Stereotactic radiosurgery/radiotherapy for pituitary adenomas: a review of recent literature

Results of Treatment with Modern Fractionated Radiotherapy, Contemporary Stereotactic Radiosurgery, and Transsphenoidal Surgery in Nonfunctioning Pituitary Macroadenoma

BACKGROUND

To compare the effects of contemporary stereotactic radiosurgery (SRS), modern fractionated radiotherapy (FRT), and transsphenoidal surgery on nonfunctioning pituitary macroadenoma.

METHODS

We enrolled patients with nonfunctioning pituitary macroadenoma. To compare treatment outcomes, the patients were categorized into three groups according to the treatment modality: group 1, patients receiving modern FRT; group 2, patients receiving contemporary SRS; and group 3, patients receiving transsphenoidal surgery.

RESULTS

In total, 548 patients with nonfunctioning pituitary macroadenoma were selected for our study. Univariate and multivariate Cox regression analysis results indicated that the treatment modalities were significant independent prognostic factors. In multivariable Cox proportional hazard regression analysis, the adjusted hazard ratios (aHR; 95% confidence interval (CI)) of local recurrence were 0.27 (0.10-0.91) and 1.95 (1.25-2.37) for the SRS and transsphenoidal surgery cohorts, respectively, in comparison with the FRT cohort. The aHR (95% CI) of all-cause mortality was 1.03 (0.68-1.56) for the transsphenoidal surgery cohort in comparison with the FRT cohort, without statistical significance. However, the aHR (95% CI) of all-cause mortality was 0.36 (0.15-0.85) for the SRS cohort in comparison with the FRT cohort.

CONCLUSION

Contemporary SRS has optimal effects on local recurrence and survival compared with modern FRT and transsphenoidal surgery. Modern FRT is associated with more favorable local control and equal survival compared with transsphenoidal surgery.

Dosimetric impact of multileaf collimator leaf width according to sophisticated grade of technique in the IMRT and VMAT planning for pituitary adenoma lesion

We analyzed the difference in the dosimetric effect between 5-mm and 2.5-mm multileaf collimator (MLC) leaf width according to the sophisticated grades of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). Nineteen patients with pituitary adenomas were selected for this study. The treatment plans were performed according to the size of the MLC (5-mm and 2.5-mm MLC), the type of technique (IMRT and VMAT), and the sophisticated grades of each technique (5-field, 9-field, 13-field, 17-field technique in IMRT and 1-arc and 2-arc techniques in VMAT). The downsizing effects of MLC leaf width were analyzed using target volume coverage (TVC), conformity index (CI), dose gradient index (GI), and normal tissue difference 70% isodose line and 50% isodose line. Upon replacing the 5-mm MLC with the 2.5-mm MLC, TVC and CI improved by 1.30% and 1.36%, respectively, in total plans. The TVC and CI improved by 1.68% and 1.67% in IMRT, respectively, and by 0.54% and 0.72% in VMAT, respectively. TVC improved by 2.53%, 1.82%, 1.34%, and 0.94%, and CI also improved by 2.70%, 1.81%, 1.24%, and 0.94%, in 5-field, 9-field, 13-field, and 17-field IMRT, respectively. TVC improved by 0.66% and 0.43%, and CI also improved by 0.93%, and 0.52% in 1-arc and 2-arc VMAT, respectively. Regarding the target coverage, there were dosimetric benefits of a smaller MLC leaf width. However, the downsizing effect of the MLC leaf width decreased with the use of a more precise RT technique and a more sophisticated grade of the same technique.

[LAPAROSCOPIC BILATERAL ADRENALECTOMY FOR REFRACTORY CUSHING DISEASE: A CASE REPORT]

A 64-year-old man was diagnosed as having Cushing's disease due to multiple lumbar compression fracture in 2009. Although various treatments including three times transsphenoidal surgery and twice radiotherapy were performed, his serum cortisol level rose again and intractable cutaneous ulcer occurred. Just after discontinuation of medication to treat the progression due of severe hepatic dysfunction, deep vein thrombosis and pulmonary artery embolism occurred. To control the Cushing's disease, laparoscopic bilateral adrenalectomy was performed.

