SAN DIEGO – Insulinlike growth factor I level was not useful as a marker of growth hormone deficiency or altered body composition in a retrospective review of a large cohort of adult survivors of childhood cancers.
Late cancer treatment–related complications – metabolic syndrome, osteogenic side effects, thyroid dysfunction, and growth hormone deficiency – are increasing as a result of increased childhood cancer survivorship; 1 in 640 young adults is now a survivor of childhood cancer, she said.
Dr. Karin Blijdorp
Insulinlike growth factor I (IGF-I) is often used as a marker for growth hormone deficiency, said Dr. Blijdorp of the department of pediatric oncology at Erasmus University, Rotterdam, the Netherlands. Low IGF-I has been associated with a high body mass index and high visceral fat percentage, she said. Because BMI, dual x-ray absorptiometry (DXA), and waist-hip ratio are limited in their ability to determine body composition, "it would be useful to have an easy-to-measure serum marker, such as IGF-I, that predicts alterations in body composition, she added.
Dr. Blijdorp and her associates retrospectively reviewed 610 adult childhood cancer survivors who were treated at the university. Their median age at diagnosis was 6 years and the median follow-up time was 18 years. The researchers reviewed IGF-I z scores, anthropometrical measures, growth hormone–stimulation tests in patients with clinical suspicion of growth hormone deficiency, and measures of body composition on DXA.
About 30% of the patients had leukemia. Of the 610 survivors, 158 had cranial irradiation. A history of cranial irradiation was associated with a higher incidence of metabolic syndrome, with an increased BMI, waist-hip ratio, visceral fat percentage, and total body fat percentage, as well as lower lean body mass, Dr. Karin Blijdorp said at the annual meeting of the American Society of Hematology.
Significantly lower IGF-I z-scores (P less than .001) were noted in the acute leukemia survivors who had cranial irradiation (25 Gy; range, 24-25 Gy) and the brain tumor survivors who had local irradiation (42 Gy; range, 35-54 Gy). Compared with survivors who did not undergo cranial irradiation, survivors who underwent cranial irradiation also had lower height standard deviation scores (P less than .001), higher BMI (P less than .01), higher waist-hip ratios (P less than .001), higher visceral fat percentages (P less than .001), higher total body fat percentages (P less than .001), and lower lean body mass (P less than .001).
IGF-I was not strongly correlated with BMI (r = 0.12; P = .04), waist-hip ratio (r = 0.15; P = .01), total fat percentage (r = 0.14; P = .02), and lean body mass (r = 0.15; P = .01).
Among survivors who had low IGF-I levels and received growth hormone stimulation, IGF-I z scores did not did not significantly differ between those with and without severe growth hormone deficiency (P = .39).
Dr. Blijdorp said that she had no relevant financial conflicts to disclose.