A radiobiological study of the schemes with a low number of fractions in high-dose-rate brachytherapy as monotherapy for prostate cancer

• Published in: Journal of contemporary brachytherapy Vol. 12; no. 2; pp. 193 - 200
• Main Authors: Guirado, Damián, Ruiz-Arrebola, Samuel, Tornero-López, Ana M, de la Vega, Jose M, Prada, Pedro J, Lallena, Antonio M
• Format: Journal Article
• Language: English
• Published: Poland Termedia Publishing House 01.04.2020
• Subjects: Computer simulation; Fractionation; hdr brachytherapy; monotherapy; Monte Carlo simulation; Original Paper; Prostate cancer; Radiation dosage; Radiation therapy; Schedules; Statistical analysis; Statistical methods; prostate cancer; monotherapy; HDR brachytherapy
• ISSN: 1689-832X; 2081-2841
• DOI: 10.5114/jcb.2020.94492

Schemes with high doses per fraction and small number of fractions are commonly used in high-dose-rate brachytherapy (HDR-BT) for prostate cancer. Our aim was to analyze the differences between published clinical results and the predictions of radiobiological models for absorbed dose required in a single fraction monotherapy HDR-BT. Published HDR-BT clinical results for low- and intermediate-risk patients with prostate cancer were revised. For 13 clinical studies with 16 fractionation schedules between 1 and 9 fractions, a dose-response relation in terms of the biochemical control probability (BC) was established using Monte Carlo-based statistical methods. We obtained a value of α/β = 22.8 Gy (15.1-60.2 Gy) (95% CI) much larger than the values in the range 1.5-3.0 Gy that are usually considered to compare the results of different fractionation schemes in prostate cancer radiotherapy using doses per fraction below 6 Gy. The doses in a single fraction producing BC = 90% and 95% were 22.3 Gy (21.5-24.2 Gy) and 24.3 Gy (23.0-27.9 Gy), respectively. The α/β obtained in our analysis of 22.8 Gy for a range of dose per fraction between 6 and 20.5 Gy was much greater than the one currently estimated for prostate cancer using low doses per fraction. This high value of α/β explains reasonably well the data available in the region of high doses per fraction considered.