People diagnosed with glioblastoma face one of the hardest forms of cancer to treat.
This fast-growing brain cancer can spread through nearby brain tissue, making it difficult for surgeons to remove every cancer cell without harming healthy areas that control speech, movement, memory and other important abilities.
For many patients, treatment begins with open brain surgery to remove as much of the tumor as possible. Surgery is usually followed by radiation and chemotherapy, but glioblastoma often returns even after aggressive treatment.
Doctors have increasingly used a less invasive option called laser interstitial thermal therapy, or LITT, for tumors that return, lie deep in the brain or cannot safely be removed through ordinary surgery. Instead of opening a large part of the skull, surgeons make a very small opening and guide a thin laser probe into the tumor.
Real-time MRI images help the medical team position the probe while avoiding important healthy brain tissue. Once it reaches the tumor, heat from the laser destroys cancer cells around the tip of the probe.
A new analysis from Washington University School of Medicine in St. Louis suggests that doctors may be able to improve the results of this treatment by paying close attention to two factors: how much tumor is destroyed and how early certain tumors are treated. The research was published in the Journal of Clinical Oncology.
The analysis included 787 people with different types of brain tumors who underwent laser treatment at 25 medical centers across the United States. Patients were followed for as long as five years, making this one of the largest collections of information on people treated with this approach.
The researchers found that the amount of tumor destroyed by the laser mattered greatly for people with newly diagnosed glioblastoma. Patients whose treatment destroyed at least 91% of their tumor survived for a median of about 2.1 years from diagnosis.
That result attracted attention because typical survival after standard treatment for glioblastoma is often around 12 to 18 months, although survival varies greatly between patients. The researchers say the finding could help doctors consider whether laser treatment might sometimes be useful earlier rather than reserving it mainly for tumors that have returned or cannot be removed with open surgery.
The study also produced an important finding for people whose cancer began somewhere else in the body and later spread to the brain. These secondary brain tumors are called brain metastases and are common in cancers such as lung, breast and melanoma.
For patients who had already received radiation, the researchers found better outcomes when laser treatment was performed while the brain tumor was still relatively small. This raises questions about the common practice of waiting through several scans to make sure a suspicious area is truly growing before treating it.
Waiting can sometimes prevent unnecessary procedures, because changes seen on brain scans after radiation are not always active cancer. But the new results suggest that when doctors are confident a tumor needs treatment, acting while it is smaller may provide an advantage.
The study also examined what recovery was like after the procedure. Unlike traditional brain surgery, which may require a larger opening in the skull and a longer recovery, laser treatment uses an incision only a few millimeters wide.
Patients in the study stayed in hospital for an average of about 32 hours. Most avoided intensive care, and the researchers reported that patients generally maintained their ability to carry out everyday activities after treatment.
Lead researcher Dr. Eric C. Leuthardt said the goal is not only to help patients live longer but also to preserve their quality of life. For someone facing a cancer with limited treatment options, being able to return home quickly after a procedure can be particularly meaningful.
The NeuroBlate system used for the procedure was developed by Monteris Medical and received U.S. Food and Drug Administration clearance in 2009. Washington University and Barnes-Jewish Hospital have been involved in the development and use of laser brain surgery for many years.
The results are encouraging, but they should not be interpreted as proof that laser therapy is better than standard open surgery for every patient. This analysis followed people receiving LITT and identified features linked with better outcomes; it was not a randomized trial directly assigning similar patients to laser treatment or open surgery.
Patients selected for different procedures can vary in tumor size, location, overall health and many other ways that influence survival. The 2.1-year survival result for patients with at least 91% tumor destruction therefore cannot by itself prove that LITT adds several months of life compared with standard surgery.
Still, the study offers practical information that doctors can use now. It suggests that if laser treatment is chosen, destroying as much of the tumor as safely possible and treating appropriate brain metastases before they become large may improve the chance of a better outcome.
The biggest value of the research may be that it helps turn an established technology into a more carefully targeted treatment strategy. Future controlled studies will be needed to determine exactly which patients benefit most, whether earlier laser treatment truly improves survival, and how it should be combined with radiation, chemotherapy and newer cancer treatments.
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Source: Washington University School of Medicine in St. Louis.
