Positron-emission tomography CT to identify local recurrence in stage I lung cancer patients 1 year after stereotactic body radiation therapy

To evaluate the diagnostic value of positron-emission tomography/computed tomography (PET/CT) in stage I lung cancer patients treated with stereotactic body radiation therapy (SBRT), who have suspicious or unclear local recurrence findings in CT 1 year after treatment. A group of 29 patients with unclear or suspicious CT findings 1 year after SBRT were examined with PET/CT. The ability of standard uptake values (SUVmax, SUVmean and posttherapeutic reduction in SUV) to detect local failure and identify patients at a high risk of disease-specific death was evaluated using logrank statistics. Histology and clinical follow-up were the gold standards for local recurrence. SUVmean greater than 3.44 (p = 0.001); SUVmax greater than 5.48 (p = 0.009) or a relative reduction in SUVmean or SUVmax of less than 43 (p = 0.030) or 52 % (p = 0.025), respectively, was indicative of local recurrence. These parameters also correlated with an increased risk of disease-specific death: SUVmean greater than 2.81 (p = 0.023); SUVmax greater than 3.45 (p = 0.007) or a relative reduction in SUVmean or SUVmax of less than 32 (p = 0.015) or 52 % (p = 0.013), respectively, was indicative of an increased risk of disease-specific death. PET/CT performed 1 year after SBRT can reliably identify local recurrence and therefore help to clarify unclear CT findings. As posttherapeutic glucose metabolism also correlates with disease-specific survival, PET/CT may help to stratify lung cancer patients for additional treatment 1 year after SBRT.