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Predicting the effect of temporal variations in PO2 on tumor radiosensitivity.

Publication ,  Journal Article
Kirkpatrick, JP; Cárdenas-Navia, LI; Dewhirst, MW
Published in: Int J Radiat Oncol Biol Phys
July 1, 2004

PURPOSE: Tumor hypoxia is associated with less effective radiation-mediated cell killing, increased metastatic potential, and poorer prognosis. Transient variations in hypoxia, with characteristic periodicity on the order of 1 to 10 min, have been observed in animal models. This article explores the effect of these temporal variations in PO(2) on the oxygen enhancement ratio, effective radiation dose to the tumor, and tumor control probability. METHODS AND MATERIALS: PO(2) over a 50-60 min period was determined at multiple sites in rat fibrosarcomas, 9L gliomas, and R3230Ac mammary adenocarcinomas. Using a correlation derived from the data of Elkind et al. (1965), PO(2) data are converted into oxygen enhancement ratios (OERs.) A tumor is assumed to consist of 10(3)-10(4) independent oxygenation subvolumes, each with a randomly chosen starting point on the OER-time curve. The effect of temporal variations in OER is examined for three cases: conventionally fractionated external beam radiotherapy (EBRT), stereotactic radiosurgery (SRS) and intraoperative radiotherapy (IORT). The oxygen effective dose (OED) for a subvolume is calculated from the dose to that subvolume modified by the OER. In turn, the distribution of OED for a tumor is analyzed for each treatment case and representative tumor control probabilities (TCPs) calculated. RESULTS: Oxygen enhancement ratio varied from 1 to 3 over the range of PO(2) measured in this study. Mean OER ranged from 1.6 to 2.6, and the variation in OER vs. time was greater with decreasing PO(2). In EBRT, the standard deviation in OED was small, <2%. In contrast, the standard deviation in OED was much higher for both SRS and IORT, typically ranging from 3 to 6%, with the greatest variation at the lowest PO(2)s. Compared with a tumor with equal mean OED and uniform PO(2), TCP was minimally poorer for either EBRT or well-oxygenated tumors. However, for both SRS and IORT, temporal variations in more hypoxic tumors can produce a significant decrease in TCP. CONCLUSION: Temporal variations in tumor PO(2) can produce significant variations OER, particularly at low PO(2), resulting in decreased TCP for hypofractionated treatment regimens.

Duke Scholars

Published In

Int J Radiat Oncol Biol Phys

DOI

ISSN

0360-3016

Publication Date

July 1, 2004

Volume

59

Issue

3

Start / End Page

822 / 833

Location

United States

Related Subject Headings

  • Time Factors
  • Rats, Inbred F344
  • Rats
  • Radiosurgery
  • Radiation Tolerance
  • Partial Pressure
  • Oxygen
  • Oncology & Carcinogenesis
  • Neoplasms
  • Intraoperative Period
 

Citation

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MLA
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Kirkpatrick, J. P., Cárdenas-Navia, L. I., & Dewhirst, M. W. (2004). Predicting the effect of temporal variations in PO2 on tumor radiosensitivity. Int J Radiat Oncol Biol Phys, 59(3), 822–833. https://doi.org/10.1016/j.ijrobp.2004.02.015
Kirkpatrick, J. P., L. I. Cárdenas-Navia, and M. W. Dewhirst. “Predicting the effect of temporal variations in PO2 on tumor radiosensitivity.Int J Radiat Oncol Biol Phys 59, no. 3 (July 1, 2004): 822–33. https://doi.org/10.1016/j.ijrobp.2004.02.015.
Kirkpatrick JP, Cárdenas-Navia LI, Dewhirst MW. Predicting the effect of temporal variations in PO2 on tumor radiosensitivity. Int J Radiat Oncol Biol Phys. 2004 Jul 1;59(3):822–33.
Kirkpatrick, J. P., et al. “Predicting the effect of temporal variations in PO2 on tumor radiosensitivity.Int J Radiat Oncol Biol Phys, vol. 59, no. 3, July 2004, pp. 822–33. Pubmed, doi:10.1016/j.ijrobp.2004.02.015.
Kirkpatrick JP, Cárdenas-Navia LI, Dewhirst MW. Predicting the effect of temporal variations in PO2 on tumor radiosensitivity. Int J Radiat Oncol Biol Phys. 2004 Jul 1;59(3):822–833.
Journal cover image

Published In

Int J Radiat Oncol Biol Phys

DOI

ISSN

0360-3016

Publication Date

July 1, 2004

Volume

59

Issue

3

Start / End Page

822 / 833

Location

United States

Related Subject Headings

  • Time Factors
  • Rats, Inbred F344
  • Rats
  • Radiosurgery
  • Radiation Tolerance
  • Partial Pressure
  • Oxygen
  • Oncology & Carcinogenesis
  • Neoplasms
  • Intraoperative Period