The Predictive Value of Early Assessment After 1 Cycle of Induction Chemotherapy with ¹⁸F-FDG PET/CT and Diffusion-Weighted MRI for Response to Radical Chemoradiotherapy in Head and Neck Squamous Cell Carcinoma

Abstract

The objective of this study was to assess the predictive value of early assessment (after 1 cycle of induction chemotherapy [IC]) with 18 F-FDG PET/CT and diffusion-weighted (DW) MRI for subsequent response to radical chemoradiotherapy in locally advanced head and neck squamous cell carcinoma (HNSCC). Methods: Twenty patients with stage III-IVa HNSCC prospectively underwent 18 F-FDG PET/CT and DW MRI before and 2 wk after each cycle of IC (first cycle, IC1; second cycle, IC2). Response was assessed 3 mo after completion of chemoradiotherapy with clinical examination, MRI, and 18 F-FDG PET/CT. Patients with persistent disease were classed as nonresponders. Changes in functional and molecular imaging parameters after IC1 were compared between responders and nonresponders with the Mann-Whitney U test. The significance threshold was set at a P value of less than 0.05. Results: Responders showed a significantly greater reduction in metabolic tumor volume (P 5 0.03) and total lesion glycolysis (P 5 0.04) after IC1 than nonresponders. Responders also showed a tendency toward a larger but statistically nonsignificant increase in apparent diffusion coefficient after IC1. There was no significant difference in the changes from baseline between the IC1 and IC2 for all functional and molecular imaging parameters, indicating that most biologic response to IC measured by 18 F-FDG PET/CT and DW MRI was observed early after the first cycle of IC. Conclusion: Our preliminary data indicate that the 18 F-FDG PET/CT-derived metabolic tumor volume or total lesion glycolysis, acquired after IC1, are early predictive biomarkers for ultimate response to subsequent chemoradiotherapy. These early biomarkers enable identification of patients at risk of treatment failure at an early time point, permitting treatment individualization and consideration of alternative strategies such as radiotherapy dose escalation or surgery.

Response assessment after induction chemotherapy for head and neck squamous cell carcinoma: From physical examination to modern imaging techniques and beyond

“…62 In the previously mentioned study of Wong et al, 59 a trend was observed for a higher ADC on DW-MRI after 1 cycle of induction chemotherapy in responders compared with nonresponders of induction chemotherapy followed by concomitant chemoradiation. 59 Conventional DW-MRI cannot separate perfusion and true diffusion-related effect. Intravoxel incoherent motion (IVIM) imaging is characterized by 3 parameters: pure diffusion coefficient; microvascular volume fraction; and perfusion-related incoherent microcirculation.…”

“…Assessment by PET/CT and DW‐MRI after the first cycle of induction chemotherapy (docetaxel, cisplatin, and 5‐fluorouracil) in 20 patients with advanced‐stage HNSCC who received 2 cycles of induction chemotherapy followed by concomitant chemoradiation was reported by Wong et al Responders, defined as patients without persistent disease at response assessment at 3 months after completion of chemoradiation with MRI, PET/CT, and clinical examination, showed a significantly greater reduction in metabolic tumor volume and total glycolysis both measured for ROI with uptake of ≥40% of SUVmax and with SUV ≥3.5 …”

Long-term Results of a Pilot Study Comparing FLT-PET and FDG-PET in the Evaluation of Response to Treatment in Advanced Head and Neck and Esophageal Malignancies

“…The limited number of patients in this study, coupled with the generally favorable PET responses to induction chemotherapy, precluded our ability to detect a correlation between PET changes and long-term oncologic outcomes. In contrast, several prior studies showed that post-induction FDG-PET responses correlated with subsequent PET responses and PFS [28][29][30]. The utility of FLT-PET in assessing responses after induction chemotherapy in HNSCC has only been evaluated by a small number of studies.…”

Imaging biomarkers in oncology: Basics and application to MRI

“…These studies have shown that a common pattern is an increase in ADC mean to a varying extent with different therapies. This may occur within days of starting treatment; a higher change in ADC mean is also associated with a pathological good response …”