Innovations in radiation treatment for cancer patients have taken another step forward as researchers compare two cutting-edge techniques for managing multiple brain metastases (MBM). A clinical study conducted at the Union Oncology Centre, Union Hospital, Hong Kong SAR, assessed the dosimetric and radiobiological outcomes of volumetric modulated arc therapy (VMAT) against dynamic conformal arc therapy (DCAT). This important research sheds light on how these techniques can optimize patient care by minimizing side effects and maximizing treatment efficacy.
The study recruited 11 patients with 33 brain lesions between November 2022 and April 2024, focusing on how each therapy's techniques impact treatment quality. When it came to the dose coverage for the gross tumor volume (GTV) and planning target volume (PTV), both VMAT and DCAT demonstrated their ability to meet oncologists’ prescriptions effectively. Notably, VMAT exhibited superior dose homogeneity, which is particularly beneficial for larger tumors, offering wider treatment margins with lower risks of excessive radiation exposure to healthy brain tissue.
Meanwhile, DCAT showed remarkable target conformity, especially for tumors smaller than 1 cc. "This is clinically significant, as ensuring precise targeting can prevent unnecessary damage to healthy brain tissue," noted the authors of the article. Patients participating in the study had varied tumor sizes, with the average individual PTV volume measuring 1.76 cc and the total PTV averaging 5.29 cc.
Among the cohort, six patients were female and five were male, aged between 38 and 68 years with a mean age of 63. The prescribed doses ranged from 18 to 24 Gy at the treatment percentage prescribed at the 80% isodose line, emphasizing the precision of these techniques. According to the findings, the median near-minimum dose (D98%) was greater for VMAT plans, at 21.10 Gy, which translates to 105% of the prescribed dose.
Despite these advantages, VMAT plans yielded lower near-maximum doses and doses to 50% of the target volume compared to DCAT. For example, maximum doses (D2%) were recorded at 123.09% for VMAT, versus 124.76% for DCAT. This nuanced detail merits consideration when determining the most appropriate treatment plan for individuals based on their distinct tumor characteristics.
Both VMAT and DCAT were shown to maintain low risks of complications associated with radiation-induced toxicity. Key metrics analyzed included V12Gy—indicating the volume of brain receiving 12 Gy or more radiation—which averaged 13.97 cc for VMAT and 13.82 cc for DCAT with no statistically significant differences noted. This demonstrates comparable efficacy when it is less about the treatment method and more about maintaining patient safety.
Normal tissue complication probability (NTCP) outcomes also hovered below the 5% threshold for both techniques, with VMAT producing 0.13% and DCAT slightly lower at 0.11%. Keeping these percentages low is encouraging as radiation-induced complications can significantly impair patients' quality of life. Both therapies support the goal of protecting neurocognitive function following treatment.
The researchers, led by Chen-jun Jiang and Harry Chi-yuen Cheng, maintain there are clinical implications for their findings. For small PTV volumes, it may be preferable to opt for DCAT, whereas VMAT could be the treatment of choice for larger tumors. The authors advocate adopting individualized treatment plans, aligning the choice of therapy with tumor characteristics to achieve the best possible outcomes for patients battling MBM.
Nevertheless, the study concluded with caution, noting the importance of anticipated advancements and the necessity for future studies to continue validating these findings across larger patient populations. The opportunity to explore the potential of dynamic therapy extensions alongside these approaches can offer improved solutions to this challenging treatment domain.
This study significantly contributes to the growing body of evidence supporting the use of advanced stereotactic radiosurgery techniques aimed at enhancing patient outcomes through precise delivery modalities. The clinical analysis not only aids oncologists and radiation therapists but also aims at refining strategies to uphold quality of life for patients undergoing treatment for brain metastases.
