Hypofractionation results in reduced tumor cell kill compared to conventional fractionation for tumors with regions of hypoxia.
Purpose: Tumor hypoxia has been observed in many human cancers and is associated with treatment failure in radiation therapy. The purpose of this study is to quantify the effect of different radiation fractionation schemes on tumor cell killing, assuming a realistic distribution of tumor oxygenation...
| Publicado en: | International Journal of Radiation Oncology, Biology, Physics Vol. 79; no. 4; pp. 1188 - 1196 |
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| Autores principales: | , , , , , , , , , |
| Formato: | research Journal Article |
| Publicado: |
Pergamon Press - An Imprint of Elsevier Science
Mar2011
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=104832002&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 104832002 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 03603016 1ZQ jtl: International Journal of Radiation Oncology, Biology, Physics issn: 03603016 maglogo: N pubinfo: dt: Mar2011 vid: 79 iid: 4 pid: 2410 pub: Pergamon Press - An Imprint of Elsevier Science artinfo: ui: 104832002 NLM21183291 2010960555 10.1016/j.ijrobp.2010.10.007 NLM21183291 PMC3053128 104832002 ppf: 1188 ppct: 8 formats: tig: atl: Hypofractionation results in reduced tumor cell kill compared to conventional fractionation for tumors with regions of hypoxia. aug: au: Carlson DJ Keall PJ Loo BW Jr Chen ZJ Brown JM Carlson, David J Keall, Paul J Loo, Billy W Jr Chen, Zhe J Brown, J Martin affil: Stanford University School of Medicine, Department of Radiation Oncology, Stanford, CA, USA sug: subj: Cell Physiology Radiation Effects Radiation Dosage Oxygen Consumption Physiology Radiation Algorithms Capillaries Anatomy and Histology Capillaries Metabolism Cell Physiology Drug Effects Head and Neck Neoplasms Metabolism Head and Neck Neoplasms Radiotherapy Human Linear Regression Male Imidazoles Pharmacodynamics Partial Pressure Prostatic Neoplasms Metabolism Prostatic Neoplasms Radiotherapy Radiation-Sensitizing Agents Pharmacodynamics Treatment Failure Male ab: Purpose: Tumor hypoxia has been observed in many human cancers and is associated with treatment failure in radiation therapy. The purpose of this study is to quantify the effect of different radiation fractionation schemes on tumor cell killing, assuming a realistic distribution of tumor oxygenation.Methods and Materials: A probability density function for the partial pressure of oxygen in a tumor cell population is quantified as a function of radial distance from the capillary wall. Corresponding hypoxia reduction factors for cell killing are determined. The surviving fraction of a tumor consisting of maximally resistant cells, cells at intermediate levels of hypoxia, and normoxic cells is calculated as a function of dose per fraction for an equivalent tumor biological effective dose under normoxic conditions.Results: Increasing hypoxia as a function of distance from blood vessels results in a decrease in tumor cell killing for a typical radiotherapy fractionation scheme by a factor of 10(5) over a distance of 130 μm. For head-and-neck cancer and prostate cancer, the fraction of tumor clonogens killed over a full treatment course decreases by up to a factor of ∼10(3) as the dose per fraction is increased from 2 to 24 Gy and from 2 to 18 Gy, respectively.Conclusions: Hypofractionation of a radiotherapy regimen can result in a significant decrease in tumor cell killing compared to standard fractionation as a result of tumor hypoxia. There is a potential for large errors when calculating alternate fractionations using formalisms that do not account for tumor hypoxia. pubtype: Academic Journal doctype: research Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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