BMI concerns raised for childhood stem cell transplantation survivors

By Lynda Williams, Senior medwireNews Reporter

Childhood survivors of hematologic malignancies treated with allogeneic hematopoietic stem cell transplantation (HSCT) should undergo long-term monitoring of their body mass index (BMI) and lean body mass, US researchers recommend.

"We suggest that dietary education and exercise counseling are essential to improve the physical status and overall health of survivors with the risk factors identified in this study," say Wing Leung (St Jude Children's Research Hospital, Memphis, Tennessee) and co-authors.

Over a median of 6.6 years of follow up, 179 patients, aged a median of 11.3 years at the time of transplantation, experienced a significant drop in their BMI z score, from 0.32 before HSCT to -0.60 after 10 years.

Of concern, dual-energy X-ray absorptiometry showed this decline was due to a significant decrease in lean mass, with levels significantly below population norms and decreasing over time. By contrast, the patients' z scores for fat mass remained within normal levels.

Overall, 4.5% of patients were underweight and 30.1% of patients were overweight or obese before HSCT, compared with 11.5% and 23.0% of patients 10 years after transplantation.

The researchers say that BMI score or category significantly predicted future BMI, noting that no underweight patient became obese, and no obese patient became underweight.

In addition, patients with limited or extensive chronic graft-versus-host disease (GVHD) were significantly more likely to develop a low BMI and lean body mass than those without the complication (odds ratio=3.5 and 4.1, respectively). Older age at time of HSCT and T-cell-depleted graft also significantly associated with low BMI after HSCT.

The team suggests that GVHD and total body irradiation - previously shown to alter leptin sensitivity - may explain their findings.

"Prospective endocrine evaluation, including not only growth hormone secretion, thyroid function, and sex hormone production but also hormonal regulation of glucose and lipid metabolism, will improve our understanding of the observed changes in body composition and their impact," comment Leung et al in the Journal of Clinical Oncology.

"The declines in BMI and lean mass persisted throughout the follow-up period. Therefore, health care providers should be alert to losses in not only BMI but also lean mass in these survivors and ensure early, appropriate intervention by a registered dietitian and physical therapist."

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