Stereotactic Radiosurgery in Brain Tumors: Impact of Timing of MRI Michael
1 Osei ,
Rebecca
1 Mirochnik ,
and Anuj
1,2 Goenka
1Donald
and Barbara Zucker School of Medicine at Hofstra/Northwell 2Department of Radiation Medicine at Long Island Jewish Medical Center
Introduction Patients with metastatic brain tumors may be treated with stereotactic radiosurgery (SRS) using a Gamma Knife (GK) platform or a linear accelerator (LINAC)-based platform. While the usual practice is to acquire an MRI on the day of GK treatment, there is greater heterogeneity in the timing of MRI for patients receiving LINACbased treatment. In the case of prostate cancer it has been found that there is a deleterious effect of underdosing in having an increased time 1 between planning and treatment.
Conclusions
Results Demographics Gender
Race
Ethnicity
Male
Female
22
23
White
Black
Asian
Other
28
7
3
7
Not Hispanic
Hispanic
40
5
Table 1: Demographic of people included in SPSS analysis of patients with brain metastasis treated with LINAC SRS
Hypothesis
Future Direction
The increased interval between MRI and SRS treatment on the LINAC will impair local tumor control.
Methods We reviewed our institutional database to identify all patients with brain metastases treated after 2016 using a LINAC platform for SRS. We recorded the date of MRI used for treatment planning and the date of SRS delivery. Clinical records and imaging were reviewed by a dedicated CNS radiation oncologist to assess local control. If whole brain radiation therapy was used as salvage treatment, the patient was censored at the date of that treatment. SPSS was utilized for statistical analysis.
Shorter intervals between brain MRI and SRS was assumed to be associated with improvement in local control. Our data did indicate this by showing that planning workflow in which the MRI is performed as close as possible to simulation and treatment using LINAC SRS for patients with brain metastases would decrease local recurrence. There being no significant difference between radionecrosis may indicate that timing if MRI does not impact this complication; however, these results may just be due to a small sample size.
Figure 1: Cox Regression Survival graph of lesion recurrence in patients beginning from time of treatment with SRS . The patients were separated based on the time between their planning MRI and SRS treatment date. The first group was treated within 25 days of the MRI plan and the second group was treated after 25 days. There was a significant decrease in lesion recurrence with the patients that were treated within 25 days (p<0.05).
Days 0-25 Days 25-40
Radionecrosis 4 2
Figure 7: Independent CRISPR knockout of CDK4 or CDK6 does not cause dropout in most breast cancer cell lines Table 2: Record of patients for radionecrosis studied.
No Radionecrosis 26 28
separated into two groups based on the time between their planning MRI and SRS treatment date. The first group was treated within 25 days of the MRI plan and the second group was treated after 25 days. There was no significant difference between the groups.
Future projects can standardize the patients compared based on the radiation dosage received and on if the treatment was given fractionated or unfractionated. Severity of their conditions upon initial treat can be considered as well. We will also compare clinical outcomes between patients treated with LINAC and GK. GK inherently has a shorter time period between planning and treatment so this may potentially be a factor if there is a greater local control in patients treated with GK.
Resources 1. Mannerberg, A., Persson, E., Jonsson, J., Gustafsson, C. J., Gunnlaugsson, A., Olsson, L. E., & Ceberg, S. (2020). Dosimetric effects of adaptive prostate cancer radiotherapy in an MR-linac workflow. Radiation Oncology, 15(1), 1-9.