Linear accelerator radiosurgery for pituitary macroadenomas

Abstract

BACKGROUND. A prospective study was conducted to assess the efficacy and side effects of linear accelerator (LINAC)‐based radiosurgery (RS) performed with a reduced dose of therapeutic radiation for patients with surgically inaccessible pituitary macroadenomas. METHODS. From August 1990 through January 2004, 175 patients with pituitary macroadenomas were treated with LINAC‐RS according to a prospective protocol. To minimize the risk for radiation‐induced damage of the pituitary function, the therapeutic dose to be applied was limited to 20 grays. RESULTS. Among 175 patients, 142 patients who had a minimum follow‐up of 12 months (mean ± standard deviation, 81.9 ± 37.2 months) were included in the current study. The local tumor control rate was 96.5%, and the tumor response rate was 32.4%. The mean time (± standard deviation) from LINAC‐RS to normalization of pathologic hormone secretion was 36.2 ± 24.0 months. The probability for normalization was 34.3% at 3 years and 51.1% at 5 years. The frequency of endocrine cure (defined as the normalization of hormone secretion without specific medication intake) was 35.2% (mean ± standard deviation time to cure, 42.1 ± 25.0 months). Patients with Cushing disease had a statistically significant greater chance of achieving a cure (P = .001). Side effects of LINAC‐RS were deterioration of anterior pituitary function (12.3%), radiation‐induced tissue damage (2.8%), and radiation‐induced neuropathy (1.4%). CONCLUSIONS. LINAC‐RS using a lower therapeutic radiation dose achieved local tumor control and normalization or cure of hormone secretion comparable to the results achieved with γ‐knife RS. Compared with the latter, the time to normalization or endocrine cure was delayed, most probably as a result of dose reduction. However, the lower therapeutic radiation dose did not prevent radiation‐induced damage of pituitary function completely. Cancer 2006. © 2006 American Cancer Society.

The role of stereotactic radiosurgery in the multimodal management of growth hormone–secreting pituitary adenomas

“…16 Using the aforementioned strict criteria for hormonal remission, the range of endocrinological normalization was 17% to 82%, and an additional 4% to 47% of patients achieved hormonal control following radiosurgery. 2,4,5,14,16,21,33,[45][46][47]53,54,57,58 For instance, Pollock et al 45 observed an endocrinological remission rate of 67% and Ikeda et al…”

“…Using LINAC-based SRS, Voges et al 58 reported a true remission rate of 37.5% and an additional endocrinological control rate of 47% in their series of 64 patients with acromegaly. When more lenient definitions were employed, the range of hormonal remission rates was 0 to 100% while rates of endocrinological control ranged from 8% to 100% at the time of the latest follow-up.…”

“…Jagannathan et al 18 reported that 92% of patients with adequate radiographic follow-up demonstrated a decrease in tumor size following GKS and that an additional 6% showed no change in tumor volume. Voges et al 58 treated 64 patients with acromegaly with LINAC-based SRS and reported that 23% experienced a reduction in tumor volume while 73% had tumors that did not change significantly in size. To date, the largest series evaluating the use of the CyberKnife in the treatment armamentarium of acromegaly is by Roberts et al …”

Early versus late Gamma Knife radiosurgery following transsphenoidal resection for nonfunctioning pituitary macroadenomas: a matched cohort study

“…Stereotactic radiosurgery is a safe, viable management option for patients who receive subtotal resections and patients with recurrent nonfunctioning macroadenomas, or, less commonly, as an initial treatment for patients with high surgical comorbidities. 4,[23][24][25][26]28,33,35,37,45,[47][48][49][51][52][53]61,65 Stereotactic radiosurgery helps reduce some of the risks of conventional radiotherapy, including hypopituitarism, radiation-induced tumors, carotid stenosis, and stroke, as well as neurocognitive side effects. 1,30,38,39,56 Gamma Knife radiosurgery (GKRS) is highly effective at preventing radiographic progression of residual and recurrent adenomas.…”

“…4,14,17,20,[23][24][25][26]28,29,33,35,37,40,41,45,[47][48][49][50][51]53,56,61,63,65 While stereotactic radiosurgery confers a high rate of tumor control (approximately 90%) and a low rate of neurological deficits, the promising results of adjuvant GKRS are largely byproducts of single-center retrospective studies. 4,17,20,[23][24][25][26]28,29,33,35,37,41,45,[47][48][49]51,55,61,65 More recently, a large-scale multicenter study proposed a strong benefit-to-risk profile of GKRS for patients with recurrent or residual growing nonfunctioning pituitary adenomas. 53 Despite such findings, a prominent challenge remains in establishing...…”