Safety and efficacy of fractionated stereotactic radiotherapy and stereotactic radiosurgery for treatment of pituitary adenomas: A systematic review and meta-analysis

Accumulated studies have not provided conclusive evidence in regards to the comparative efficacy and safety of fractionated stereotactic radiotherapy and stereotactic radiosurgery for treatment of pituitary adenomas. To address this issue, we performed a meta-analysis with eight studies identified from Medline, PubMed, Cochrane, Google Scholar, and published up to September 17, 2015. Eligible studies reported the disease control rate, endocrine cure rate (for functional adenomas), the rate of occurrence of new-onset hypopituitarism, and visual disturbance rate in patients treated with either stereotactic radiosurgery or fractionated stereotactic radiotherapy. Eight studies enrolled a total of 634 patients with pituitary adenoma, 273 patients underwent a stereotactic radiosurgery and 361 patients underwent fractionated stereotactic radiotherapy. No significant differences were found in efficacy measures, such as disease control rate and endocrine cure rate, between stereotactic radiosurgery and fractionated stereotactic radiotherapy (OR=1.156, p=0.666; OR=0.659, p=0.153, respectively). Additionally, meta-analysis of safety measures, such as the rate of new-onset hypopituitarism and visual disturbance rate, did not show significant differences between different treatments (OR=1.365, p=0.469; OR=0.872, p=0.845 respectively). In conclusion, both stereotactic radiosurgery and fractionated stereotactic radiotherapy have comparable efficacy and safety in the management of pituitary adenoma patients.

Curative effects of head γ-SRT for the treatment of functional pituitary macroadenoma

The aim of the study was to examine the curative effects and proper radiotherapy plan of head γ-stereotactic radiotherapy (γ-SRT) for the treatment of functional pituitary macroadenoma. Clinical samples of 30 patients that underwent γ-SRT (radiotherapy group) and 26 patients that underwent pituitary adenoma resection via single nasal-sphenoidal approach (surgery group) were analyzed retrospectively and their curative effects were compared. The results showed that in the radiotherapy group, 12 cases accepted single fraction irradiation, with an average maximum diameter of tumor body of 1.8±0.6 cm, average volume of 0.6±0.4 cm³, average dose of the central point of 52.6±18.7 Gy, average dose of the peripheral point of 24.7±10.2 mGy, and isodose curve of 50–70%. The remaining 18 cases accepted multiple fraction irradiation, with an average irradiation of 3.7±1.6 times, maximum average diameter of tumor body of 4.3±1.8 cm, average volume of 4.8±2.7 cm³, average dose of the central point of 24.6±12.5 Gy, average dose of the peripheral point of 13.6±7.4 mGy, and isodose curve of 50–70%. Following treatment, the tumor volumes of patients in the radiotherapy group that received single and multiple irradiation were significantly reduced and the visual acuity and visual field were improved (p<0.05). The two groups were followed up for an average of 3.8 years, and the follow-up results showed that differences of the two groups on the tumor control, mortality and hypopituitarism rates were not statistically significant (p>0.05). In addition, the incidence of complications of the radiotherapy group was significantly decreased as compared to that of the surgery group (p<0.05). In conclusion, γ-SRT was safe and effective for the treatment of functional pituitary adenomas. Its curative effects were equivalent to that of the microscopic single nasal-sphenoidal approach with fewer complications.

Gamma knife radiosurgery for Cushing's disease and Nelson's syndrome

PURPOSE

This paper presents our 18 years of experience in treating ACTH secreting adenomas (Cushing's disease and Nelson's syndrome) using the Leksell gamma knife (LGK) irradiation.

METHODS

Twenty-six patients with Cushing's disease were followed-up after LGK irradiation for 48-216 months (median 78 months). Seventeen patients had undergone previous surgery, in nine patients LGK irradiation was the primary therapy. Furthermore, 14 patients with Nelson's syndrome were followed-up for 30-204 months (median 144 months).

RESULTS

LGK treatment resulted in hormonal normalization in 80.7 % of patients with Cushing's disease. Time to normalization was 6-54 months (median 30 months). The volume of the adenoma decreased in 92.3% (in 30.7% disappeared completely). There was no recurrence of the disease. In all 14 patients with Nelson's syndrome ACTH levels decreased (in two patients fully normalized) their ACTH levels. When checked up 5-10 years after irradiation regrowth of the adenoma was only detected in one patient (9.1%), in 27.3% adenoma volume remained unchanged, in 45.4% adenoma volume decreased and in 18.2% adenoma completely disappeared. Hypopituitarism did not develop in any patient where the critical dose to the pituitary and distal infundibulum was respected.

CONCLUSION

LGK radiation represents an effective and well-tolerated option for the treatment of patients with Cushing's disease after unsuccessful surgery and may be valuable even as a primary treatment in patients who are not suitable for, or refuse, surgery. In the case of Nelson's syndrome it is possible to impede tumorous growth and control the size of the adenoma in almost all patients.

