Low-dose radiosurgery for benign intracranial lesions

Robotic Stereotactic Radiotherapy for Intracranial Meningiomas-An Opportunity for Radiation Dose De-Escalation

OBJECTIVE

To evaluate the possibility of dose de-escalation, with consideration of the efficacy and safety of robotic stereotactic CyberKnife radiotherapy in patients diagnosed with intracranial meningiomas.

METHODS

The study group consisted of 172 patients (42 men and 130 women) treated in III Radiotherapy and Chemotherapy Clinic of Maria Sklodowska-Curie National Research Institute of Oncology in Gliwice between January 2011 and July 2018. The qualification for dose de-escalation was based on MRI (magnetic resonance imaging) features: largest tumor diameter less than 5 cm, well-defined tumor margins, no edema, and no brain infiltration. The age of patients was 21-79 years (median 59 years) at diagnosis and 24-80 years (median 62 years) at radiotherapy. Sixty-seven patients (Group A) were irradiated after initial surgery. Histopathological findings were meningioma grade WHO 1 in 51 and WHO 2 in 16 cases. Group B (105 patients) had no prior surgery and the diagnosis was based on the typical features of meningioma on MRI. All patients qualified for the robotic stereotactic CyberKnife radiotherapy, and the total dose received was 18 Gy in three fractions to reference isodose 78-92%.

RESULTS

Follow-up period was 18 to 124 months (median 67.5 months). Five- and eight-year progression free survival was 90.3% and 89.4%, respectively. Two patients died during the follow-up period. Progression of tumor after radiotherapy was registered in 16 cases. Four patients required surgery due to progressive disease, and three of them were progression free during further follow-up. Twelve patients received a second course of robotic radiotherapy, 11 of them had stable disease, and one patient showed further tumor growth but died of heart failure. Crude progression free survival after both primary and secondary treatment was 98.8%. Radiotherapy was well-tolerated: acute toxicity grade 1/2 (EORTC-RTOG scale) was seen in 10.5% of patients. We did not observe any late effects of radiotherapy.

CONCLUSION

Stereotactic CyberKnife radiotherapy with total dose of 18 Gy delivered in three fractions showed comparable efficacy to treatment schedules with higher doses. This could support the idea of dose de-escalation in the treatment of intracranial meningiomas.

A Pathophysiological Approach to Reduce Peritumoral Edema with Gamma Knife Radiosurgery for Large Incidental Meningiomas

Background: Peritumoral edema may be a prohibitive side effect in treating large incidental meningiomas with stereotactic radiosurgery. An approach that limits peritumoral edema and achieves tumor control with SRS would be an attractive management option for large incidental meningiomas. Methods: This is a retrospective cohort study of patients with large incidental meningiomas (≥2 mL in volume and/or 2 cm in diameter) treated with gamma knife radiosurgery (GKRS) between 2000 and 2019 in Taiwan and followed up for 5 years. The outcomes of a pathophysiological approach targeting the dural feeding artery site with a higher marginal dose (18–20 Gy) to enhance vascular damage and the parenchymal margin of the tumor with a lower dose (9–11 Gy) to reduce parenchymal damage were compared with those of a conventional approach targeting the tumor center with a higher dose and tumor margin with a lower dose (12–14 Gy). Results: A total of 53 incidental meningiomas were identified, of which 23 (43.4%) were treated with a pathophysiological approach (4 cases underwent a two-stage approach) and 30 (56.7%) were treated with a conventional approach. During a median follow-up of 3.5 (range 1–5) years, tumor control was achieved in 19 (100%) incidental meningiomas that underwent a single-stage pathophysiological approach compared with 29 (96.7%) incidental meningiomas that underwent a conventional approach (log-rank test: p = 0.426). Peritumoral edema developed in zero (0%) incidental meningiomas that underwent a single stage pathophysiological approach compared to seven (23.3%) incidental meningiomas that underwent a conventional approach (log-rank test: p = 0.023). Conclusions: Treatment of large incidental meningiomas with a pathophysiological approach with GKRS achieves similar rates of tumor control and reduces the risk of peritumoral edema. GKRS with a pathophysiological approach may be a reasonable management strategy for large incidental meningiomas.

Linear Accelerator-Based Radiosurgery of Grade I Intracranial Meningiomas

Objective

To determine the local control rate and complication rate in the treatment of grade I intracranial meningiomas.

Methods

A retrospective study was performed of patients with grade I meningioma who received radiosurgery with a dedicated linear accelerator from January 2002 to August 2012 with a minimum follow-up of 2 years. We performed descriptive statistics, logistic regression, and progression-free survival analysis through a Kaplan-Meier curve.

Results

Seventy-five patients with 78 grade I meningiomas received radiosurgery, 39 underwent surgery plus adjuvant radiosurgery, and 36 only radiosurgery. The follow-up median time was 68 months (range, 35–120 months). The tumor control rate was 93%, the 5-year progression-free survival was 92% (95% confidence interval, 77%–98%). Acute toxicity was 2.6%, and grade 1–2 late toxicity was 26.6%. Postradiosurgery edema was the main late morbidity. Age >55 years was the only significant factor for attaining a response >75%. The background of surgery before radiosurgery was the only significant prognostic factor for showing edema (odds ratio 5.78 [95% confidence interval, 2.14–15.64]).

Conclusions

The local control rate attained in our series is similar to that reported in other series worldwide; the acute toxicity rate was low and late toxicity was moderate.

