For the first time, researchers have evaluated the immunity of long-term bone-marrow and stem-cell transplant survivors. The study found that for patients surviving 20 to 30 years after transplantation living a normal life, free of frequent infections is possible. Results from this study are reported in the Dec. 15 issue of the journal Blood.
Dr. Jan Storek, a researcher at the Fred Hutchinson Cancer Research Center and acting assistant professor at the University of Washington, evaluated 72 former patients who are 20 to 30 year survivors. These individuals are recognized as the longest bone-marrow and stem-cell transplant survivors in the world.
Quality of life after bone-marrow or stem-cell, also known as hematopoietic, transplantation has long been a concern, especially for those who underwent bone marrow transplantation in the early days. Today, hematopoietic transplantation is considered the best chance for cure for people with leukemia. Transplantation works by destroying a patient's diseased or damaged marrow and replacing it with healthy marrow or stem-cells. Due to the high-dose chemotherapy and radiation therapy patients experience, cell counts drop to very low levels creating a highly immune-compromised state. Although a patient's cell counts will reach normal level within weeks, it can take much longer for the immune system to function normally. In addition, patients who have undergone a hematopoietic transplant much re-vaccinate. The recovery period varies from patient to patient, and for some can take a long time. During this time patients are susceptible to infections that can be debilitating, or even life threatening.
Storek hoped to better understand if former hematopoietic transplant patients are able to recover and sustain a normal life. To do this, he designed a questionnaire to survey former patients and their physicians about the occurrence of infections between the 16th and 30th survival years. As an additional source of information, the Storek reviewed medical records from the patients' primary physicians.
For the study, Storek evaluated 591 patient-years for the 72 patients. He found a total of 41 infections were reported, for an average of one infection every 14 years, discounting common colds. For people transplanted before the age of 18, the rate of infection was lower, averaging one infection every 18 years, and for those who underwent transplant after age 18 the rate of infection was one infection every 11 years.
According to Storek, infections were rare despite the fact that some patients suffered from conditions known to be associated with increased susceptibility to infections.
"We believe we captured a significant majority of serious infections, says Storek. "However, it is possible that minor infections were underreported due to the patients not recalling these infections."
In addition, blood samples to study immune cells were taken from 33 of the 72 patients. For most of the patients, the parameters for immunity were normal. Storek concluded that their immunity recovered to normal or near-normal by the time they were 20 years out from transplant. "We realize there may be another explanation of the results, says Storek. "Instead of a gradual improvement of their immunity over the first two decades after transplant, the patients may have had a good immune system early after transplant."
Moreover, the willingness of the patients and some of their marrow donors, who donated blood for this research, lead to an important scientific finding. For the first time it was proven that the transplanted hematopoietic cells and/or immune cells are good for at least 20 to 30 years. In conclusion, the researchers believe patients surviving more than 20 years are not significantly immunocompromised and these patients are comparable to people of similar age.
The Fred Hutchinson Cancer Research Center, home of two Nobel Prize laureates, is an independent, nonprofit research institution dedicated to the development and advancement of biomedical technology to eliminate cancer and other potentially fatal diseases. Recognized internationally for its pioneering work in bone-marrow transplantation, the Center's four scientific divisions collaborate to form a unique environment for conducting basic and applied science. The Hutchinson Center is the only National Cancer Institute-designated comprehensive cancer center in the Pacific Northwest and is one of 37 nationwide. For more information, visit the Hutchinson Center's Web site at www.fhcrc.org.
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