Stereotactic radiosurgery of the postoperative resection cavity for brain metastases

Stereotactic radiosurgery boost to the resection bed for oligometastatic brain disease: challenging the tradition of adjuvant whole-brain radiotherapy

Object

Whole-brain radiation therapy (WBRT) has been the traditional approach to minimize the risk of intracranial recurrence following resection of brain metastases, despite its potential for late neurotoxicity. In 2007, the authors demonstrated an equivalent local recurrence rate to WBRT by using stereotactic radiosurgery (SRS) to the operative bed, sparing 72% of their patients WBRT. They now update their initial experience with additional patients and more mature follow-up.

Methods

The authors performed a retrospective review of all cases involving patients with limited intracranial metastatic disease (≤ 4 lesions) treated at their institution with SRS to the operative bed following resection. No patient had prior cranial radiation and WBRT was used only for salvage.

Results

From November 2000 to June 2009, 52 patients with a median age of 61 years met inclusion criteria. A single metastasis was resected in each patient. Thirty-four of the patients each had 1 lesion, 13 had 2 lesions, 3 had 3 lesions, and 2 had 4 lesions. A median dose of 1500 cGy (range 800–1800 cGy) was delivered to the resection bed targeting a median volume of 3.85 cm3 (range 0.08–22 cm3). With a median follow-up of 13 months, the median survival was 15.0 months. Four patients (7.7%) had a local recurrence within the surgical site. Twenty-three patients (44%) ultimately developed distant brain recurrences at a median of 16 months postresection, and 16 (30.7%) received salvage WBRT (8 for diffuse disease [> 3 lesions], 4 for local recurrence, and 4 for diffuse progression following salvage SRS). The median time to WBRT administration postresection was 8.7 months (range 2–43 months). On univariate analysis, patient factors of a solitary tumor (19.0 vs 12 months, p = 0.02), a recursive partitioning analysis (RPA) Class I (21 vs 13 months, p = 0.03), and no extracranial disease on presentation (22 vs 13 months, p = 0.01) were significantly associated with longer survival. Cox multivariate analysis showed a significant association with longer survival for the patient factors of no extracranial disease on presentation (p = 0.01) and solitary intracranial metastasis (p = 0.02). Among patients with no extracranial disease, a solitary intracranial metastasis conferred significant additional survival advantage (43 vs 10.5 months, p = 0.05, log-rank test). No factor (age, RPA class, tumor size or histological type, disease burden, extent of resection, or SRS dose or volume) was related to the need for salvage WBRT.

Conclusions

Adjuvant SRS to the metastatic intracranial operative bed results in a local recurrence rate equivalent to adjuvant WBRT. In combination with SRS for unresected lesions and routine imaging surveillance, this approach achieves robust overall survival (median 15 months) while sparing 70% of the patients WBRT and its potential acute and chronic toxicity.

Control of brain metastases using frameless image-guided radiosurgery

Object

Radiosurgery is an important and well-accepted method in the management of brain metastases. Using conventional frame-based techniques, high lesional control rates are expected. The introduction of image-guided techniques allows for improved patient comfort and workflow. Some controversy exists as to the accuracy of imageguided techniques and consequently the impact they might have on control of brain metastases (as opposed to the level of control achieved with frame-based methods). The authors describe their initial 15-month experience with image-guided radiosurgery (IGRS) using Novalis with ExacTrac for management of brain metastases.

Methods

The authors reviewed the cases of brain metastasis treated by means of IGRS in their tertiary regional radiation oncology service over a 15-month period. During the study period 54 patients (median age 57.9 years) harboring 108 metastases were treated with IGRS. The median time from cancer diagnosis to development of brain metastasis was 12 months (range 0–144 months). The median tumor volume was 0.98 cm3 (range 0.03–19.07 cm3). The median prescribed dose was 18 Gy to the 80% isodose line (range 14–20 Gy). Lesions were followed with postradiosurgery MR imaging every 2–3 months following treatment.

Results

The median follow-up period was 9 months (range 0–20 months). Median actuarial survival was 8.6 months following IGRS. Eight patients with 18 lesions died within the first 2 months after the procedure, before scheduled follow-up imaging. Thus 90 lesions (in 46 patients) were followed up with imaging studies. Lesions that were unchanged or reduced in size were considered to be under control. The 6-month actuarial lesion control rate was 88%. Smaller lesions (< 1 cm3) had a statistically improved likelihood of complete imaging response (loss of all contrast-enhancement p = 0.01).

