Multidirectional Radio Surgery Treats Brain Cancer

A new study claims that stereotactic radiosurgery (SRS) is the preferred method of treating cancer patients with brain metastases.

Researchers at the University of Texas MD Anderson Cancer Center (Houston, TX, USA) randomly assigned 58 patients with one to three newly diagnosed brain metastases to SRS plus whole brain radiation therapy (WBRT) or SRS alone from Jan 2, 2001, to Sept 14, 2007. The patients were stratified by recursive partitioning analysis class, number of brain metastases, and radioresistant histology. The randomization sequence was masked until assignation, at which point both clinicians and patients were made aware of the treatment allocation. The primary endpoint was neurocognitive function, objectively measured as a significant deterioration (5-point drop compared with baseline) in the Hopkins Verbal Learning Test-Revised (HVLT-R) total recall at 4 months.

The researchers reported that the trial was stopped by the data monitoring committee--according to early stopping rules--on the basis that there was a high probability (96%) that patients randomly assigned to receive SRS plus WBRT were significantly more likely to show a decline in learning and memory function at 4 months than patients assigned to receive SRS alone. At four months, there were four deaths (13%) in the group that received SRS alone, and eight deaths (29%) in the group that received SRS plus WBRT. On the other hand, 73% of patients in the SRS plus WBRT group were free from CNS recurrence at one year, compared with 27% of patients who received SRS alone. In the SRS plus WBRT group, one case of grade 3 toxicity was attributed to radiation treatment; in the group that received SRS, one case of grade 3 toxicity (aphasia) was attributed to radiation treatment; two cases of grade 4 toxicity in the group that received SRS alone were diagnosed as radiation necrosis. The study was published in the October 5, 2009, online edition of the Lancet Oncology.

"Despite this difference in recurrence rates, we would still advise against WBRT because the risks of learning dysfunction outweigh the benefits of freedom from progression,” said lead author Eric L. Chang, M.D., an associate professor in the department of radiation oncology. "With close monitoring, salvage resections or additional radiation can be performed as necessary and patients who receive SRS alone will fare better with their quality of life intact.”

Stereotactic surgery is a minimally invasive form of surgical intervention, which makes use of a three-dimensional (3D) coordinates system to locate small targets inside the body and to perform a surgical procedure on them. Guide bars in the x, y, and z directions (or alternatively, in polar coordinates) are fitted with high precision vernier scales that allow the neurosurgeon to position the point of a probe inside the brain through a small trephine hole in the skull at the calculated coordinates for the desired structure.

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University of Texas MD Anderson Cancer Center