Introduction: A joint late effects clinic for follow-up of survivors of childhood cancer has been in operation in our institution since 1995. In patients who have undergone cranial irradiation, dynamic anterior pituitary function testing using a standard insulin tolerance test (ITT) or, if contraindicated, a glucagon or arginine/GHRH test was undertaken at around five yearly intervals.
Methods: Case note review was undertaken for 24 patients (male: female ratio 1:1) who underwent cranial irradiation for ALL (age of diagnosis 5.8±3.6 years). 4/24 patients defaulted from adult clinic follow-up. 12/20 patients under follow-up had undergone more than one dynamic assessment of pituitary function.
Results: Average time following cranial irradiation to first dynamic pituitary function testing was 17.1 ± 4.8(10-26) years and at this point 65% of patients were GH deficient as defined by a peak GH <7 mcg/l. There was no difference between peak GH during the first and second dynamic test (P=0.53) and only one further patient was found to be GH deficient at the second dynamic test (20yrs post cranial irradiation). 5/20 patients were on adult GH replacement therapy. Mean time between cranial irradiation and starting adult GH therapy was 16.8±8.5 yrs. Those patients with biochemical GH deficiency who were not started on GH replacement therapy were asymptomatic and did not satisfy NICE AGDHA criteria. 3/10 males under follow-up were on testosterone replacement therapy, all had undergone testicular irradiation. No patients had any other pituitary hormone deficiencies or required other hormone replacement therapy.
Conclusions: Between 10 and 26 years following cranial irradiation for ALL 65% of patients developed biochemical GH deficiency illustrating the importance of well organised long-term endocrine follow-up for this patient group. However, continued repeated dynamic pituitary function testing may be unnecessary as there was no deterioration in peak GH concentrations during subsequent tests. The optimum time interval for initial dynamic pituitary function assessment remains unclear.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.