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  • Study Suggests Stem Cell Transplant Survivors At Increased Risk Of D

    STUDY SUGGESTS STEM CELL TRANSPLANT SURVIVORS AT INCREASED RISK OF DEVELOPING HEART DISEASE

    e! Science News
    Oct 3 2012

    Published: Wednesday, October 3, 2012 - 14:37 in Health & Medicine

    New research appearing online October 3 in Blood, the Journal of
    the American Society of Hematology (ASH), suggests that long-term
    survivors of hematopoietic cell transplants (HCT) are at an increased
    risk of developing heart disease risk factors such as high blood
    pressure, diabetes, and high cholesterol when compared to the general
    population. These risk factors, combined with exposure to pre-HCT
    therapy, contribute to a noticeably increased risk of heart disease
    over time. HCT, the transplantation of blood-forming stem cells from
    the bone marrow, circulating blood, or umbilical cord blood, is the
    primary treatment option for many patients with blood disorders. The
    healthy transplanted stem cells replace patients' damaged cells that
    caused their illness. Advances in transplantation strategies have
    contributed to marked improvements in patient outcomes, resulting
    in a growing number of long-term transplant survivors, many of whom
    struggle with one or more chronic, post-transplant health conditions.

    Previous researchers have speculated that survivors' exposure to
    potentially heart damaging pre-transplant chemotherapy and radiation
    or treatment for a life-threatening transplant complication known as
    graft-versus-host-disease (GVHD) can increase their risk of developing
    heart disease and its associated risk factors. However, there have
    been limited data to validate the contribution of pre-conditioning
    chemotherapy or radiation and GVHD to the eventual development of
    heart disease in long-term HCT survivors.

    "While we know that heart disease is a real concern for long-term
    HCT survivors, small sample sizes and a lack of long-term follow up
    in previous studies have only allowed us to look at a small piece of
    the puzzle of how this chronic condition develops in these patients,"
    said Saro H. Armenian, DO, MPH, the study's first author, Assistant
    Professor in the Division of Outcomes Research, and Medical Director of
    the Pediatric Survivorship Clinic in the Childhood Cancer Survivorship
    Program at City of Hope in Duarte, CA. "Our study sought to better
    determine the specific factors before and after transplant that can
    lead to heart disease in a large group of transplant recipients."

    In order to more thoroughly evaluate heart disease risk and development
    in HCT recipients, Dr. Armenian and his team of researchers designed
    a retrospective study to evaluate factors that may affect a survivor's
    risk of developing high blood pressure, diabetes, and high cholesterol
    after HCT. These factors included transplant recipients' exposure to
    pre-transplant chemotherapy and radiation, conditioning therapy for
    HCT, their type of HCT transplant, and whether they developed and
    were treated for GVHD post transplant.

    To better determine HCT survivors' incidence of high blood pressure,
    diabetes, and high cholesterol compared to the general population,
    researchers analyzed medical records of 1,885 patients who underwent
    a first-time HCT for a blood cancer at City of Hope between 1995
    and 2004 and had survived at least one year. The National Health
    and Nutrition Examination Survey was used to generate expected heart
    disease risk factor rates for the general population.

    Following their analysis, researchers found a higher prevalence of
    high blood pressure, diabetes, and high cholesterol in long-term HCT
    transplant survivors when compared to the general population. HCT
    conditioning with total body radiation was associated with a 1.5-fold
    increase in risk of developing diabetes and a 1.4-fold increase
    in risk of developing high cholesterol, regardless of HCT type, a
    finding that validates previous reports from long-term childhood and
    adult HCT survivors. While the mechanism by which total body radiation
    increases the risk of diabetes and high cholesterol in HCT recipients
    is not clear, previous studies have shown that abdominal radiation
    may contribute to known heart disease risk factors such as insulin
    resistance and an increase in belly fat in conventionally treated
    cancer patients. This evidence suggests that radiation-induced
    pancreatic or liver injury may play a role in an HCT transplant
    survivor's development of heart disease by increasing their risk for
    heart disease risk factors.

    Next, researchers assessed the role of transplant type on long-term
    HCT survivors' risk of developing key heart disease risk factors.

    After reviewing the data, researchers observed that those who had
    received transplanted stem cells from a donor (allogeneic HCT) were
    at a significantly higher risk of developing high blood pressure,
    diabetes, or high cholesterol after transplant than those who had
    received blood-forming stem cells from their own body (autologous
    HCT). Over the 10-year study period, 45.3 percent of allogeneic
    HCT recipients developed high blood pressure, 20.9 percent developed
    diabetes, and 50.5 percent developed high cholesterol; whereas only 32
    percent, 15.9 percent, and 43.3 percent of autologous HCT recipients
    developed these same conditions, respectively. Transplant recipients
    who had undergone an allogeneic HCT and who had experienced GVHD had
    the highest risk of developing heart disease risk factors, researchers
    concluded; 54.7 percent of this group developed high blood pressure,
    25.8 percent developed diabetes, and 52.8 percent developed high
    cholesterol.

    Not only did more allogeneic than autologous HCT recipients develop
    these heart disease risk factors over this time period, but they also
    developed them more quickly. Allogeneic HCT recipients developed high
    blood pressure and high cholesterol both at a median time to onset of
    2.5 months, compared with autologous HCT recipients who developed the
    same conditions at 3.7 years and 1.6 years, respectively. Allogeneic
    HCT recipients also developed diabetes more than two years earlier than
    autologous recipients (1.2 year median time to onset for allogeneic
    HCT recipients vs. 3.3 years for autologous transplant recipients).

    In addition to evaluating incidence rates of key heart disease risk
    factors in this large group of long-term HCT survivors, investigators
    also assessed their impact on survivors' subsequent development
    of heart disease. A total of 115 patients went on to develop heart
    disease at a median rate of four years after HCT. At 10 years post HCT,
    the cumulative incidence of post-HCT heart disease in all survivors
    was approximately 7.8 percent, with the rate exceeding 11 percent
    in the survivors with multiple heart disease risk factors. In those
    survivors with multiple heart disease risk factors and past exposure
    to cardiotoxic chemotherapy or radiation, the incidence rose to
    approximately 18 percent, demonstrating that certain pre-transplant
    therapeutic exposures compound HCT recipients' risk of developing
    heart disease.

    "Our findings show that the process of receiving a stem cell
    transplant alone increases a recipient's risk of developing heart
    disease; however, the type of transplant and whether the recipient was
    treated for GVHD can also increase that survivor's heart disease risk
    as well," said Dr. Armenian. "The results of this study demonstrate
    the importance of intervention strategies that can help mitigate
    these modifiable heart disease risk factors in transplant recipients
    before and after transplant, and we hope they can serve as a basis
    for creating a predictive model to identify those patients at highest
    risk of developing heart disease."

    Source: American Society of Hematology

    http://esciencenews.com/articles/2012/10/03/study.suggests.stem.cell.transplant.survivors.incr eased.risk.developing.heart.disease

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