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Factors Associated With Endocrine Deficits After Stereotactic Radiosurgery of Pituitary Adenomas

Leenstra, James L. MD; Tanaka, Shota MD; Kline, Robert W. PhD; Brown, Paul D. MD; Link, Michael J. MD; Nippoldt, Todd B. MD; Young, William F. Jr MD; Pollock, Bruce E. MD

Neurosurgery:
doi: 10.1227/01.NEU.0000370978.31405.A9
Clinical Studies: Editor's Choice
Abstract

OBJECTIVE: To analyze the factors associated with anterior pituitary deficits after pituitary adenoma stereotactic radiosurgery (SRS).

METHODS: The tumor, pituitary stalk, and pituitary gland were segmented on the dose plans of 82 patients (secreting tumors, n = 53; nonsecreting tumors, n = 29) for dose-volume analysis. No patient had undergone prior radiation therapy and all patients had at least 12 months of endocrinological follow-up (median, 63 months; mean, 69 months; range, 13–134).

RESULTS: Thirty-four patients (41%) developed new anterior pituitary deficits at a median of 32 months (range, 2–118) after SRS. The risk of developing new anterior pituitary deficits was 16% and 45% at 2 and 5 years, respectively. Multivariate analysis of the entire group showed that poor visualization of the pituitary gland (hazard ratio [HR] = 2.63, 95% confidence interval [CI] = 1.10–6.25, P = .03) was associated with a higher rate of new anterior pituitary deficits. Dosimetric analysis of 60 patients whose pituitary gland could be clearly identified showed that increasing mean pituitary gland radiation dose correlated with new anterior pituitary deficits (HR = 1.11, 95% CI = 1.02–1.20, P = .02). New anterior pituitary deficits stratified by mean pituitary gland radiation dose: ≤7.5 Gy, 0% (0/7); 7.6 to 13.2 Gy, 29% (7/24); 13.3 to 19.1 Gy, 39% (9/23); >19.1 Gy, 83% (5/6).

CONCLUSION: New endocrine deficits after pituitary adenoma radiosurgery were correlated with increasing radiation dose to the pituitary gland. Methods that limit the radiation dose to the pituitary gland during SRS may increase the probability of preserving pituitary function.

In Brief

OBJECTIVE: To analyze the factors associated with anterior pituitary deficits after stereotactic radiosurgery for pituitary adenoma. METHODS: The tumor, pituitary stalk, and pituitary gland were segmented on the dose plans of 82 patients (secreting tumors, n = 53; nonsecreting tumors, n = 29) for dose-volume analysis. No patient had undergone prior radiation therapy and all patients had at least 12 months of endocrinological follow-up (median, 63 mo; mean, 69 mo; range, 13–134). RESULTS: Thirty-four patients (41%) developed new anterior pituitary deficits at a median of 32 months (range, 2–118) after SRS. The risk of developing new anterior pituitary deficits was 16% and 45% at 2 and 5 years, respectively. Multivariate analysis of the entire group showed that poor visualization of the pituitary gland (hazard ratio [HR] = 2.63, 95% confidence interval [CI] = 1.10–6. 25, P =.03) was associated with a higher rate of new anterior pituitary deficits. Dosimetric analysis of 60 patients whose pituitary gland could be clearly identified showed that increasing mean pituitary gland radiation dose correlated with new anterior pituitary deficits (HR = 1.11, 95% CI = 1.02–1 .20, P = .02). New anterior pituitary deficits stratified by mean pituitary gland radiation dose: ≤7.5 Gy, 0% (0/7); 7.6 to 13.2 Gy, 29% (7/24); 13.3 to 19.1 Gy, 39% (9/23); >19.1 Gy, 83% (5/6). CONCLUSION: New endocrine deficits after pituitary adenoma radiosurgery were correlated with increasing radiation dose to the pituitary gland. Methods that limit the radiation dose to the pituitary gland during SRS may increase the probability of preserving pituitary function.

Author Information

Department of Radiation Oncology, Mayo Clinic College of Medicine, Rochester, Minnesota (Leenstra) (Kline) (Brown)

Department of Neurological Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota (Tanaka) (Link)

Department of Endocrinology, Diabetes, Nutrition and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota (Nippoldt) (Young)

Departments of Neurological Surgery and Radiation Oncology, Mayo Clinic College of Medicine, Rochester, Minnesota (Pollock)

Reprint requests: Bruce E. Pollock, MD, Department of Neurological Surgery, Mayo Clinic, Rochester, MN 55905. E-mail: pollock.bruce@mayo.edu

Received, January 15, 2009.

Accepted, January 11, 2010.

Copyright © by the Congress of Neurological Surgeons