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Issues in the Management of Cancer-Related Thrombocytopenia

Issues in the Management of Cancer-Related Thrombocytopenia

Drs. Goodnough and DiPersio
present an authoritative and
informative discussion of the management of thrombocytopenia in the cancer
patient, emphasizing the risks of platelet transfusions, the safety of a
platelet count threshold of
< 10,000/µL for prophylactic transfusions, and issues related to the optimal
type of platelet product and dose of platelets. The authors make the important
point that although the risk of transmission of viral infections has decreased
markedly due to the addition of nucleic acid testing for hepatitis C and human
immunodeficiency virus (HIV),[1] sepsis due to bacterial contamination remains a
serious risk, particularly for the neutropenic patient.[2] The fever and chills
that occur within 6 hours after a platelet transfusion usually are associated
with nonhemolytic febrile transfusion reactions, but the more dangerous
possibility of bacterial sepsis from contamination should be considered,
particularly in the neutropenic patient, and treated empirically until bacterial
cultures prove otherwise.

Although efforts are being made to develop timely automated systems to detect
contaminating bacteria,[3] it is more likely that pathogen inactivation methods
will be the future mode of eliminating these organisms from platelet components.
Currently, a randomized trial is studying the clinical efficacy of platelets
that have been treated with the synthetic psoralen compound amotosalen
hydrochloride and long-wavelength ultraviolet light—a process that inactivates
HIV and hepatitis C virus, as well as bacteria and protozoa.[4] Obviously these
methods will increase the cost of platelet transfusions even further. However,
the 26% mortality associated with recognized bacterial infections and the
likelihood that platelets are a source of many unrecognized bacterial infections
support encouragement of these efforts.

Threshold Issues

The authors stress that the threshold of < 10,000 platelets/µL for
prophylactic platelet transfusion continues to be shown to be safe and leads to
a reduction in the use of platelet transfusion. The data in Figure 1 of the
Goodnough/DiPersio article, from a multicenter transplantation study published
in 1998, appear to show that almost two-thirds of the patients received platelet
transfusions prompted by the higher
< 20,000/µL threshold. The problem, of course, is not just that old habits
(the 20,000/µL trigger) die hard, but that other factors such as infection,
fever, and a rapid rate of decline in platelet count influence clinicians to
follow a more liberal platelet transfusion policy in individual patients.
Indeed, many controlled studies investigating the lower platelet count threshold
have used the higher threshold in patients with these complications.

The effect of these factors on corrected platelet increments supports the
clinical impression that more platelets are required in these settings. Other
issues include concerns regarding the accuracy of automated measurements of very
low platelet counts (due to red cell fragments that are counted), although the
reliability of automated platelet counts has improved significantly in recent
years.

ASCO Guidelines

The American Society of Clinical Oncology (ASCO) recently published
guidelines for platelet transfusion therapy in patients with cancer, based on
evidence from published trials and reports and the opinions of an expert
panel.[5] Many of the points made by Drs. Goodnough and DiPersio are reflected
in the ASCO guidelines, which are briefly summarized here:

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