patient had grade 4 thrombocytopaenia). Only one patient had a minor bleeding episode (grade 1) which was not attributable to platelets. Conclusion: There is a consistent but clinically insignificant drop in platelet counts in patients on doxorubicin and cyclophosphamide (AC) and cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) for breast cancer and non-Hodgkin's lymphoma (NHL) respectively; with a tendency towards an accumulative effect. Old age and low baseline platelet counts were associated with low nadir platelet counts in both cycles; and AC therapy for breast cancer was associated with deeper platelet nadir drops from baseline.