Conclusions

Image-guided radiosurgical treatment of brain metastases resulted in high rates of tumor control comparable to control rates reported for frame-based methods. High control rates were seen for small lesions in which spatial precision in dose delivery is critical. These data suggests that in regard to lesion control, IGRS using Novalis with ExacTrac is equivalent to frame-based radiosurgery methods.

Adjuvant Gamma Knife radiosurgery following surgical resection of brain metastases: a 9-year retrospective cohort study

Given the potential morbidity of whole brain radiation therapy (WBRT), there has been an increasing trend to defer WBRT and deliver Gamma Knife stereotactic radiosurgery (GKS) to cerebral metastatic lesions. We analyzed our experience delivering GKS to the tumor cavity following surgical resection of brain metastases and compared our results to patients receiving WBRT after surgical resection of a metastatic lesion. We performed a retrospective review of patients undergoing surgical resection of at least one brain metastasis between December 1999 and December 2008. Both univariate and multivariate Cox proportional hazards regression were utilized to analyze the influence of various prognostic factors on survival. Twenty-five patients had a metastatic lesion resected followed by adjuvant GKS to the resection cavity while another 18 had surgical resection followed by WBRT. Aside from a disparity in gender distribution (72% of GKS patients were female while women only constituted 28% of the WBRT group), no significant differences existed between groups. The median survival for patients receiving GKS was 15.00 months as compared to 6.81 months among those receiving WBRT (P = 0.08). Univariate Cox regression analysis identified the number of metastases (HR 1.65, 95% CI 1.07-2.54, P = 0.02) and regional recurrence (RR 5.23, 95% CI 1.78-15.38, P = 0.003) as poor prognostic factors. Multivariate regression analysis showed that regional recurrence (HR 5.17, 95% CI 1.69-15.78, P = 0.004) was again strongly associated with worse survival. Although limited by the retrospective nature of our study and lack of some clinical measures, patients undergoing GKS to the resection cavity had a trend towards longer median survival.

Gamma Knife radiosurgery to the surgical cavity following resection of brain metastases

OBJECT

This study evaluated the efficacy of postoperative Gamma Knife surgery (GKS) to the tumor cavity following gross-total resection of a brain metastasis.

METHODS

A retrospective review was conducted of 700 patients who were treated for brain metastases using GKS. Forty-seven patients with pathologically confirmed metastatic disease underwent GKS to the postoperative resection cavity following gross-total resection of the tumor. Patients who underwent subtotal resection or who had visible tumor in the resection cavity on the postresection neuroimaging study (either CT or MR imaging with and without contrast administration) were excluded. Radiographic and clinical follow-up was assessed using clinic visits and MR imaging. The radiographic end point was defined as tumor growth control (no tumor growth regarding the resection cavity, and stable or decreasing tumor size for the other metastatic targets). Clinical end points were defined as functional status (assessed prospectively using the Karnofsky Performance Scale) and survival. Primary tumor pathology was consistent with lung cancer in 19 cases (40%), melanoma in 10 cases (21%), renal cell carcinoma in 7 cases (15%), breast cancer in 7 cases (15%), and gastrointestinal malignancies in 4 cases (9%). The mean duration between resection and radiosurgery was 15 days (range 2-115 days). The mean volume of the treated cavity was 10.5 cm3 (range 1.75-35.45 cm3), and the mean dose to the cavity margin was 19 Gy. In addition to the resection cavity, 34 patients (72%) underwent GKS for 116 synchronous metastases observed at the time of the initial radiosurgery.

RESULTS

The mean radiographic follow-up duration was 14 months (median 10 months, range 4-37 months). Local tumor control at the site of the surgical cavity was achieved in 44 patients (94%), and tumor recurrence at the surgical site was statistically related to the volume of the surgical cavity (p=0.04). During follow-up, 34 patients (72%) underwent additional radiosurgery for 140 new (metachronous) metastases. At the most recent follow-up evaluation, 11 patients (23%) were alive, whereas 36 patients had died (mean duration until death 12 months, median 10 months). Patients who showed good systemic control of their primary tumor tended to have longer survival durations than those who did not (p=0.004). At the last clinical follow-up evaluation, the mean Karnofsky Performance Scale score for the overall group was 78 (median 80, range 40-100).

CONCLUSION

Radiosurgery appears to be effective in terms of providing local tumor control at the resection cavity following resection of a brain metastasis, and in the treatment of synchronous and metachronous tumors. These data suggest that radiosurgery can be used to prevent recurrence following gross-total resection of a brain metastasis.

