Prognostic value of volumetric metabolic parameter changes determined by during and after radiotherapy‐based ¹⁸F‐FDG PET/CT in stage III non‐small cell lung cancer

Abstract

The aim of this prospective study was to evaluate the prognostic value of volumetric metabolic parameters assessed by during and after radiation‐based therapy 18F‐FDG PET/CT in patients with stage III non‐small cell lung cancer (NSCLC). We enrolled stage III NSCLC patients who had planned to receive definitive chemo‐radiation or radiotherapy (RT) and underwent 18F‐FDG PET/CT before treatment (PET1), during RT (at the fifth week, PET2) and after treatment (3 months later, PET3). By comparing with PET1, percentage changes of metabolic tumor volume (ΔMTV) and tumor total lesion glycolysis (ΔTLG) of PET2 and PET3 were calculated. We used medians of ΔTLG and ΔMTV as cut‐off values to stratify patients. Their prognostic values were evaluated by progression‐free survival (PFS) and overall survival (OS). Thirty patients were enrolled initially. Five were excluded due to multiple metastases or double cancer. The remaining 25 patients had PET2 at a median of 46 Gy. Data on PET3 were available in 19 patients. During‐RT ΔTLG (cut‐off: 65%) was a significant prognostic factor for PFS (P = 0.02) and OS (P < 0.01). During‐RT ΔMTV (cut‐off: 42%) had marginal significance for PFS (P = 0.07) and was significant for OS (P = 0.02). Of the PET3 parameters, neither ΔTLG nor ΔMTV was a significant prognostic factor for PFS and OS. We conclude that ΔTLG of during‐RT 18F‐FDG PET/CT may predict treatment response and thus provide opportunities to modify treatment for poor responders.

Prognostic Value of Early Fluorodeoxyglucose-Positron Emission Tomography Response Imaging and Peripheral Immunologic Biomarkers: Substudy of a Phase II Trial of Risk-Adaptive Chemoradiation for Unresectable Non-Small Cell Lung Cancer

“… 10 In our trial, being a PET responder versus nonresponder no longer conferred a difference in OS or PFS, perhaps due in part to our adaptive dose escalation in patients based on PET interval changes during chemoradiation, which may have mitigated the prognostic power of the PET response. However, in agreement with other published reports, 5 , 10 , 42 we found that midtreatment TLG was associated with OS and PFS, potentially serving as a marker of disease burden, even after adjustments for clinical and treatment factors. Patients classified as PET nonresponders on the midtreatment scan who also presented with a high residual TLG had the worst outcomes.…”

Relationship Between PET/CT Response and Survival in Patients with Non-Small-Cell Lung Cancer Treated with Definitive Chemoradiotherapy

“…28 Conversely, Chen et al evaluated 25 patients at week 5 during chemo-RT (at a median of 46 Gy) and 3rd month after chemo-RT and reported that TLG (cut-off 65%) and MTV (cut-off 42%) changes during RT resulted in significantly increased OS and PFS but these changes were not significant at 3rd month. 29 It has been shown that evaluation using PET/CT can led to a dose increase or treatment modification during the treatment and it has also been found to provide 3% benefit in terms of salvage therapy for patients who progress 3 months after the treatment. 12,30,31 Because RT causes inflammatory reactions in lung tissues, there is an ongoing discussion about the best time to evaluate response using PET/CT.…”

New developments in locally advanced nonsmall cell lung cancer

“…This seems to primarily be the case for the adenocarcinoma type of NSCLC [34]. The relevance of metabolic response to induction chemotherapy before surgery [35] and (chemo)radiotherapy [36] or the response (chemo)radiotherapy [37][38][39][40] is further evaluated. In addition, radiomic and artificial intelligence approaches are being pursued in this setting [41].…”