Development of a modified head and neck quality assurance phantom for use in stereotactic radiosurgery trials

An anthropomorphic head phantom, constructed from a water‐equivalent plastic shell with only a spherical target, was modified to include a nonspherical target (pituitary) and an adjacent organ at risk (OAR) (optic chiasm), within 2 mm, simulating the anatomy encountered when treating acromegaly. The target and OAR spatial proximity provided a more realistic treatment planning and dose delivery exercise. A separate dosimetry insert contained two TLD for absolute dosimetry and radiochromic film, in the sagittal and coronal planes, for relative dosimetry. The prescription was 25 Gy to 90% of the GTV, with ≤10% of the OAR volume receiving ≥8Gy for the phantom trial. The modified phantom was used to test the rigor of the treatment planning process and phantom reproducibility using a Gamma Knife, CyberKnife, and linear accelerator (linac)‐based radiosurgery system. Delivery reproducibility was tested by repeating each irradiation three times. TLD results from three irradiations on a CyberKnife and Gamma Knife agreed with the calculated target dose to within ± 4% with a maximum coefficient of variation of ±2.1%. Gamma analysis in the coronal and sagittal film planes showed an average passing rate of 99.4% and 99.5% using ±5%/3mm criteria, respectively. Results from the linac irradiation were within ±6.2% for TLD with a coefficient of variation of ±0.1%. Distance to agreement was calculated to be 1.2 mm and 1.3 mm along the inferior and superior edges of the target in the sagittal film plane, and 1.2 mm for both superior and inferior edges in the coronal film plane. A modified, anatomically realistic SRS phantom was developed that provided a realistic clinical planning and delivery challenge that can be used to credential institutions wanting to participate in NCI‐funded clinical trials.

PACS number: 87.55 ‐v

LINAC-radiosurgery for nonsecreting pituitary adenomas. Long-term results

BACKGROUND AND PURPOSE

Stereotactic linear accelerator-based radiosurgery (LINAC-RS) is increasingly used for microsurgically inaccessible or recurrent pituitary adenomas. This single-center study evaluates the long-term follow-up after LINAC-RS of nonsecreting pituitary adenomas (NSA).

PATIENTS AND METHODS

Between 1992 and August 2008, 65 patients with NSA were treated. Patient treatment and follow-up were conducted according to a prospective protocol. Indications for LINAC-RS were (1) tumor recurrence or (2) residual tumor. Three patients were treated primarily. For analysis of prognostic factors, patients were grouped according to epidemiological or treatment-associated characteristics.

RESULTS

A total of 61 patients with a follow-up ≥ 12 months (median 83 months, range 15-186 months, longest follow-up of published radiosurgery series) were evaluated with regard to their clinical, radiological, and endocrinological course. The median tumor volume was 3.5 ml (± 4.3 ml, range 0.3-17.3 ml) treated with a median surface and maximum dose of 13.0 Gy and 29.7 Gy, respectively. Local tumor control was achieved in 98%. One patient died of unrelated cause after 36 months and 1 patient developed a radiation-induced seizure disorder. Visual complications did not occur. In 37 of 41 patients (90.2%), pituitary function remained stable. Maximum dose to the pituitary ≤ 16 Gy and female gender were positive prognostic factors for the preservation of pituitary function.

CONCLUSION

LINAC-RS is a minimally invasive, safe, and effective treatment for recurrent NSA or microsurgically inaccessible residual tumor. LINAC-RS yielded a high rate of local long-term tumor control with a small number of radiation-induced side effects.

Recent advances in pituitary tumor management

PURPOSE OF REVIEW

Advances in the neurosurgical management of pituitary tumors have included the refinement of surgical access and significant progress in navigation technology to help further reduce morbidity and improve outcome. Similarly, stereotactic radiosurgery has evolved to become an integral part in pituitary tumors not amenable to medical or surgical treatment.

RECENT FINDINGS

The evolution of minimally invasive surgery has evolved toward endoscopic versus microscopic trans-sphenoidal approaches for pituitary tumors. Debate exists regarding each approach, with advocates for both championing their cause. Stereotactic and fractional radiosurgery have been shown to be a safe and effective means of controlling tumor growth and ensuring hormonal stabilization, with longer-term data available for GammaKnife compared with CyberKnife.

SUMMARY

The advances in trans-sphenoidal surgical approaches, navigation technological improvements and the current results of stereotactic radiosurgery are discussed.