Dosimetric Benefits of Hemi-Gland Stereotactic Body Radiotherapy for Prostate Cancer: Implications for Focal Therapy.

Compared to standard, whole gland (WG) therapies for prostate cancer, focal approaches may provide equivalent oncologic outcomes with fewer adverse effects. The purpose of this study was to compare organ-at-risk (OAR) dosimetry between hemi-gland (HG) and whole gland (WG) stereotactic body radiotherapy (SBRT) plans.

Volumetric arc radiotherapy-based SBRT plans were designed to treat the left HG, right HG, and WG in eight patients, using five fractions of 8 Gy. OARs of interest included the contralateral HG, rectum, urinary bladder, urethra, penile bulb, and contralateral neurovascular bundle.

Rectal V80% and V90% were significantly lower with HG plans than WG plans (median values of 4. 4 vs. 2. 5 cm(3) and 2. 1 vs. 1. 1 cc, respectively; p

Targeting a HG volume rather than a WG volume when delivering SBRT can offer statistically significant reductions for all OARs. Given the large magnitude of the reduction in dose to these OARs, it is anticipated that HG-SBRT could offer a superior toxicity profile when compared with WG-SBRT. This is likely to be most relevant in the context of salvaging a local failure after radiation therapy. Advances in knowledge: The dosimetric feasibility of HG-SBRT is demonstrated. When compared with WG-SBRT plans, the HG plans demonstrate statistically significant and large magnitude reduction in doses to the rectum, bladder, urethra, penile bulb, and contralateral neurovascular bundle, suggesting the possibility of improved toxicity outcomes with HG-SBRT. This is likely to be most relevant in the context of salvaging a local failure after radiation therapy.

The British journal of radiology. 2015 Oct 14 [Epub ahead of print]

Amar U Kishan, Sang June Park, Christopher R King, Kristofer Roberts, Patrick A Kupelian, Michael L Steinberg, Mitchell Kamrava

Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095. , Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095. , Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095. , Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095. , Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095. , Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095. , Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095.

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