Y Trada MB BS; A Plank PhD; J Martin FRANZCR.
Radiation Oncology—Original Article
Defining a dose–response relationship for prostate external beam radiotherapy
Article first published online: 28 DEC 2012
© 2012 The Authors. Journal of Medical Imaging and Radiation Oncology © 2012 The Royal Australian and New Zealand College of Radiologists
Journal of Medical Imaging and Radiation Oncology
Volume 57, Issue 2, pages 237–246, April 2013
How to Cite
Trada, Y., Plank, A. and Martin, J. (2013), Defining a dose–response relationship for prostate external beam radiotherapy. Journal of Medical Imaging and Radiation Oncology, 57: 237–246. doi: 10.1111/1754-9485.12008
Conflict of interest: None.
- Issue published online: 2 APR 2013
- Article first published online: 28 DEC 2012
- Manuscript Accepted: 9 SEP 2012
- Manuscript Received: 28 MAY 2012
- biochemical failure;
- dose–response relationship;
- prostatic neoplasm;
- systemic review
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).
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.
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 (TCD50) is 52.0 Gy and the slope of the dose–response curve at TCD50 (γ50) is 2.1%/Gy. At 78 Gy this represented a FFBF of 90.3%. In intermediate-risk patients not treated with HT the TCD50 is 64.7 Gy and γ50 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.
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.