Patients often develop hormone deficiencies after cranial radiotherapy, most commonly in growth hormone (GH), said Dr. Georg Brabant and colleagues from the Manchester Academic Health Science Center in their report.
GHRT might improve fatigue and memory problems in brain tumor survivors, but its safety isn't clear -- "based largely on the potential mitogenic action of GH and its target hormone, IGF-1," the researchers wrote online June 29 in the Journal of Clinical Endocrinology and Metabolism.
For their current study, they looked at patients who received GHRT for at least 12 months after cranial irradiation, comparing them to controls who received cranial radiotherapy without GH. The two groups were matched for radiotherapy date, age, site of primary diagnosis, radiation dose, and fractionation, and included 110 patients each.
The mean age at primary diagnosis was 33 for patients and 29 for controls; more than half the patients were children under age 16. The average duration of GH replacement was eight years.
During a median follow-up of nearly 15 years, six tumors recurred in the GH group and eight in the control group. Five GHRT patients and three controls developed secondary tumors. Neither difference was significant.
Mortality was 6.4% in the GHRT group and 13.6% in the control group (p = 0.03).
Strengths of the study, Dr. Brabant and his team said, include the fact that all patients were treated at the same center, "which allows us to analyze a much more homogenous dataset than previously published studies, which mainly recruited using a multicenter approach." Also, they added, they used imaging data to confirm and date the development of secondary neoplasms and tumor recurrences.
"In conclusion, due to the highly controlled analytical approach, the long follow-up, and the long-term GH exposure, the present study strongly supports the notion that the risk of any GH-dependent effect on secondary tumor growth is low," the researchers wrote. "Because radiation treatment alone substantially increases the risk of secondary neoplasms, brain scans before initiation of GHRT remain mandatory to exclude any preexisting pathology."
J Clin Endocrinol Metab 2011.
Last Updated: 2011-07-28 17:30:25 -0400 (Reuters Health)
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