Growth Hormone Helps Childhood Stem Cell Transplant Survivors Grow Taller, Responses Vary

A nationwide Japanese study has found that growth hormone therapy can improve adult height in children who develop growth impairment after hematopoietic stem cell transplantation, while also revealing that the treatment’s benefits vary sharply according to the therapies and complications surrounding transplantation. The findings suggest that survivors of childhood cancer and serious nonmalignant diseases may continue gaining height for years after treatment begins, but that some patients face biological barriers that limit their response.

Hematopoietic cell transplantation, commonly known as HCT, replaces damaged or diseased blood-forming cells with healthy stem cells. It can be lifesaving for children with leukemia, other cancers, inherited blood disorders and immune-system diseases. As survival rates have improved, however, physicians have increasingly recognized that the end of treatment does not necessarily mark the end of its consequences. Short stature and impaired growth are among the most common long-term effects observed in children who undergo transplantation.

A research team from the Japanese Children’s Cancer Group, led by investigators at Hiroshima University, examined how growth hormone therapy affects final adult height in childhood HCT survivors diagnosed with post-transplant short stature. The researchers conducted a nationwide, multicenter retrospective cohort study, collecting information on patients’ growth patterns, transplant histories, medical complications and treatment responses. Their results were published in Frontiers in Endocrinology on May 20, 2026.

The study included 268 patients, with final adult height data available for 171. Among those with documented final height measurements, 58 had received growth hormone, while 113 had not. The investigators compared final height using standard deviation scores, or SDS, a statistical measure that shows how a person’s height differs from the average for individuals of the same age and sex. They also analyzed factors including age at diagnosis, age at transplantation, sex, underlying disease, transplant type, radiation exposure and transplant-related complications.

Patients treated with growth hormone generally achieved better final height outcomes than those who did not receive the therapy. Growth hormone, or GH, is a protein produced by the pituitary gland that stimulates the liver and other tissues to release insulin-like growth factor 1, known as IGF-1. This hormone promotes the multiplication and maturation of growth-plate cells in long bones. When GH signaling is insufficient, or when the growth plates remain responsive but the body lacks adequate stimulation, medical GH replacement can accelerate linear growth.

The Japanese study suggests that GH therapy may work differently in HCT survivors than it does in children with classical growth hormone deficiency. In many conventional cases, the most rapid increase in height occurs relatively soon after treatment begins, followed by a gradual slowing as the child approaches skeletal maturity. In the transplant-survivor group, however, height gains sometimes continued to accumulate for five years or longer, with additional improvement still visible at final adult height. This prolonged response may reflect the complex, delayed effects of transplantation, prior chemotherapy, radiation and chronic illness on the growth plates and endocrine system.

The strongest negative predictor of final height was total body irradiation, or TBI. This conditioning treatment is used before some transplants to destroy residual cancer cells and suppress the recipient’s immune system, reducing the risk that the new stem cells will be rejected. However, radiation can directly damage the growth plates, which are regions of cartilage responsible for the lengthening of bones during childhood. It can also affect the hypothalamus and pituitary gland, disrupting the hormonal signals that regulate growth. These effects may help explain why patients exposed to TBI showed more limited height outcomes, even when treated with GH.

The investigators also identified differences associated with transplant type and chronic graft-versus-host disease, a complication in which donor immune cells attack the recipient’s tissues after an allogeneic transplant. Such inflammation can affect multiple organs, alter nutrition and physical development, and require prolonged treatment with corticosteroids or other immunosuppressive drugs. The contrast between allogeneic transplants, which use donor cells, and autologous transplants, which return the patient’s own previously collected cells, further suggests that more than one biological pathway contributes to post-transplant growth failure.

Because the study was retrospective and not a randomized clinical trial, it cannot prove that GH therapy alone caused the observed improvement. Patients who received treatment may have differed from untreated patients in ways that influenced their growth, and the availability of final height data was incomplete. Even so, the findings offer important evidence for long-term survivorship care. The authors emphasize that growth monitoring should continue for years after transplantation and that treatment decisions should account for radiation exposure, chronic GVHD, transplant type, pubertal development and other endocrine risks. The next challenge is to determine why some survivors respond strongly to GH while others gain little, allowing physicians to identify high-risk patients earlier and tailor therapy more precisely. For children who survive transplantation, the goal is increasingly extending beyond survival itself: it is helping them reach their biological growth potential and maintain health throughout adulthood.

News Publication Date: 20-May-2026

Web References: https://doi.org/10.3389/fendo.2026.1831711

References: Shimomura, M. et al. “Growth hormone therapy after hematopoietic cell transplantation in childhood: a nationwide survey and longitudinal cohort study.” Frontiers in Endocrinology, published May 20, 2026. DOI: 10.3389/fendo.2026.1831711