Use of 18F-FDG PET/CT Imaging for Radiotherapy Target Volume Delineation after Induction Chemotherapy and for Prognosis of Locally Advanced Squamous Cell Carcinoma of the Head and Neck.

Nemira Jurkienė,Elona Juozaitytė,Erika Korobeinikova,Evaldas Padervinskis,Ilona Kulakienė,Diana Adlienė,Severina Šedienė,Milda Rudžianskienė,Viktoras Rudžianskas,Evelina Jaselskė

doi:10.3390/medicina54060107

Abstract

Background and objectives: Induction chemotherapy (ICT) before definitive chemoradiation (CRT) gives high response rates in locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN). However, pre-ICT gross tumor volume (GTV) for radiotherapy (RT) planning is still recommended. As 18F-FDG PET/CT has an advantage of biological tumor information comparing to standard imaging methods, we aimed to evaluate the feasibility of 18F-FDG PET/CT-based post-ICT GTV delineation for RT planning in LA-SCCHN and to assess the prognostic value of PET parameters: maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). Methods: 47 LA-SCCHN patients were treated with 3 cycles of ICT (docetaxel, cisplatin, and 5-fluorouracil) followed by CRT (70 Gy in 35 fractions with weekly cisplatin). Pre- and post-ICT PET/CT examinations were acquired. Planning CT was co-registered with post-ICT PET/CT and RT target volumes were contoured according to post-ICT PET. Post-ICT percentage decrease of SUVmax, MTV and TLG in primary tumor and metastatic regional lymphnodes (LN) was counted. Loco-regional failure patterns, 3-year progression free (PFS) and overall survival (OS) were evaluated. Results: 3-year PFS and OS rates for study population were 67% and 61% respectively. 31.9% of patients progressed loco-regionally. All progress was localized in high-to-intermediate dose (60–70 Gy) RT volumes and none in low dose (50 Gy) volumes. Decrease of SUVmax ≥ 74% (p = 0.04), MTV ≥ 68% (p = 0.03), TLG ≥ 76% (p = 0.03) in primary tumor, and LN TLG decrease ≥ 74% (p = 0.03) were associated with PFS. Decrease of primary tumor SUVmax ≥ 74% (p = 0.04), MTV ≥ 69% (p = 0.03), TLG ≥ 74% (p = 0.02) and LN TLG ≥ 73% (p = 0.02) were prognostic factors for OS. Conclusions: According to our results, 18F-FDG PET/CT-based post-ICT GTV delineation is feasible strategy without negative impacts on loco-regional control and survival. Percentage decrease of metabolic PET parameters SUVmax, MTV and TLG has a prognostic value in LA-SCCHN.

Highlights

Despite the absence of definitive scientific evidence, induction chemotherapy (ICT) for locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN) is often used in clinicalMedicina 2018, 54, 107; doi:10.3390/medicina54060107 www.mdpi.com/journal/medicinaMedicina 2018, 54, 107 practice [1]
Several studies reported no benefit of ICT in terms of survival [2,3,4], it has a role in selected cases if there is likely to be a delay between diagnosis and starting definitive chemoradiotherapy (CRT) and in organ preservation strategies [5]
According to the survival data presented above, we suggest that 18F-FDG positron emission tomography (PET)/CT scan obtained after TPF-based ICT might be used for LA-SCCHN intensity modulated radiation therapy (IMRT) planning

Summary

Introduction

Despite the absence of definitive scientific evidence, induction chemotherapy (ICT) for locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN) is often used in clinicalMedicina 2018, 54, 107; doi:10.3390/medicina54060107 www.mdpi.com/journal/medicinaMedicina 2018, 54, 107 practice [1]. The potential advantages of using post-ICT imaging for target volume delineation include the reduction of GTV due to tumor shrinkage and the possibility to spare normal tissues. Induction chemotherapy (ICT) before definitive chemoradiation (CRT) gives high response rates in locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN). As 18 F-FDG PET/CT has an advantage of biological tumor information comparing to standard imaging methods, we aimed to evaluate the feasibility of 18 F-FDG PET/CT-based post-ICT GTV delineation for RT planning in LA-SCCHN and to assess the prognostic value of PET parameters: maximum standardized uptake value (SUVmax ), metabolic tumor volume (MTV) and total lesion glycolysis (TLG).

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Discussion

Conclusion