Relevance of gamma knife radiosurgery alone for the treatment of non-small cell lung cancer brain metastases

Cerebral metastases

Brain metastases are common and deadly. Over the last 25 years GKNS has been established as an invaluable treatment. It may be used as a primary treatment or after either surgery or WBRT. Patients are assessed using one of a number of available scales. GKNS may be repeated for new metastases and for unresponsive tumors. Prescription doses are usually between 18 and 20Gy. The use of advanced MR techniques to highlight sensitive structures like the hippocampi have extended the efficacy of the treatment. More recently GKNS has been used with different target therapies with improved results. More recently frameless treatments have become more popular in this group of very sick patients. GKNS controls tumors in between 80% and over 95% of cases and may even be used for brainstem tumors.

Tumor Control Probability of Radiosurgery and Fractionated Stereotactic Radiosurgery for Brain Metastases

PURPOSE

As part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy, tumor control probability (TCP) after stereotactic radiosurgery (SRS) and fractionated stereotactic radiosurgery (fSRS) for brain metastases was modeled based on pooled dosimetric and clinical data from published English-language literature.

METHODS AND MATERIALS

PubMed-indexed studies published between January 1995 and September 2017 were used to evaluate dosimetric and clinical predictors of TCP after SRS or fSRS for brain metastases. Eligible studies had ≥10 patients and included detailed dose-fractionation data with corresponding ≥1-year local control (LC) data, typically evaluated as a >20% increase in diameter of the targeted lesion using the pre-SRS diameter as a reference.

RESULTS

Of 2951 potentially eligible manuscripts, 56 included sufficient dose-volume data for analyses. Accepting that necrosis and pseudoprogression can complicate the assessment of LC, for tumors ≤20 mm, single-fraction doses of 18 and 24 Gy corresponded with >85% and 95% 1-year LC rates, respectively. For tumors 21 to 30 mm, an 18 Gy single-fraction dose was associated with 75% LC. For tumors 31 to 40 mm, a 15 Gy single-fraction dose yielded ∼69% LC. For 3- to 5-fraction fSRS using doses in the range of 27 to 35 Gy, 80% 1-year LC has been achieved for tumors of 21 to 40 mm in diameter.

CONCLUSIONS

TCP for SRS and fSRS are presented. For small lesions ≤20 mm, single doses of ≈18 Gy appear generally associated with excellent rates of LC; for melanoma, higher doses seem warranted. For larger lesions >20 mm, local control rates appear to be ≈ 70% to 75% with usual doses of 15 to 18 Gy, and in this setting, fSRS regimens should be considered. Greater consistency in reporting of dosimetric and LC data is needed to facilitate future pooled analyses. As systemic and biologic therapies evolve, updated analyses will be needed to further assess the necessity, efficacy, and toxicity of SRS and fSRS.

Stereotactic irradiation of non-small cell lung cancer brain metastases: evaluation of local and cerebral control in a large series

Stereotactic radiotherapy (SRT) of brain metastases (BM) results are often reported in the heterogeneous primitive population. Here, we report our experience in consecutively treated patients who underwent SRT alone for BM from non-small cell lung cancer (NSCLC). This retrospective analysis included consecutive patients with no history of cerebral treatment who underwent Cyberknife™ SRT for BM from NSCLC in our institution from 2007 to 2016. One hundred patients were included in the study, with a median follow-up of 33 months (20–64). Mean age was 63 years (SD ± 10); 88% had Karnofsky Performance Status (KPS) > 70; 67% had unique BM; 18 patients received single-fraction SRT (20–25 Gy), and 82 received hypo-fractionated SRT (HSRT) (24–36 Gy in 3–5 fractions). We reported a complication rate of 17% (2% of G3-4). Median survival was 10.1 months [95% confidence interval (CI) 7.8–13.9]. At 1 year, local and cerebral control rates were respectively 78.7% (95% CI 70–86.5%) and 43% (95% CI 33.5–53%). Thirty patients underwent salvage treatment (whole brain radiation therapy, n = 13; SRT, n = 14; surgery, n = 3). Cyberknife™-based SRT is an effective treatment associated with high local control rate with low morbidity for patients with NSCLC’s BM. Close follow-up is necessary to perform salvage treatment.

Cystic brain metastases had slower speed of tumor shrinkage but similar prognosis compared with solid tumors that underwent radiosurgery treatment

Purpose

Traditionally, radiosurgery was considered less effective for patients with cystic brain metastases. However, comparisons of prognosis between cystic and solid brain metastases in cancer patients have been seldom reported. We aimed to compare the survival between cystic and solid brain metastases and assess risk factors for overall survival after brain metastases (BMOS) in patients who underwent radiosurgery treatment.

Patients and methods

The Kaplan-Meier method and multivariate Cox regression analysis were used to compare survival time and evaluate risk factors for BMOS.

Results

A total of 356 patients (including 498 brain metastases) were analyzed in our study, including 67 patients (67/356, 18.8%) with 75 cystic brain metastases. There is no statistical significance in BMOS between patients with cystic (17 months, range: 3-64 months) and solid (17.5 months, range: 1-65 months) brain metastases (P=0.148). However, the volume of cystic brain metastases decreased more slowly than solid brain metastases (P<0.05). The results indicated that high recursive partitioning analysis classification (P=0.006), large volume of brain metastases (P=0.006), and different primary lesion (especially gastrointestinal tract tumor) (P=0.001) were associated with poor prognosis in patients with brain metastases.

Conclusion

There is no difference in prognosis and local control between patients with cystic and solid brain metastases who underwent radiosurgery. However, the rate and speed of tumor shrinkage were lower in cystic brain metastases after radiotherapy. Patients with larger brain metastases had shorter survival time, regardless of cystic or solid brain metastases.

Feasibility and safety of cavity-directed stereotactic radiosurgery for brain metastases at a high-volume medical center

Objective

Our objective was to report safety and efficacy of stereotactic radiosurgery (SRS) to the surgical bed following resection of brain metastases.

Methods

Eighty-seven consecutive patients who underwent cavity-directed SRS to the operative bed for the treatment of brain metastases between 2002 and 2010 were evaluated. SRS required a gadolinium-enhanced, high-resolution, T1-weighted magnetic resonance imaging for tumor targeting and delivered a median dose of 18 Gy (14-22 Gy) prescribed to encompass the entire resection cavity. Whole brain irradiation was reserved for salvage. Patients were followed every 3 months with clinical examination and magnetic resonance imaging. Overall survival, local and regional recurrence, and factors affecting these outcomes were evaluated using Kaplan-Meier and log-rank analyses.

Results

The median imaging follow-up was 7.1 months, with >40% of patients having imaging for ≥1 year. Local control at 1 and 2 years was 82% and 75%, respectively. Cavity recurrence was more common with a tumor diameter >3 cm (P < .020) or resection cavity volume >14 mL (P < .050). One-year local control for tumors <2 cm, 2 cm to 3 cm, and >3 cm were 100%, 86%, and 72%, respectively. Neither subtotal resection nor target margins >2 mm to 3 mm affected local control. The median overall survival was 14.3 months with actuarial 5-year survival of 20%. Actuarial regional central nervous system recurrence was 44% at 1 year. On univariate analysis, only the presence of extracranial disease was associated with survival (P < .001) and central nervous system failure (P < .030).

Conclusions

Excellent local control is achievable with cavity-directed SRS in well-selected patients, particularly for lesions with diameter <3 cm and resection cavity volumes <14 mL. Long-term survival is possible for select patients.