Trends in Stereotactic Laser Ablation for Brain Tumors: Mounting Experience and Enhanced Technology Are Boosting Outcomes

Outcomes and operative times associated with stereotactic laser ablation for treating brain tumors dramatically improved over the past eight years at a single institution even as the procedure was increasingly used to treat metastases and radiation necrosis from radiosurgery failure. These findings — from a retrospective review of 240 Cleveland Clinic patients since 2011 — were detailed in a platform presentation this week at the 2019 annual scientific meeting of the American Association of Neurological Surgeons.

“Cleveland Clinic was one of the early adopters of stereotactic laser ablation treatment for brain tumors, so we have good data starting in 2011, when the technology became commercially available after FDA approval,” says the study’s principal investigator, Alireza M. Mohammadi, MD, a neurosurgeon with Cleveland Clinic’s Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center. “Assessing our experience allows us to detect important trends and develop evidence-based best practices for other centers with more limited experience to follow.”

Study design and findings

The study categorized patients into two time periods for comparison: the early period, from 2011 to 2014 (including 102 patients), and the more recent period, from 2015 to 2018 (138 patients). Extensive data on patient demographics, surgical and tumor characteristics, and temporary and permanent complications (the latter defined as unresolved after 6 months) were assessed.

The following differences were detected between the early and recent periods:

• Tumor types changed. In the early years, stereotactic laser ablation was predominantly used for upfront and recurrent gliomas (76.6%). Over time, utilization markedly increased for treating metastases and radiation necrosis following radiosurgery failure, changing from 25 combined cases (23.4%) in the early years to 58 cases (42.6%) in recent years.
• Operative time shortened, from 6.25 hours in the early years to 3.6 hours in recent years.
• Complication rates improved. Rates of permanent postoperative deficits declined from 15% to 4%, a significant change. Dr. Mohammadi says this decline was likely due in part to modification of the team’s surgical techniques, following review of the initial series of cases, to protect eloquent brain area close to the tumor and laser field (Neurosurg Focus. 2016;41:E11). “Additionally, there were no cases of infection or large hemorrhage needing surgery in the second cohort,” he notes.
• Postoperative mortality and severe morbidity decreased. Mortality improved from 4.2% in the early group to 1.5% in the recent period.

Dr. Mohammadi credits these substantial changes over the years to growing experience on the part of the multidisciplinary team as well as evolving technology. In 2013, a new generation of the state-of-the-art stereotactic laser ablation device (NeuroBlate® System) became available, allowing more efficient delivery of energy from the laser probe as well as improved planning and placement of the laser probe into the tumor.

Most common applications

Stereotactic laser ablation is a powerful tool that plays an increasing role in treating challenging brain tumors and their complications, Dr. Mohammadi notes. Some of the most important evolving applications include:

• Radiation necrosis. Radiation necrosis is a frequent complication of radiosurgery for brain metastases, occurring in about 10% to 15% of cases, often causing neurological deterioration. A multicenter study led by Cleveland Clinic (J Neurosurg. 2018;130:804-811) found that stereotactic laser ablation offers good control for radiation necrosis, resulting in stabilized performance and preserved quality of life and cognition.
• High-grade gliomas. Complete resection of difficult-to-access high-grade gliomas is rarely achievable surgically, according to Dr. Mohammadi, who served as lead author on a multicenter study assessing the role of stereotactic laser ablation for these tumors (Cancer Med. 2014;3:971-979 and Neurosurgery. 2018 Nov 23 [Epub ahead of print]). Laser ablation was shown to be safe and effective in this setting.

“We now have enough evidence to confidently say that stereotactic laser ablation can fill important roles for treating primary and metastatic brain tumors and radiation necrosis,” says Dr. Mohammadi. “We expect its uses to continue to evolve as technology advances, further enhancing our capabilities.”