Proton stereotactic radiotherapy for persistent adrenocorticotropin-producing adenomas.
BACKGROUND
Radiation therapy is a potentially curative treatment for corticotroph adenomas refractory to surgery. Protons have an advantage over photons (x-rays) by depositing energy at the target with no exit dose, providing a lower dose to adjacent normal tissues. Until recently, proton stereotactic radiotherapy (PSR) was available at only two U.S. centers; use will increase as proton facilities are under development.


OBJECTIVE
Our objective was to evaluate the efficacy and safety of PSR for persistent Cushing's disease (CD) and Nelson's syndrome (NS).


METHODS
This was a retrospective review of 38 patients (33 with CD and five with NS) treated between 1992 and 2005.


METHODS
All patients had transsphenoidal surgery without biochemical cure. Four had previous irradiation with photons. The patients with NS underwent bilateral adrenalectomy 29-228 months (median 40) before PSR.


METHODS
Single-fraction PSR was delivered at a median dose of 20 Cobalt Gray Equivalents (range 15-20) on 1 treatment day.


METHODS
Complete response (CR) was defined as sustained (> or =3 months) normalization of urinary free cortisol off medical therapy. CR in NS was based on normalization of plasma corticotropin.


RESULTS
At a median follow-up of 62 months (range 20-136), CR was achieved in five patients (100%) with NS and 17 (52%) patients with CD. Among all patients with CR, median time to CR was 18 months (range 5-49). No secondary tumors were noted on follow-up magnetic resonance imaging scans, and there was no clinical evidence of optic nerve damage, seizure, or brain injury. There were 17 patients (52%) who developed new pituitary deficits.


CONCLUSIONS
PSR is effective for patients with persistent corticotroph adenomas with low morbidity after a median follow-up of 62 months; longer follow-up is warranted for late radiation-related sequelae.
Petit
Joshua H
JH
Department of Radiation Oncology, Massachusetts General Hospital, 100 Blossom Street, Cox 347, Boston, Massachusetts 02114, USA.
Biller
Beverly M K
BM
Yock
Torunn I
TI
Swearingen
Brooke
B
Coen
John J
JJ
Chapman
Paul
P
Ancukiewicz
Marek
M
Bussiere
Marc
M
Klibanski
Anne
A
Loeffler
Jay S
JS
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000652:urine; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009347:Nelson Syndrome / Q000601:surgery* / Q000652:urine; D047748:Pituitary ACTH Hypersecretion / Q000601:surgery* / Q000652:urine; D061766:Proton Therapy; D016634:Radiosurgery / Q000379:methods*; D012074:Remission Induction; D012189:Retrospective Studies
D006854:Hydrocortisone