Measurement of Tumor Hypoxia in Patients With Locally Advanced Cervical Cancer Using Positron Emission Tomography with 18 F-Fluoroazomyin Arabinoside

Int J Radiat Oncol Biol Phys. 2018 Nov 15;102(4):1202-1209. doi: 10.1016/j.ijrobp.2018.02.030. Epub 2018 Mar 2.

Abstract

Purpose: To assess cervical tumor hypoxia using the hypoxia tracer 18F-fluoroazomycin arabinoside (18F-FAZA) and compare different reference tissues and thresholds for quantifying tumor hypoxia.

Methods and materials: Twenty-seven patients with cervical cancer were studied prospectively by positron emission tomography (PET) imaging with 18F-FAZA before starting standard chemoradiation. The hypoxic volume was defined as all voxels within a tumor (T) with standardized uptake values (SUVs) greater than 3 standard deviations from the mean gluteus maximus muscle SUV value (M) or SUVs greater than 1 to 1.4 times the mean SUV value of the left ventricle, a blood (B) surrogate. The hypoxic fraction was defined as the ratio of the number of hypoxic voxels to the total number of tumor voxels.

Results: A 18F-FAZA-PET hypoxic volume could be identified in the majority of cervical tumors (89% when using T/M or T/B > 1.2 as threshold) on the 2-hour static scan. The hypoxic fraction ranged from 0% to 99% (median 31%) when defined using the T/M threshold and from 0% to 78% (median 32%) with the T/B > 1.2 threshold. Hypoxic volumes derived from the different thresholds were highly correlated (Spearman's correlation coefficient ρ between T/M and T/B > 1-1.4 were 0.82-0.91), as were hypoxic fractions (0.75-0.85). Compartmental analysis of the dynamic scans showed k3, the FAZA accumulation constant, to be strongly correlated with hypoxic fraction defined using the T/M (Spearman's ρ=0.72) and T/B > 1.2 thresholds (0.76).

Conclusions: Hypoxia was detected in the majority of cervical tumors on 18F-FAZA-PET imaging. The extent of hypoxia varied markedly between tumors but not significantly with different reference tissues/thresholds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Fluorine Radioisotopes*
  • Humans
  • Middle Aged
  • Misonidazole / analogs & derivatives
  • Nitroimidazoles*
  • Positron-Emission Tomography / methods*
  • Prospective Studies
  • Radiopharmaceuticals*
  • Tumor Hypoxia*
  • Uterine Cervical Neoplasms / diagnostic imaging
  • Uterine Cervical Neoplasms / metabolism*

Substances

  • Fluorine Radioisotopes
  • Nitroimidazoles
  • Radiopharmaceuticals
  • fluoromisonidazole
  • fluoroazomycin arabinoside
  • Misonidazole