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Zietman, Anthony

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Zietman

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Anthony

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Zietman, Anthony
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    Dosimetric impacts of endorectal balloon in CyberKnife stereotactic body radiation therapy (SBRT) for early‐stage prostate cancer
    (John Wiley and Sons Inc., 2017) Xiang, Hong F.; Lu, Hsiao‐Ming; Efstathiou, Jason; Zietman, Anthony; Armas, Ricardo De; Harris, Kathryn; Bloch, B. Nicolas; Qureshi, Muhammad Mustafa; Keohan, Sean; Hirsch, Ariel E.
    Abstract Purpose In SBRT for prostate cancer, higher fractional dose to the rectum is a major toxicity concern due to using smaller PTV margin and hypofractionation. We investigate the dosimetric impact on rectum using endorectal balloon (ERB) in prostate SBRT. Materials and Methods Twenty prostate cancer patients were included in a retrospective study, ten with ERB and 10 without ERB. Optimized SBRT plans were generated on CyberKnife MultiPlan for 5 × 7.25 Gy to PTV under RTOG‐0938 protocol for early‐stage prostate cancer. For the rectum and the anterior half rectum, mean dose and percentage of volumes receiving 50%, 80%, 90%, and 100% prescription dose were compared. Results: Using ERB, mean dose to the rectum was 62 cGy (P = 0.001) lower per fraction, and 50 cGy (P = 0.024) lower per fraction for the anterior half rectum. The average V50%, V80%, V90%, and V100% were lower by 9.9% (P = 0.001), 5.3% (P = 0.0002), 3.4% (P = 0.0002), and 1.2% (P = 0.005) for the rectum, and lower by 10.4% (P = 0.009), 8.3% (P = 0.0004), 5.4% (P = 0.0003), and 2.1% (P = 0.003) for the anterior half rectum. Conclusions: Significant reductions of dose to the rectum using ERB were observed. This may lead to improvement of the rectal toxicity profiles in prostate SBRT.
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    Contemporary accuracy of death certificates for coding prostate cancer as a cause of death: Is reliance on death certification good enough? A comparison with blinded review by an independent cause of death evaluation committee
    (Nature Publishing Group, 2016) Turner, Emma L; Metcalfe, Chris; Donovan, Jenny L; Noble, Sian; Sterne, Jonathan A C; Lane, J Athene; I Walsh, Eleanor; Hill, Elizabeth M; Down, Liz; Ben-Shlomo, Yoav; Oliver, Steven E; Evans, Simon; Brindle, Peter; Williams, Naomi J; Hughes, Laura J; Davies, Charlotte F; Ng, Siaw Yein; Neal, David E; Hamdy, Freddie C; Albertsen, Peter; Reid, Colette M; Oxley, Jon; McFarlane, John; Robinson, Mary C; Adolfsson, Jan; Zietman, Anthony; Baum, Michael; Koupparis, Anthony; Martin, Richard M
    Background: Accurate cause of death assignment is crucial for prostate cancer epidemiology and trials reporting prostate cancer-specific mortality outcomes. Methods: We compared death certificate information with independent cause of death evaluation by an expert committee within a prostate cancer trial (2002–2015). Results: Of 1236 deaths assessed, expert committee evaluation attributed 523 (42%) to prostate cancer, agreeing with death certificate cause of death in 1134 cases (92%, 95% CI: 90%, 93%). The sensitivity of death certificates in identifying prostate cancer deaths as classified by the committee was 91% (95% CI: 89%, 94%); specificity was 92% (95% CI: 90%, 94%). Sensitivity and specificity were lower where death occurred within 1 year of diagnosis, and where there was another primary cancer diagnosis. Conclusions: UK death certificates accurately identify cause of death in men with prostate cancer, supporting their use in routine statistics. Possible differential misattribution by trial arm supports independent evaluation in randomised trials.
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    Interfractional Variations in the Setup of Pelvic Bony Anatomy and Soft Tissue, and Their Implications on the Delivery of Proton Therapy for Localized Prostate Cancer
    (Elsevier BV, 2011) Trofimov, Alexei; Nguyen, Paul; Efstathiou, Jason; Wang, Yi; Lu, Hsiao-Ming; Engelsman, Martijn; Merrick, Scott; Cheng, Chee-Wai; Wong, James R.; Zietman, Anthony
    Purpose To quantify daily variations in the anatomy of patients undergoing radiation therapy for prostate carcinoma, to estimate their effect on dose distribution, and to evaluate the effectiveness of current standard planning and set-up approaches employed in proton therapy. Methods We used series of CT data, which included the pre-treatment scan, and between 21 and 43 in-room scans acquired on different treatment days, from 10 patients treated with intensity-modulated radiation therapy at Morristown Memorial Hospital. Variations in femur rotation angles, thickness of subcutaneous adipose tissue, and physical depth to the distal surface of the prostate for lateral beam arrangement were recorded. Proton dose distributions were planned with the standard approach. Daily variations in the location of the prescription iso-dose were evaluated. Results In all 10 datasets, substantial variation was observed in the lateral tissue thickness (standard deviation of 1.7–3.6 mm for individual patients, variations of over 5 mm from the planning CT observed in all series), and femur rotation angle (standard deviation between 1.3–4.8°, with the maximum excursion exceeding 10° in 6 out of 10 datasets). Shifts in the position of treated volume (98% iso-dose) were correlated with the variations in the lateral tissue thickness. Conclusions Analysis suggests that, combined with image-guided set-up verification, the range compensator expansion technique prevents loss of dose to target due to femur rotation and soft tissue deformation, in the majority of cases. Anatomic changes coupled with the uncertainties of particle penetration in tissue restrict possibilities for margin reduction in proton therapy of prostate cancer.