| 1. |
- Fowler, Jack F., et al.
(författare)
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Is the α/β ratio for prostate tumours really low and does it vary with the level of risk at diagnosis?
- 2013
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Ingår i: Anticancer Research. - : International Institute of Anticancer Research (IIAR). - 0250-7005 .- 1791-7530. ; 33:3, s. 1009-1011
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To answer the questions: Is the α/β ratio (radiosensitivity to size of dose-per-fraction) really low enough to justify using a few large dose fractions instead of the traditional many small doses? Does this parameter vary with prognostic risk factors? Methods and Materials: Three large statistical overviews are critiqued, with results for 5,000, 6,000 and 14,000 patients with prostate carcinoma, respectively. Results: These major analyses agree in finding the average α/β ratio to be less than 2 Gy: 1.55, (95% confidence interval=0.46-4.52), 1.4 (0.9-2.2), and the third analysis 1.7 (1.4-2.2) by ASTRO and 1.6 (1.2-2.2) by Phoenix criteria. All agree that α/β values do not vary significantly with the low, intermediate, high and “all included” risk factors. Conclusion: The high sensitivity to dose-per-fraction is an intrinsic property of prostate carcinomas and this supports the use of hypofractionation to increase the therapeutic gain for these tumours with dose-volume modelling to reduce the risk of late complications in rectum and bladder.
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| 2. |
- Mohanty, Chitralekha, et al.
(författare)
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Predicting the sensitivity to ion therapy based on the response to photon irradiation - experimental evidence and mathematical modelling
- 2014
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 34:6, s. 2801-2806
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aim: The use of ion radiation therapy is growing due to the continuously increasing positive clinical experience obtained. Therefore, there is a high interest in radio-biological experiments comparing the relative efficiency in cell killing of ions and photons as the photons are currently the main radiation modality used for cancer treatment. This comparison is particularly important since the treatment planning systems (TPSs) used at the main ion therapy centres make use of parameters describing the cellular response to photons, respectively ions, determined in vitro. It was therefore the aim of this paper to compare the effects of high LET ion radiation with low LET photons and determine whether the cellular response to low LET could predict the response to high LET irradiation. Materials and Methods: Clonogenic cell survival data of five tumor cell lines irradiated with different ion beams of similar, clinically-relevant, LET were studied in relation to the response to low LET photons. Two mathematical models were used to fit the data, the repairable-conditionally repairable damage (RCR) model and the linear quadratic (LQ) model. Results: The results indicate that the relative biological efficiency of the high LET radiation assessed with the RCR model could be predicted based only on the response to the low LET irradiation. Conclusion: The particular features of the RCR model indicate thus that tumor cells showing a large capacity for repairing the damage will have the larger benefit from radiation therapy with ions beams.
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