WASHINGTON--Although the role of erythropoietin, or epoetin (Epogen,
Procrit), in the treatment of chemotherapy-induced anemia is
generally well known and accepted, its potential for prophylactic use
to prevent the development of anemia in cancer patients remains at
Nonetheless, recent research has provided a greater understanding of
which cancer patients are likely to benefit from receiving
erythropoietin before or during chemotherapy, Carole R. Chambers told
the Sixth International Symposium on Oncology Pharmacy Practice
"Patients at highest risk for transfusion are anemic prior to
chemotherapy, and usually have lung cancer or leukemia," said
Ms. Chambers, director of pharmacy, Alberta Cancer Board.
In Canada, research has indicated that the most likely candidates for
early treatment with erythropoietin are patients who have symptomatic
anemia affecting their functional capacity or quality of life; those
who have a low baseline hemoglobin at the start of chemotherapy; and
those who have a decline in their baseline, whatever the initial
reading, of 20 g during chemotherapy.
"If one looks at the hemoglobin before the patient starts
chemotherapy and again just before they get their second
chemotherapy, and if it has dropped by 20 g, there is an 86%
prediction of transfusion," Ms. Chambers said.
Abnormal Feedback Response
Anemia in cancer patients is characterized by shortened red blood
cell survival, poor reutilization of iron, and an inadequate
erythropoietin response. Normally, erythropoietin is released into
the blood in response to low oxygen levels and stimulates an
increased production of erythrocytes. "Cancer patients do not
show the normal feedback response to increase their erythropoietin
production," Ms. Chambers said.
The aim of erythropoietin therapy is to increase a patients
quality of life and reduce the need for transfusion. However, some
transfusions may still be necessary because it takes several days for
injected erythropoietin to rev up the bodys response mechanism.
Oncologys growing experience with erythropoietin has quieted
some serious initial concerns. For example, no evidence of tolerance
has emerged. And despite early fears that erythropoietins role
as a growth factor might cause cancers to grow more rapidly, no such
tumor stimulation has been shown, Ms. Chambers said.
"It is really important for patients to know that the early,
significant side effects seen in the renal disease population
(hypertension, seizures, thromboembolic events) have not been seen in
the cancer population," she said.
Experience has also shortened the time needed to evaluate the
effectiveness of erythropoietin in cancer patients and has offered
guidance on when to stop such therapy. Until 1995, the rule was to
evaluate after 8 weeks; now, evaluations more commonly take place at
4 weeks, and a few centers are trying to determine if a meaningful
evaluation can be made in 2 weeks.
"If you havent gotten a response at 4 weeks, you may turn
those nonresponders into responders by doubling their dose and
evaluating them again in 4 weeks," Ms. Chambers said. "And
if you still have not gotten a response, plan to discontinue the
erythropoietin therapy. You are unlikely to get a response."
The issue of iron supplements continues to spark debate, with some
experts arguing that virtually all anemic patients need additional
iron. "But iron is not a great thing to tolerate as a
patient," Ms. Chambers said. "I think the jury is still out
on iron supplementation."
It is important that oncologists make clear to patients that while
erythropoietin may improve their functional status and quality of
life, it does not treat their underlying disease. "Thus,"
she said, "although they may feel better, this in no way
indicates that their cancer is cured."
Ms. Chambers forecasts greater use of erythropoietin in a greater
variety of cancers. And she predicts that very soon, important
clinical questions will focus on which specific subsets of cancer
patients will most benefit from erythropoietin therapy, in part
because of the cost of the treatments. "Our challenge is to make
sure we focus therapy on patients most likely to benefit and
discontinue its use if they are not going to benefit," she concluded.