Radiotherapy for Brain Metastases From Renal Cell Carcinoma in the Targeted Therapy Era: The University of Rochester Experience

OBJECTIVES

Radiotherapy remains the standard approach for brain metastases from renal cell carcinoma (RCC). Kinase inhibitors (KI) have become standard of care for metastatic RCC. They also increase the radiosensitivity of various tumor types in preclinical models. Data are lacking regarding the effect of KIs among RCC patients undergoing radiotherapy for brain metastases. We report our experience of radiotherapy for brain metastatic RCC in the era of targeted therapy and analyzed effects of concurrent KI therapy.

METHODS

We retrospectively analyzed 25 consecutive patients who received radiotherapy for brain metastases from RCC with whole-brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), or both. Kaplan-Meier rates of overall survival (OS) and brain progression-free survival (BPFS) were calculated and univariate analyses performed.

RESULTS

Lower diagnosis-specific graded prognostic assessment (DS-GPA) score and multiple intracranial metastases were associated with decreased OS and BPFS on univariate analysis; DS-GPA is also a prognostic factor on multivariate analysis. There was no significant difference in OS or BPFS for SRS compared with WBRT or WBRT and SRS combined. The concurrent use of KI was not associated with any change in OS or BPFS.

CONCLUSIONS

This hypothesis-generating analysis suggests among patients with brain metastatic RCC treated with the most current therapies, those selected to undergo SRS did not experience significantly different survival or control outcomes than those selected to undergo WBRT. From our experience to date, limited in patient numbers, there seems to be neither harm nor benefit in using concurrent KI therapy during radiotherapy. Given that most patients progress systemically, we would recommend considering KI use during brain radiotherapy in these patients.

Repeat courses of SRS in patients initially treated with SRS alone for brain-metastatic melanoma

Aim

Stereotactic radiosurgery (SRS) is often used in the treatment of brain metastatic melanoma. Little data exist regarding outcomes of repeat course of SRS in this population. We aimed to identify treatment outcomes and toxicities in melanoma patients treated with repeat SRS after upfront SRS.

Patients & methods

We reviewed ten consecutive patients treated with repeat SRS following upfront SRS alone for brain metastatic melanoma.

Results

The median overall survival from initial treatment was 17.5 months. The median overall survival from repeat SRS was 6.7 months with a 6-month local control rate of 80%. The majority of patients progressed systemically before death. Four patients reported six adverse events, all grade 1.

Conclusion

Prospective study regarding the safety and efficacy of repeat courses of SRS in patients with brain-metastatic melanoma, especially in combination with novel immunotherapies, is warranted.

Brain metastasis from melanoma: the prognostic value of varying sites of extracranial disease

Patients with brain metastasis from melanoma have poor outcomes. Radiation is used both for prognostic and symptomatic value. We aimed to further clarify the role of stereotactic radiosurgery (SRS) and whole brain radiotherapy (WBRT) as well as the prognostic implication of various sites of extracranial disease. The records of 73 consecutive patients treated at the University of Rochester Medical Center for brain-metastatic melanoma from January 2004 to October 2013 were reviewed. The median overall survival (OS) was 3.0 months. Patients treated with WBRT alone had decreased OS compared to those treated with SRS alone (HR = 0.38, p = 0.001) or WBRT and SRS (HR = 0.51, p = 0.039). The mean number of brain metastasis differed (p = 0.002) in patients in patients who received WBRT (4.0) compared to those who did not (2.0). Among patients with extracranial disease (n = 63), bone metastasis (HR = 1.86, p = 0.047, n = 15) was a negative prognostic factor; liver (HR = 1.59, p = 0.113, n = 17), lung (HR = 1.51, p = 0.23, n = 51) and adrenal metastasis (HR = 1.70, p = 0.15, n = 10) were not. In patients with concurrent brain and lung metastasis, those with disease limited to those two sites (OS = 8.7 mo, n = 13) had improved OS (HR = 0.44, p = 0.014) compared to those with additional disease (OS = 1.8 mo, n = 50). Based on this hypothesis-generating retrospective analysis, SRS may offer survival benefit compared to WBRT alone in patients with brain metastatic melanoma. Bone metastasis appears to confer a particularly poor prognosis. Those with disease confined to the lung and brain may represent a population with improved prognosis.

Analysis of patients with oligometastases undergoing two or more curative-intent stereotactic radiotherapy courses

PURPOSE

A subset of patients treated with curative-intent stereotactic radiotherapy (RT) for limited metastases (defined as five lesions or fewer) develop local failure and/or a small number of new lesions. We hypothesized that these patients would remain amenable to curative-intent treatment with additional RT courses.

METHODS AND MATERIALS

Of 121 prospective patients with five lesions or fewer treated with stereotactic RT, 32 underwent additional RT courses for local failure (n = 9) and/or new lesions (n = 29). Ten patients underwent three or more courses of RT.

RESULTS

The treated local failures developed a median of 20 months after RT completion. For the new oligometastases, the interval between the first and second RT course was 1-71 months (median, 8). Of the 32 patients undergoing multiple courses of curative-intent RT, the 2-year overall survival and progression-free survival rate was 65% and 54%, respectively. The corresponding 4-year rates were 33% and 28%. Compared with the 89 patients who underwent one RT course, these patients experienced a trend toward improved overall survival (median, 32 vs. 21 months, p = 0.13) and significantly greater progression-free survival (median, 28 vs. 9 months, p = 0.008).

CONCLUSION

The results of our study have shown that patients fare well with respect to survival and disease control with aggressive RT for limited metastases, even after local failure and/or the development of new metastases. Although patients amenable to multiple courses of curative-intent RT are arguably selected for more indolent disease, our hypothesis-generating analysis supports the notion of aggressively treating limited metastases, which, in some patients, might be curable and/or represent a chronic disease state.