Local control and overall survival for adjuvant stereotactic radiosurgery in patients with residual or recurrent disease

Prior studies of post-operative stereotactic radiosurgery (SRS) have not distinguished between Adjuvant SRS (ARS) versus Adjuvant SRS to residual/recurrent disease (ARD). In this study, we defined ARS and ARD and investigated local control (LC), overall survival (OS), distant development of brain metastases (DBF), and leptomeningeal disease (LMD). We retrospectively identified BM patients who received surgical resection and SRS for BM from an IRB approved database between Jan 2009-Aug 2015. Patients were stratified into two groups: ARS and ARD. LC was determined by follow-up MRI studies and OS was measured from the date of surgery. LC and OS were assessed using the Kaplan-Meier method. 70 cavities underwent surgical resection of BM and received SRS to the post-operative bed. 41 cavities were classified as ARS and 29 as ARD. There was no significant difference in 12-month LC between the ARS and ARD group (71.4 vs. 80.8%, respectively; p = 0.135) from the time point of SRS. The overall 1-year survival for ARS and ARD was 79.9 and 86.1%, respectively (p = 0.339). Mean time to progression was 6.45 and 8.0 months and median follow-up was 10 and 15 months for ARS and ARD, respectively. 11.8% of ARS patients and 15.4% of ARD patients developed LMD, p = 0.72. 29.4% of ARS and 48.0% of ARD patients developed DBF, p = 0.145. Our findings suggest that observation after surgical resection, with subsequent treatment with SRS after the development of local failure, may not compromise treatment efficacy. If validated, this would spare patients who do not recur post-surgically from additional treatment.

Tumor bed radiosurgery following resection of brain metastases: a review

There is a growing interest in adjuvant radiosurgery following resection of hematogenous brain metastases. We have identified 12 series reporting on a total of 480 patients treated to a tumor bed following microsurgery. These cases fall into 3 paradigms: adjuvant radiosurgery as an alternative to whole-brain radiotherapy (WBRT), radiosurgery as an intensification of adjuvant WBRT and adjuvant radiosurgery for patients having failed prior WBRT. For these paradigms the reported crude local control rates are 79%, 92% and 95%, respectively. The procedure appears well tolerate with approximately a 5% risk of late radiation necrosis. Prospective data is lagging behind clinical practice and plans for prospective trials are discussed.

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.