Long-term outcomes studied for stem cell transplant recipients

Improved techniques and supportive care have resulted in a growing number of long-term survivors of stem cell transplants, though little is known about the impact transplants have on patients’ lives long after treatment. To find the answers, researchers from the City of Hope Cancer Center and the University of Minnesota assessed 854 cancer patients that had undergone stem cell transplants, taking a detailed look at the aftereffects of the procedure in the years following the transplant. Their results will be published in the June 1, 2005, issue of Blood, the official journal of the American Society of Hematology.

All study patients had survived at least two years post-transplant, with more than 70 percent surviving through the study’s completion. The majority of study deaths occurred within five years of the transplant, but for those who survived past the fifth anniversary of their transplant, the risk of death lessened each year thereafter. Only eight deaths were recorded for those who underwent a transplant 10 years prior, and none were recorded after 15 years. In fact, for some patients – including those who had a transplant for acute myeloid leukemia and all patients with any disease who had a standard risk (as opposed to high risk) of relapse at the time of transplantation – mortality at the 10-year mark was similar to that of the general population.

Further analysis highlighted the most likely causes for death in those patients that did not survive and hinted at ways that such deaths might be minimized. For those patients who died during the study period, the main cause was a recurrence of the original disease, followed by deaths due to secondary cancers. Relapse-related mortality was increased among patients with Hodgkin’s disease, non-Hodgkin’s lymphoma, and acute lymphoblastic leukemia. However, those who had undergone total body irradiation in preparation for the transplant were at a decreased risk for relapse-related death. Mortality not related to relapse was increased in patients who had received the chemotherapy drug carmustine as part of their preparative regimen and among patients who had received a transplant with peripheral blood stem cells, as opposed to stem cells from the bone marrow.

In addition to survival, the researchers wanted to study the quality of life patients had after transplant. To that end, 374 patients from the original group also participated in a follow-up survey investigating issues such as marital status, insurance coverage, education, income, and employment. For comparison, siblings of the participants completed the same questionnaire. The researchers found that the transplant survivors were more likely to report a health problem preventing them from holding a job when compared to the sibling group, especially the older survivors. Transplant participants were also more likely to report difficulty in obtaining or retaining health or life insurance (around 30 percent versus 5 percent). Other factors studied were at a level comparable to the non-transplanted counterparts.

“The results of this study will have a great impact on predicting long-term outcomes for the thousands of patients who receive stem cell transplants every year,” said Smita Bhatia, M.D., M.P.H., a staff physician at the City of Hope Cancer Center and lead author of the study. “This sets the stage for the study of interventions that could decrease patient deaths years after treatment. For those most at risk, perhaps better therapeutic options are needed.”

This work was supported in part by R01 CA078938 from the National Cancer Institute as well as The Leukemia & Lymphoma Society Clinical Scholar Award 2191-02.