Restaging Patients with N2 (Stage IIIa) Non-Small Cell Lung Cancer after Neoadjuvant Chemoradiotherapy: A Prospective Study
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OBJECTIVE:To assess the accuracy of re-staging patients with stage IIIa non-small cell lung cancer after neoadjuvant chemoradiotherapy.
METHODS:A prospective trial of patients with biopsy proven N2 disease who underwent initial clinical staging with mediastinoscopy and integrated PET/CT and CT scans. Patients were then clinically re-staged by the same imaging techniques 4-12 weeks following their induction chemo-radiation therapy and then underwent definitive pathologic staging.
RESULTS:Ninety-three patients had their lymph nodes pathologically restaged. Repeat PET/CT after neoadjuvant therapy missed residual N2 disease in 13/65 patients (20%) and falsely suggested it in 7/28 (25%). It was more accurate than repeat CT for restaging at all pathologic stages (stage 0, 92% versus 39%, p=0.03 and stage I 89% versus 36%, p=0.04). When the maxSUV of the primary tumor decreased by > 75% it is highly likely (likelihood ratio, +LR, 6.1) the patient is a complete responder, when it decreased by > 55% it is highly likely (+LR 9.1) the patient is a partial responder. When the maxSUV of the N2 node initially involved with metastatic cancer decreased by greater than 50%, it is highly likely (+LR 7.9) the node is now benign.
CONCLUSIONS: Repeat integrated PET/CT is superior to repeat CT scan for the re-staging of patients with stage IIIa non-small cell lung cancer. The percent decrease in the maxSUV of the primary and of the involved lymph node is predictive of pathology, however nodal biopsies are required since a persistently high maxSUV does not equate to residual cancer.
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