Restaging patients with N2 (stage IIIa) non–small cell lung cancer after neoadjuvant chemoradiotherapy: A prospective study

BackgroundThe accuracy of restaging in patients with stage IIIa non–small cell lung cancer after neoadjuvant chemoradiotherapy is unknown.MethodsA prospective trial of patients with biopsy-proven N2 disease who underwent initial clinical staging with mediastinoscopy, integrated positron emission tomography/computed tomography (PET/CT), and CT. Patients then were clinically restaged by the same imaging techniques 4 to 12 weeks after their induction chemoradiation therapy and then underwent definitive pathologic staging.ResultsNinety-three patients had their lymph nodes pathologically restaged. Repeat PET/CT after neoadjuvant therapy missed residual N2 disease in 13/65 (20%) patients and falsely suggested it in 7 of 28 (25%). It was more accurate than repeat CT for restaging at all pathologic stages (stage 0, 92% vs 39%, P = .03; and stage I 89% vs 36%, P = .04). When the maximum standardized uptake value of the primary tumor is decreased by 75% or more, it is highly likely (likelihood ratio, +LR, 6.1) the patient is a complete responder; when it decreased by 55% or more, it is highly likely (+LR, 9.1) the patient is a partial responder. When the maximum standardized uptake value of the N2 node initially involved with metastatic cancer is decreased by more than 50%, it is highly likely (+LR, 7.9) the node is now benign.ConclusionRepeat integrated PET/CT is superior to repeat CT for the restaging of patients with stage IIIa non–small cell lung cancer. The percent decrease in the maximum standardized uptake value of the primary and of the involved lymph node is predictive of pathology; however, nodal biopsies are required since a persistently high maximum standardized uptake value does not equate to residual cancer.