Gamma system Surgery (GKS) for Intracranial Hemangiopericytomas (IHMP)
Neurosurgery Institution Beijing
[Outline] Objective: To evaluate the efficacy of GSK for Treatment of Recurrent Intracranial Hemangiopericytomas.
Methods: We retrospectively reviewed data for patients who underwent GKS in our institution. 5 patients underwent GKS for 7 discrete tumors. The mean volume of tumors was 3.2cm3. The mean radiation dose to the tumor margin was 12Gy. The mean radiation dose to the tumor center was 27.5Gy.
Results: The mean follow-up period was 10.2 months. According to images, one case had tumor free, 3 patients has tumor shrinkage and one patients had tumor enlargement; Total rate of tumor control was 80%.
Conclusions: Gamma system radiosurgery provided good local tumor control of hemangiopericytomas and substantially contributed to the comprehensive treatment modalities of IHMPs.
[Key words] Hemangiopericytomas, gamma system therapy, stererotactic radiosurgery
Hemangiopericytoma, a typical invasive tumor, are likely to have local recurrence and metastases. 5 patients were diagnosed hemangiopericytoma with pathological proofs. Some experiences were enriched for the treatment of IHMP
In this group, all 7 tumor lesions were proved pathologically hemangiopericytoma; the mean tumor volume was 3.2cm3 (range 0.33-8.6cm3); the mean peripheral dose was 12Gy (range 12-14Gy); the mean center dose was27.5Gy(range 23-35Gy); the mean period of follow-up was 10.2 months (range 5-12months); before radiosurgery the mean Karnofsky score was 70(range 30-90); after radiosurgery the mean Karnofsky score was 74(range 10-90); two patients underwent conventional radiotherapy after craniotomy and resection, two patients did not undergo conventional radiotherapy, and a patients had underwent GKS two time before he came to our center. From data of our follow-up, only one of 5 patients had no tumor control and his tumor still was intractable even if the patient underwent GSK 4 times and craniotomy and resection 1 time, furthermore this tumor was the largest among the seven tumors with obvious invasiveness. We assumed that: if we initially treated this tumor using surgery to decrease the radiation volume effectively, then stererotactic radiosurgery was applied to it, better outcome may be achieved. 4 of 5 patients were recurrent IHMP and a patient had metastases. In our group, rate of tumor control using GSK for IHMP was 80%. There was no statistical value for too small population. Clinical results were shown in table1
IHMP was grouped into intracranial meningiomas for the methods of classification, also called 2.3.4 angioreticuloma meningiomas or hemangioblastoma meningiomas. Hemangiopericytoma, a rare mesenchymal neoplasm with abundant blood flow, accounts for about <1% of all primary CNS tumors and about 2.4% of meningiomas .IHMP is characteristic of a neoplasm with an aggressive natural history , a tendency towards local recurrence and relatively frequent metastases outside the CNS. IHMPs tend to occur at any age but more at middle age later. It was reported by Guthire1 that rate of metastases at 5, 10, and 15years was 13%, 33%, and 64% respectively and rate of survival at 5, 10, and 15years was 65%, 45%, and 15%1
Initially, tumor excision was the chief treatment of choice for patients with IHMP and early operation mortality was reported from 9% to 24%. Hemorrage during operation was the main etiological reason of operation mortality. For the abundant blood flow in IHMP, it is very difficult for surgery to resect tumor completely. Though embolization therapy decrease hemorrhage during surgery, however embolization should not be used alone to treat IHMP. In addition IHMP is characteristic of high rate of recurrence and far metastases. So radiosurgery was necessary for IHMP even if after tumor resection.
It was reported7 that the mean interval of recurrence was 12 months later after tumor resection and rate of metastases at five years after tumor resection was 33%; metastases could happen in 2years to 20 years later after diagnosis and the mean interval of metastases ranged from 63 to 99 months. Recently it was reported 9 that rate of focal recurrence was 88% using surgery alone while it could be declined to 12.5% in combination with radiotherapy after surgery. However another scholar reported that there was no significant difference between patients with radiotherapy and patients without radiotherapy in recurrence and survival terms. Guthrie et al1 and Dufour et al9 recommend 50Gy irradiation dose to control local recurrence without side effects. Some persons recommended radiotherapy before surgery but how to get accurate diagnosis before surgery was a big problem. Since 1980s, with its good local tumor control, stererotactic radiosurgery has become a pivot role for the treatments of IHMPs. In 2002 Sheehan et al from the university of pittsburgh gamma system center reported that:11 of 14 patients had local tumor control ( 12 of 15 tumor lesions had obvious shrinkage);3 patients had local recurrence (mean 21 months, range 12- 75 months); under the mean period o follow-up 31.3 months, the rate of tumor control was 80%; The rate of tumor control and the rate of survival at 5 years was 76% and 100%, respectively; they recommended that diameter of a tumor should be no more than 3cm and peripheral prescription irradiation dose should be at least 15Gy.
Of 5 patients in our study, the rate of tumor control was 80%, accordant to reports from other gamma centers; from data in table1, the first patient had the same mass-resected effectiveness as conventional surgery using GKS and another 3 patients had pleasing local tumor control. All of these results indicated that GKS was an effective method for IHMPs and IHMPs was sensitive to gamma radiation. Of course, volume of tumor was still another important factor for GKS to achieve good outcome. Tumor of the recurrent patient with diameter >3cm3 was still intractable even if she had underwent GKS 4 times and craniotomy and resection one time. Her survival term was about 48 months. Her intervals of each recurrence were no more than 6 months, which was accordant to Sheehan抯 view about this point. In addition experiences from gamma centers all around world indicated that GKS could not prevent tendency of far metastases. Data from gamma centers were showed in table2.