Advances in technology for intracranial stereotactic radiosurgery

Stereotactic radiosurgery (SRS) refers to a single radiation treatment delivering a high dose to an intra-cranial target localized in three-dimensions by CT and/or MRI imaging. Traditionally, immobilization of the patient's head has been achieved using a rigid stereotactic head frame as the key step in allowing for accurate dose delivery. SRS has been delivered by both Cobalt-60 (Gamma Knife) and linear accelerator (linac) technologies for many decades. The focus of this review is to highlight recent advances and major innovations in SRS technologies relevant to clinical practice and developments allowing for non-invasive frame SRS.

Brain metastases: current management and new developments

PURPOSE OF REVIEW

To review the state-of-the-art and new developments in the management of patients with brain metastases.

RECENT FINDINGS

Treatment decisions are based on prognostic factors to maximize neurologic function and survival, while avoiding unnecessary therapies. Whole-brain radiotherapy (WBRT) is the treatment of choice for patients with unfavorable prognostic factors. Stereotactic radiosurgery (SRS) or surgery is indicated for patients with favorable prognostic factors and limited brain disease. In single brain metastasis, the addition of either stereotactic radiosurgery or surgery to WBRT improves survival. The omission of WBRT after surgery or radiosurgery results in a worse local and distant control, though it does not affect survival. The incidence of neurocognitive deficits in long-term survivors after WBRT remains to be defined. New approaches to avoid cognitive deficits following WBRT are being investigated. The role of chemotherapy is limited. Molecularly targeted therapies are increasingly employed. Prophylaxis with WBRT is the standard in small-cell lung cancer.

SUMMARY

Many questions need future trials: the usefulness of new radiosensitizers; the role of local treatments after surgery; and the impact of molecularly targeted therapies on subgroups of patients with specific molecular profiles. Quality of life and cognitive functions are recognized as major endpoints in clinical trials.

Whole-brain radiotherapy and tumor bed radiosurgery following resection of solitary brain metastases

A standard approach to solitary brain metastases is resection followed by whole-brain radiation therapy (WBRT). Despite WBRT, the tumor bed remains a common site of failure. We reviewed outcomes following adjuvant WBRT with tumor bed radiosurgery (SRS). We retrospectively identified patients having undergone neurosurgical resection of a single brain metastasis followed by adjuvant WBRT and tumor bed SRS. SRS dose selection was independent of target volume (10 Gy peripheral dose). Outcomes were calculated actuarially. Patients were censured for local control at the time of last imaging. From 2005 to 2008, 27 patients were treated with WBRT and tumor bed SRS. Median age was 58.7 years, median KPS 80%. The primary malignancy was non-small cell lung cancer in 70%. Median follow-up was 9.7 months. Following the combination of surgery, WBRT and SRS the median overall survival was 17.6 months. Actuarial 2-year local control was 94%. The SRS boost was well tolerated with one patient (4%) requiring reoperation for symptomatic radiation necrosis 16 months post treatment. Radiosurgery can be safely added to WBRT as an adjuvant treatment following resection of a single brain metastasis. In our retrospective series, this combination treatment produced a high rate of local control.

Treatment of malignant tumors of the skull base with multi-session radiosurgery

OBJECTIVE

Malignant tumors that involve the skull base pose significant challenges to the clinician because of the proximity of critical neurovascular structures and limited effectiveness of surgical resection without major morbidity. The purpose of this study was to evaluate the efficacy and safety of multi-session radiosurgery in patients with malignancies of the skull base.

METHODS

Clinical and radiographic data for 37 patients treated with image-guided, multi-session radiosurgery between January 2002 and December 2007 were reviewed retrospectively. Lesions were classified according to involvement with the bones of the base of the skull and proximity to the cranial nerves.

RESULTS

Our cohort consisted of 37 patients. Six patients with follow-up periods less than four weeks were eliminated from statistical consideration, thus leaving the data from 31 patients to be analyzed. The median follow-up was 37 weeks. Ten patients (32%) were alive at the end of the follow-up period. At last follow-up, or the time of death from systemic disease, tumor regression or stable local disease was observed in 23 lesions, representing an overall tumor control rate of 74%. For the remainder of lesions, the median time to progression was 24 weeks. The median progression-free survival was 230 weeks. The median overall survival was 39 weeks. In the absence of tumor progression, there were no cranial nerve, brainstem or vascular complications referable specifically to CyberKnife radiosurgery.

CONCLUSION

Our experience suggests that multi-session radiosurgery for the treatment of malignant skull base tumors is comparable to other radiosurgical techniques in progression-free survival, local tumor control, and adverse effects.