Association between metabolic and pathologic response after neoadjuvant CRT for NSCLC
maria gonzalez de dueñas,
Spain
PO-1315
Abstract
Association between metabolic and pathologic response after neoadjuvant CRT for NSCLC
Authors: maria gonzalez de dueñas1, Joaquin Cabrera Rodriguez2, Carmen Corral Fernandez3, Victoria Vera Barragán3, Esther Agudo Rey3, Maria Medina Cobacho3, Yesika Rios Kavadoy4, Juan Quirós Rivero3, Maria Francisca Ropero Carmona5, Julia Muñoz Garcia3, Teresa Pilar Iglesias Garcia3, Fernando Garcia Urra3
1Hospital Universitario de Badajoz, Radiotherapy Oncology, Badajoz, Spain; 2Hospital Universitario de Badajoz, radiotherapy oncology, Badajoz, Spain; 3Hospital Universitario de Badajoz, radiotherapy oncology, Badajoz, Spain; 4Hospital Universitario de Badajoz, radiotherapy oncology, Badajoz,, Spain; 5Hospital Universitario de Badajoz,, radiotherapy oncology, Badajoz, Spain
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Purpose or Objective
To assess the prognostic value of the association between post-CRT [18F]FDG PET/CT metabolic response and pathologic response in patients treated with neoadjuvant CRT (neoCRT) plus surgery for NSCLC.
Material and Methods
Retrospective study of patients treated with neoCRT according to institutional protocol as per Multidisciplinary Tumor Board (MTB) consensus. All patients underwent a pre-treatment [18F]FDG PET/CT. After completing neoCRT they had a second post-treatment PET/CT scheduled at week +4. Patients had surgery between at week +6 to +8 if MTB deemed the case resectable after evaluation of tumor response .
Results
60 patients received neoCRT consisting of platinum-based doublet plus concomitant thoracic radiotherapy (60 Gy) of whom 43 ultimately underwent surgery and were included for analysis. The median follow-up was 5.5 years. The median OS has not been reached, mean OS was 10.1 years. Metabolic complete response (mCR) was obtained in 13 (30.2%) pathological CR (pCR) in 16 (37.2%) of whom 6 had metabolic partial response (mRP). 7 patients (16.3%) achieved both mCR and pCR. The sensitivity and specificity of [18F]FDG PET/CT for predicting pathologic response was 77.8% and 56.2% respectively. PPV and NPV was 70% and 53.8% respectively. 5-year OS for patients who achieved both mCR plus pCR was 100%, p = 0.04, compared with those who had persistent disease of any type: mPR plus pCR: 62%, mCR plus pPR: 50 %, mPR plus pPR: 44%. OS differences between the last 3 groups were not significant.
Conclusion
Patients with NSCLC treated with neoCRT plus surgery who achieve both mCR and pCR have an excellent prognosis. Although both the sensitivity and specificity of [18F]FDG PET/CT have shown a poor performance diagnosing histological response, the prognostic value of PET/CT seems to be important since a positive post-treatment result (e.g. mPR) influences OS even in patients without pathological residual tumor (pCR).