Researchers from the department of radiation oncology at the VU University Medical Center in Amsterdam, the Netherlands, have proposed a novel formula for the optimization of radiosurgery dose for any given lesion volume in patients with brain metastasis.
Bain metastasis occurs when cancer cells from a primary tumor located somewhere in the body spread to the brain. The condition can be associated with a poor quality of life and treatment usually consists of supportive care strategies to try to control and slow growth of the disease.
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To help providers better construct care strategies unique to their patients’ circumstances and severity of disease, researchers led by Omar Bohoudi, VU University Medical Center, created a formula that arrives at a recommended radiosurgery dose based on lesional volume and brain toxicity parameters. Their data was published in Radiotherapy & Oncology.
The model was constructed using 30 historical linac-based dynamic conformal arc radiosurgery plans for single brain metastases with risk-adapted dose ranging from 15 Gy to 24 Gy. Developers also used a number of statistical methods to arrive at formula parameters, relationship of coefficients, and maximum Gy dose as a function of a given lesion.
The model was then validated on 65 new patients with 138 lesions, with 44 patients exhibiting multiple brain metastases: 25 with two lesions, eight with three lesions, five with four lesions, five with five lesions, and one with six lesions. All patients were subjected to non-coplanar volumetric modulated stereotactic arc treatment for planning target volume sizes ranging from 0.2 cc to 30.3 cc.
Ultimately, researchers noted a strong correlation between predicted dose and resulting dose in the 65 patients used to validate the model; however, they did also find some limitations. In particular, they said that their model for V12Gy in small lesions slightly overestimates the volume of brain tissue receiving a specific dose. Additionally, the location of the studied lesions were confined to the boundaries of the entire brain structure, which likely means that the model overestimates V12Gy in brain tissue for lesions with an extreme superficial location.
Still, they concluded that the proposed formula for brain metastasis could assist clinicians in determining individualized optimal dose prescriptions, making it easier for them to manage the disease and protect healthy regions of the brain.
