Abstract
Introduction: CT alone cannot provide sufficient information referring to response after neoadjuvant therapy in a timely manner. To evaluate the role of 18F-FDG-PET after neoadjuvant chemoradiation as a valid, non-invasive predictor for early therapy response and its effect on survival as compared to histopathologic tumor response, data of 32 of 210 randomized patients with NSCLC stage IIIA/IIIB, who were treated in a prospective randomized controlled multicenter trial (LUCAS- MD), were re-evaluated. Material and Methods: For 32 patients with NSCLC stage IIIA (44%) IIIB (56%) neoadjuvant treatment consisted of two to three cycles of chemotherapy (225 mg/m2 paclitaxel and carboplatin AUC 6 d1q22) and concomitant chemoradiation (50 mg/m2 paclitaxel and carboplatin AUC 2 d1, d8, d15; 1.5 Gy b.i.d. up to 45 Gy). Documentation of involved lymph node stations as detected by 18F-FDG-PET/CT and lymph node sampling during surgery according to the IASLC lymph node mapping (2009). Evaluation of histological regression grade (RG) according to Junker et al. (2001) and correlation with 18F-FDG-PET/CT for primary tumor and each lymph node station. Calculation of disease free survival using Kaplan-Meier estimates and log rank tests. Results: Actuarial tumor specific survival for the 32 patients with concomitant chemoradiation plus chemotherapy: complete vs. incomplete metabolic remission prior to surgery after 60 months: 40% vs. 24% (p = 0.018). RG III/IIb (no/less than 10% of vital tumor cells) vs. RG IIa/I (more than 10% vital tumor cells) after 60 months: 46% vs. 15% (p = 0.006). 18/32 (56%) patients had RG III/IIb, 8/32 (25%) patients had regression grade III. 1/8 pts. with RG III were in the 18F-FDG- PET/CT false positive, 10 pts. with RG IIb (i.e. all pts. with RG IIb) were in the 18F-FDG-PET/CT false negative. One patient with RG IIa was in the 18F-FDG-PET/CT false negative. Hence, the cut-off level in detecting vital tumor cells by 18F-FDG-PET/CT after neoadjuvant chemoradiation for NSCLC is about 10%. Conclusion: Histological regression grading correlates well with metabolic remission as detected by 18F-FDG-PET. Thus, 18F-FDG-PET precedes CT in measuring the tumor response and may predict long-term therapeutic outcome in patients with stage III NSCLC. Invasive staging procedures may be avoided and patients who will not profit from resection due to insufficient downstaging after neoadjuvant treatment will be easily detected by using 18F-FDG-PET as standard imaging in workup and evaluation of treatment response.
Highlights
computed tomography (CT) alone cannot provide sufficient information referring to response after neoadjuvant therapy in a timely manner
Invasive staging procedures may be avoided and patients who will not profit from resection due to insufficient downstaging after neoadjuvant treatment will be detected by using 18F-FDG-positron emission tomography (PET) as standard imaging in workup and evaluation of treatment response
During surgery lymph node sampling according to IASLC recommendations was done, to correlate histology with the results found in CT and 18F-FDG-PET [31] [32]. 2.4
Summary
CT alone cannot provide sufficient information referring to response after neoadjuvant therapy in a timely manner. To evaluate the role of 18F-FDG-PET after neoadjuvant chemoradiation as a valid, non-invasive predictor for early therapy response and its effect on survival as compared to histopathologic tumor response, data of 32 of 210 randomized patients with NSCLC stage IIIA/IIIB, who were treated in a prospective randomized controlled multicenter trial (LUCASMD), were re-evaluated. Results: Actuarial tumor specific survival for the 32 patients with concomitant chemoradiation plus chemotherapy: complete vs incomplete metabolic remission prior to surgery after 60 months: How to cite this paper: Klass, N.D., et al (2014) Is 18F-FDG-PET/CT a Valid Non-Invasive Predictor for Regression Grade after Neoadjuvant Treatment in Patients with NSCLC Stage III? In over 70% of the first hilar lymph nodes followed by mediastinal and supraclavicular lymph nodes are involved This fact depends on the histology of the tumor: 33% of squamous cell tumors, 54% of adenocarcinomas and 57% of non-differentiated tumors present lymph node metastases at diagnosis. At the same time even very small tumors tend to metastasize quite early so that lung cancer is a systemic disease
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