Prognostic value of post-induction chemotherapy 18F-FDG PET-CT in stage II/III non-small cell lung cancer before (chemo-) radiation

Abstract

IntroductionThe purpose of our present study was to assess the prognostic impact of FDG PET-CT after induction chemotherapy for patients with inoperable non-small-cell lung cancer (NSCLC).Material and methodsThis retrospective study included 50 patients with inoperable stage II/III NSCLC from January 2012 to July 2015. They were treated for curative intent with induction chemotherapy, followed by concomitant chemoradiation therapy or sequential radiation therapy. FDG PET-CT scans were acquired at initial staging (PET1) and after the last cycle of induction therapy (PET2). Five parameters were evaluated on both scans: SUVmax, SUVpeak, SUVmean, TLG, MTV, and their respective deltas. The prognostic value of each parameter for overall survival (OS) and progression-free survival (PFS) was evaluated with Cox proportional-hazards regression models.ResultsMedian follow-up was 19 months. PET1 parameters, clinical and histopathological data were not predictive of the outcome. TLG2 and ΔTLG were prognostic factors for OS. TLG2 was the only prognostic factor for PFS. For OS, log-rank test showed that there was a better prognosis for patients with TLG2< 69g (HR = 7.1, 95%CI 2.8–18, p = 0.002) and for patients with ΔTLG< -81% after induction therapy (HR = 3.8, 95%CI 1.5–9.6, p = 0.02). After 2 years, the survival rate was 89% for the patients with low TLG2 vs 52% for the others. We also evaluated a composite parameter considering both MTV2 and ΔSUVmax. Patients with MTV2> 23cc and ΔSUVmax> -55% had significantly shorter OS than the other patients (HR = 5.7, 95%CI 2.1–15.4, p< 0.01).ConclusionPost-induction FDG PET might be an added value to assess the patients’ prognosis in inoperable stage II/III NSCLC. TLG, ΔTLG as well as the association of MTV and ΔSUVmax seemed to be valuable parameters, more accurate than clinical, pathological or pretherapeutic imaging data.

Value of PET imaging for radiation therapy

“…This is due to their high physiological glucose consumption, leading to a low tumour-to-background contrast and sensitivity for [ 18 F]FDG, as well as to a high glucose uptake of inflammatory cells, which particularly hampers the evaluation of equivocal lesions after radiotherapy [1][2][3]. Therefore, amino acid tracers such as [ 18 [ 18 F]FDOPA or [ 18 F]fluciclovine ([ 18 F]FACBC) are recommended for the assessment of gliomas and brain metastases [4,5], while radiolabelled ligands of the somatostatin receptor type 2 (SSR2; e. g. [ 68 Ga]Ga-DOTATOC, [ 68 Ga]Ga-DOTATATE, or [ 18 F]SIFATATE) are used for the imaging of meningiomas due to their overexpression of the SSR2 [6].…”

“…Serial PET scans, combined with CT or MRI, have been investigated in multimodality protocols during induction treatment before radiotherapy or during definitive RCHT aiming at either acquiring prognostic information or defining individualized treatment adaptation [61][62][63]. Semi-quantitative metabolic FDG-PET parameters [i. e. maximum standardised uptake value (SUV max ), metabolic tumour volume (MTV)] during RCHT have been observed to significantly correlate with overall and progression free survival, and/or local tumour control, even when reassessment is performed early (at 2 or 3 weeks after the start of radiotherapy) [64][65][66][67][68][69][70]. Newer approaches using radiomics and artificial intelligence are under investigation, but robust independent features, including 4D-PET imaging, were not of complementary prognostic or predictive value [59,71,72].…”

“…However, it can be assumed that the intraprostatic tumour mass determined on the basis of PSMA-PET information can be contoured with a higher sensitivity [161][162][163][164]. Zamboglou et al [165] reported on the feasibility of dose escalation to intraprostatic lesions defined by [ 68 Ga]Ga-PSMA to 95 Gy in 10 patients. Thus, a multicentre phase II study from Germany is currently investigating focal dose escalation to intraprostatic tumour volumes defined by combined PSMA-PET/CT and MRI imaging (HypoFocal; DRKS00017570).…”

“…Most studies used 68 Ga-labelled PSMA compounds, however, these are more and more replaced by 18 F-labelled PSMA tracers, as these can be produced in higher quantities and also mostly have less renal excretion, thus showing superior image quality adjacent to the bladder for identification of local recurrences [176]. Recent reports also suggest that PET/MRI might be advantageous in this respect and superior to PET/CT for detection of local recurrences [177,178].…”

Prognostic Value of Postinduction Chemotherapy Volumetric PET/CT Parameters for Stage IIIA or IIIB Non–Small Cell Lung Cancer Patients Receiving Definitive Chemoradiotherapy

“…Limited evidence is available that metabolic tumor volume (MTV) or parameters based on MTV like total lesion glycolysis (TLG), are prognostic for stage III NSCLC patients treated with definitive chemoradiotherapy after induction chemotherapy. Ganem et al assessed the influence of post-induction chemotherapy TLG on progression-free survival in 50 stage II/III NSCLC patients, and concluded that post-induction 18 F-FDG-PET metrics might add value to estimate patients' prognosis (6). Soussan et al also found a prognostic value of TLG in 33 stage III NSCLC patients, receiving induction chemotherapy and surgery or definitive radio-or chemoradiotherapy (7).…”