Long Term Follow-Up of Patients with Cushing's Disease Treated by Interstitial Irradiation

Abstract

The first 86 patients with Cushing's disease treated with interstitial irradiation (by needle implantation) as the sole therapy were reviewed. In the 82 patients who were reassessed 1 yr after treatment 63 (77%) achieved remission. This study comprises the outcome and complications in the 54 patients who had a remission and whom we were able to follow. The follow-up period ranged from 3-26 yr (mean, 10.5) from the time of remission. No instance of clinical or radiological relapse has occurred. Of these 54 patients, yttrium-90 alone was used in 32, of whom 12 (37%) required corticosteroid or T4 replacement therapy in a mean time of 3.5 months; in 7 of these 12 we elected to give an ablative dose. Gold-198 alone was used in 15 patients, of whom 7 (47%) developed hypopituitarism in a mean time of 76 months. Both isotopes were used in 7 patients. A diurnal serum cortisol rhythm was found in 28 of the 31 patients who were not receiving corticosteroid therapy. In 5 of the 7 patients with an initially abnormal pituitary fossa, serial radiological studies revealed remodelling in 3. There have been no complications in the last 17 years. Pituitary implantation with yttrium-90 is an effective alternative to transsphenoidal hypophysectomy, with a high remission rate, no recurrence (as yet), no operative complications, and avoidance of hormone replacement in the majority.

Radiation-induced hypopituitarism

“…Radiation-induced 61-100% Sensitive, 90-96% specific for a cut-off of 500 nmol/l (Rasmuson et al 1996, Gerritsen & Vermes 1997, Ambrosi et al 1998, Mayenknecht et al 1998, Abdu et al 1999, Tordjman et al 2000, Dorin et al 2003 Recent meta-analysis showed diagnostic superiority of LDSST over SST in secondary adrenal insufficiency ( Gold standard for the evaluation of secondary adrenal insufficiency Some authors advocate higher cut-offs of 550 nmol/l (Stewart et al 1998, Tuchelt et al 2000 or 580 nmol/l (Mukherjee et al 1997) Rare cases may be missed by the ITT (Tsatsoulis et al 1988). Clinical judgement should decide on further testing Contraindicated in patients with stroke, epilepsy, coronary heart disease or heart failure Test only valid if glucose nadir !2.2 mmol/l, close supervision required (Greenwood et al (Meikle et al 1969, Spiger et al 1975, Feek et al 1981, Fiad et al 1994, Berneis et al 2002 (Sandler et al 1987, Littley et al 1989. Meanwhile, observational studies have failed to show an increase in PRL levels after sellar brachytherapy (Clark et al 1983).…”

The epidemiology of endocrine tumours.

“…This might be explained by a combination of increased awareness and precision of diagnosis, or may be a true increase in incidence. The disease is more common in women (Howlett et al 1986) and is associated with a striking increase in mortality particularly due to vascular disease (Standardised Mortality Ratio) (Sandler et al 1987). Persistence of glucose intolerance or hypertension after treatment of Cushing's disease conveys a poorer prognosis (Etxabe & Vazquez 1994).…”

Pitfalls in the management of Cushing’s disease

“…79,80 LINAC radiosurgery has been shown to be an effective and safe treatment with minimal pituitary insufficiency in persistent or recurrent CD following TSS. 81 Interstitial irradiation is an effective alternative to transsphenoidal hypophysectomy, 82 while proton beam therapy can be used alone or in combination with unilateral adrenalectomy.…”