Hypofractionated Prostate Radiation Therapy: Adoption and Dosimetric Adherence Through Clinical Pathways in an Integrated Oncology Network

PURPOSE: Updates to consensus guidelines in October 2018 recommending moderately hypofractionated external beam radiotherapy (mHF-EBRT) in prostate cancer lagged several years after publication of evidence supporting its efficacy. In January 2018, we amended our prostate cancer clinical pathway (CP) to facilitate adoption of mHF-EBRT. Herein, we analyze patterns of care and changes in mHF-EBRT use after the CP modification. METHODS: Our prostate CP was amended in January 2018 to make mHF-EBRT the recommended treatment for patients with low- and intermediate-risk prostate cancer pursuing curative EBRT monotherapy. Normal-tissue dose constraints accompanied the CP modification to guide planning. Use of mHF-EBRT from 2015 to 2017 was compared with use in 2018 after the CP modification, using the Cochran-Armitage test for trend. Predictors of mHF-EBRT use and adherence to dose constraints were analyzed with binary logistic regression. RESULTS: In 560 patients treated with EBRT monotherapy, mHF-EBRT use increased from 3.7% in 2015-2017 to 85.6% in 2018 ( P < .001), whereas conventionally fractionated EBRT (CF-EBRT) use decreased from 96.3% to 14.4% ( P < .001). Consultation year of 2018 (odds ratio [OR], 214.6; 95% CI, 94.5 to 484.6; P < .001), treatment at an academic facility (OR, 4.5; 95% CI, 1.8 to 11.3; P = 0.001), and having a smaller prostate (OR, 0.99; 95% CI, 0.97 to 1.00; P = .028) predicted for mHF-EBRT use. At least five of six recommended bladder and rectal dose constraints were met in 89.4% of patients. CONCLUSION: Modification of our prostate cancer CP, in concert with institutional policies to monitor and audit CP compliance, facilitated rapid adoption of mHF-EBRT in our large, integrated cancer center with good adherence to dosimetric constraints.

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Neurovascular bundle-sparing radiotherapy for prostate cancer using MRI-CT registration: A dosimetric feasibility study.

Journal of Clinical Oncology ◽

10.1200/jco.2016.34.2_suppl.128 ◽

2016 ◽

Vol 34 (2_suppl) ◽

pp. 128-128

Author(s):

Richard John Cassidy ◽

Xiaofeng Yang ◽

Tian Liu ◽

Sherif Nour ◽

Ashesh B. Jani

Keyword(s):

Prostate Cancer ◽

External Beam Radiotherapy ◽

Volumetric Modulated Arc Therapy ◽

Radiotherapy Planning ◽

Pelvic Mri ◽

Target Delineation ◽

High Risk Prostate Cancer ◽

Adequate Dose ◽

Risk Prostate Cancer ◽

Dose Constraints

128 Background: Sexual dysfunction after radiotherapy for prostate cancer remains an important late adverse toxicity. The neurovascular bundles (NVB) that lie postero-laterally to the prostate are typically spared during prostatectomy, but in traditional radiotherapy planning they are not contoured as an organ-at-risk with dose constraints. Our goal was to determine the feasibility in sparing the NVB while still delivering adequate dose to the prostate. Methods: Twelve consecutive patients with intermediate- or high-risk prostate cancer (with no gross disease within 2mm of either NVB) who were treated with external beam radiotherapy, with the same primary PTV margins, to a dose of 79.2 Gy were evaluated. Pelvic MRI and simulation CT scans were registered using dedicated software to allow for bilateral NVB target delineation on T2-weighted MRI. A volumetric modulated arc therapy (VMAT) plan was generated using the NVB bilaterally with 2mm margin as an organ to spare (with goal of reducing V70Gy by 30%) and compared to the patient’s delivered plan. Dose-volume histogram (DVH) endpoints for NVB, rectum, bladder, and PTV79.2 were compared between the two plans using a 2-tailed paired t-test. Results: The V70 for the NVB was significantly lower on the NVB sparing plan (p <0.01), while rectum and bladder endpoints were similar. Target V100% was lower (but still > 95%), and V105 was higher for the NVB Sparing plans (p <0.01). The table summarizes the DVH comparisons between the two plans. Conclusions: “NVB-sparing” radiotherapy is dosimetrically feasible using VMAT technology; target coverage is acceptable without increased dose to other normal structures, but with higher target dose inhomogeneity. The clinical impact of “NVH-sparing” radiotherapy is currently under study at our institution. [Table: see text]

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