Defining a dose–response relationship for prostate external beam radiotherapy. Issue 2 (28th December 2012)

• Record Type: Journal Article
• Authors: Trada, Yuvnik; Plank, Ash; Martin, Jarad
• Is Part Of: Journal of medical imaging and radiation oncology. Volume 57:Issue 2(2013:Apr.)
• Page Start: 237
• Page End: 246
• Publication Date: 2012-12-28
• Subjects: Radiology, Medical -- Periodicals; Radiology, Medical -- Australasia -- Periodicals; 616.0757
• DOI: 10.1111/1754-9485.12008
• Languages: English
• ISSNs: 1754-9477

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <sec id="jmiro12008-sec-0001" sec-type="section"> <title>Introduction</title> <p>We aimed to quantify a relationship between radiotherapy dose and freedom from biochemical failure (FFBF) in low‐ and intermediate‐risk prostate cancer. To reduce confounding we used data with a standardised end–point, mature follow‐up, low competing risk of metastatic failure, conventional fractionation and separate reporting for outcomes with hormonal therapy (HT).</p> </sec> <sec id="jmiro12008-sec-0002" sec-type="section"> <title>Methods</title> <p>A systematic review of the literature was carried out. Studies that reported the use of radiotherapy alone in 1.8–2 Gy fractions in low‐ and intermediate‐risk prostate cancer were included. The primary end–point was Phoenix definition 5‐year FFBF. A logistic regression was used to quantify the dose–response relationship.</p> </sec> <sec id="jmiro12008-sec-0003" sec-type="section"> <title>Results</title> <p>Data from eight studies with 3037 patients met the inclusion criteria. The data from 810 low‐risk patients and 2245 intermediate‐risk patients were analysed. A strong association between radiotherapy dose and FFBF was found in low‐ and intermediate‐risk patients managed with radiotherapy alone. In low‐risk patients not treated with HT the dose required to achieve 50% biochemical tumour control (TCD<sub>50</sub>) is 52.0 Gy and the slope of the dose–response curve at TCD<sub>50</sub> (γ<sub>50</sub>) is 2.1%/Gy. At 78 Gy this represented a FFBF of 90.3%. In intermediate‐risk patients not treated with HT the TCD<sub>50</sub> is 64.7 Gy and γ<sub>50</sub> is 3.2%/Gy. At 78 Gy this translated into a FFBF of 84.3%. HT had a small effect for low‐risk patients and an inconsistent effect for intermediate‐risk men.</p> </sec> <sec id="jmiro12008-sec-0004" sec-type="section"> <title>Conclusion</title> <p>A strong association was found between radiation dose and biochemical outcome in both low‐ and intermediate‐risk patients. Standardised reporting of results from future studies will make future analyses more robust.</p> </sec> </abstract>