Early FDG-PET imaging after radical radiotherapy for non-small-cell lung cancer: inflammatory changes in normal tissues correlate with tumor response and do not confound therapeutic response evaluation

Int J Radiat Oncol Biol Phys. 2004 Oct 1;60(2):412-8. doi: 10.1016/j.ijrobp.2004.03.036.


Purpose: To investigate the relationship between positron emission tomography (PET) detected inflammatory changes in irradiated normal tissues and metabolic response at tumor sites in patients receiving radical radiotherapy for non-small-cell lung cancer. The prognostic significance of these changes was also studied.

Methods: In 73 consecutive patients, (18)F-fluorodeoxyglucose (FDG) PET was performed at a median of 70 days after completion of radical radiotherapy. Radiation-induced inflammatory change was scored for normal tissues within the radiation treatment volume using a 0-3 grading scale. Metabolic tumor response was assessed using a pattern-recognition algorithm comparing pre- and posttreatment scans. Prognostic significance of inflammatory changes was tested using the Cox proportional hazards regression model.

Results: Increased FDG uptake in normal tissues (radiotoxicity) was associated with a greater likelihood of complete or partial tumor response on both PET (p = 0.0044) and computed tomography (p = 0.029). Prognostic stratification provided by PET response was both significant and of a similar magnitude in patients with low- and high-grade radiotoxicity.

Conclusion: Postradiotherapy inflammatory changes detected by FDG-PET are positively correlated with tumor response, suggesting that tumor radioresponsiveness and normal tissue radiosensitivity may be linked. Prognostic stratification provided by PET is not compromised by inflammatory changes if a meticulous visual response assessment technique is used.

MeSH terms

  • Adenocarcinoma / diagnostic imaging
  • Adenocarcinoma / radiotherapy
  • Carcinoma, Non-Small-Cell Lung / diagnostic imaging
  • Carcinoma, Non-Small-Cell Lung / mortality
  • Carcinoma, Non-Small-Cell Lung / radiotherapy*
  • Carcinoma, Squamous Cell / diagnostic imaging
  • Carcinoma, Squamous Cell / radiotherapy
  • Fluorodeoxyglucose F18* / pharmacokinetics
  • Humans
  • Lung / diagnostic imaging*
  • Lung / metabolism
  • Lung Neoplasms / diagnostic imaging
  • Lung Neoplasms / mortality
  • Lung Neoplasms / radiotherapy*
  • Prognosis
  • Prospective Studies
  • Radiopharmaceuticals* / pharmacokinetics
  • Tomography, Emission-Computed*


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18