Safety of stereotactic body radiation therapy for localized prostate cancer without treatment planning MRI.

The use of treatment planning prostate MRI for Stereotactic Body Radiation Therapy (SBRT) is largely a standard, yet not all patients can receive MRI for a variety of clinical reasons. Thus, we aim to investigate the safety of patients who received CT alone based SBRT planning for the definitive treatment of localized prostate cancer.

Our study analyzed 3410 patients with localized prostate cancer who were treated with SBRT at a single academic institution between 2006 and 2020. Acute and late toxicity was evaluated using the Common Terminology Criteria for Adverse Events version 5.0. Expanded Prostate Cancer Index Composite (EPIC) questionnaires evaluated QOL and PSA nadir was evaluated to detect biochemical failures.

A total of 162 patients (4.75%) received CT alone for treatment planning. The CT alone group was older relative to the MRI group (69.9 vs 67.2, p < 0.001) and had higher risk and grade disease (p < 0.001). Additionally, the CT group exhibited a trend in larger CTVs (82.56 cc vs 76.90 cc; p = 0.055), lower total radiation doses (p = 0.048), and more frequent pelvic nodal radiation versus the MRI group (p < 0.001). There were only two reported cases of Grade 3 + toxicity within the CT alone group. Quality of life data within the CT alone group revealed declines in urinary and bowel scores at one month with return to baseline at subsequent follow up. Early biochemical failure data at median time of 2.3 years revealed five failures by Phoenix definition.

While clinical differences existed between the MRI and CT alone group, we observed tolerable toxicity profiles in the CT alone cohort, which was further supported by EPIC questionnaire data. The overall clinical outcomes appear comparable in patients unable to receive MRI for their SBRT treatment plan with early clinical follow up.

Radiation oncology (London, England). 2022 Apr 02*** epublish ***

Katherine Amarell, Anna Jaysing, Christopher Mendez, Jonathan A Haas, Seth R Blacksburg, Aaron E Katz, Astrid Sanchez, Angela Tong, Todd Carpenter, Matthew Witten, Sean P Collins, Jonathan W Lischalk

Department of Radiation Medicine, Georgetown University School of Medicine, Washington D.C., 20007, USA., Department of Radiation Oncology, New York University Long Island School of Medicine, Mineola, MY, 11501, USA., Department of Radiation Oncology, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave., New York, NY, 10023, USA., Department of Radiation Medicine, Lenox Hill Hospital - Northwell Health, New York, NY, 10075, USA., Department of Urology, New York University Long Island School of Medicine, Mineola, NY, 11501, USA., Department of Radiology, New York University Grossman School of Medicine, New York, NY, 10016, USA., Department of Radiation Medicine, Medstar Georgetown University Hospital, Washington D.C., 20007, USA., Department of Radiation Oncology, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave., New York, NY, 10023, USA. .

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