Our results establish that WBRT + SRS produces leukoencephalopathy at a much higher rate than SRS alone. Surprisingly, an SRS integral dose of over only 3 J predicts for leukoencephalopathy in patients treated with SRS alone. Our data define a dosimetric threshold at which radiation-induced leukoencephalopathy is likely to occur following SRS. As the survival of patients with CNS metastases increases and as the neurotoxicity of chemotherapeutic and targeted agents becomes established, the threshold of 3 J may influence the therapeutic management of patients with multiple brain metastases.
(P055) Can High-Grade Prostate Cancer (Gleason 8–10) Be Cured With Definitive Local Therapy Without Testosterone Suppression? Five-Year Outcomes Employing Up-Front Prostatectomy in Patients With Clinically Localized, Nonmetastatic Disease
Patients with HGPC at diagnosis have high rates of early disease recurrence, though mortality at 5 years remains low. Following RP without systemic therapy, high primary GS and initial post-RP PSA were independently associated with worse FFF outcomes.
Overall, 40%-thresholded 18F-FDG PET contours nonsignificantly enlarge PTVs when multiphase free-breathing, inspiration, and expiration breath-hold scans are used for Vero SBRT. Whether 18F-FDG PET contours improve local control of moving lung tumors treated by Vero SBRT needs further study.
(P125) Glioblastoma Multiforme Outcome Comparison Between Pediatrics and Adults: Is There a Difference?
This is the first report to directly compare pediatric and adult patients with GBM. Pediatric patients had significantly superior OS and CSS when compared with adults, and these differences remained significant over time and on multivariate analysis. The underlying cause of these survival differences between pediatrics and adults requires exploration, with attention to molecular biological tumor differences.
(P140) Clinical Predictors of Survival for Patients With Stage IV Cancer Referred to Radiation Oncology
These data suggest that a model that considers performance status, extent of disease, serum albumin, mental status, and primary tumor site represents a clinically relevant tool in radiation oncology to predict survival for patients with stage IV cancer.
(P014) Absence of Infection From Injection of a Rectal Spacer Into the Anterior Perirectal Fat Space
With proper preparation and antibiotics, placement of the rectal spacer into the anterior perirectal fat is extremely safe, without any risk of infection, in our series. Also, infections were not found in patients who had rectal wall penetration with the rectal spacer applicator needle.
(P007) Pooled Analysis of Locoregional Relapse After Minimally Invasive Surgery Alone for Intermediate- or High-Risk HPV+ Oropharyngeal Squamous Cell Carcinoma
In the HPV+ population, ECE remains a significant risk factor for LRR without adjuvant therapy after MIS. Patients with intermediate-risk disease after MIS have moderate rates of LRR.
(P062) Comparison of Stereotactic Body Radiotherapy (SBRT) and Conventional External Beam Radiotherapy (EBRT) in Renal Cell Carcinoma (RCC)
The data support that SBRT improves local control over standard fractionation schemes. Higher dose per fraction, with a BED in the range of 48 Gy10, is a safe and effective local treatment modality for RCC.