Patterns-of-failure guided biological target volume definition for head and neck cancer patients: FDG-PET and dosimetric analysis of dose escalation candidate subregions

• Published in: Radiotherapy and oncology Vol. 124; no. 2; pp. 248 - 255
• Main Authors: Mohamed, Abdallah S.R., Cardenas, Carlos E., Garden, Adam S., Awan, Musaddiq J., Rock, Crosby D., Westergaard, Sarah A., Brandon Gunn, G., Belal, Abdelaziz M., El-Gowily, Ahmed G., Lai, Stephen Y., Rosenthal, David I., Fuller, Clifton D., Aristophanous, Michalis
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.08.2017
• Subjects: Adult; Aged; Aged, 80 and over; Biological target volume; Dose escalation; Dose-Response Relationship, Radiation; FDG-PET; Female; Fluorodeoxyglucose F18; Head and neck cancer; Head and Neck Neoplasms - diagnostic imaging; Head and Neck Neoplasms - pathology; Head and Neck Neoplasms - radiotherapy; Humans; Male; Middle Aged; Neoplasm Recurrence, Local - diagnostic imaging; Neoplasm Recurrence, Local - pathology; Neoplasm Recurrence, Local - radiotherapy; Patterns of failure; Positron Emission Tomography Computed Tomography - methods; Positron-Emission Tomography - methods; Radiopharmaceuticals; Radiotherapy Planning, Computer-Assisted - methods; Tomography, X-Ray Computed - methods; Treatment Failure; Tumor Burden; FDG-PET; Head and neck cancer; Dose escalation; Biological target volume; Patterns of failure
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2017.07.017

To identify the radio-resistant subvolumes in pretreatment FDG-PET by mapping the spatial location of the origin of tumor recurrence after IMRT for head-and-neck squamous cell cancer to the pretreatment FDG-PET/CT. Patients with local/regional recurrence after IMRT with available FDG-PET/CT and post-failure CT were included. For each patient, both pre-therapy PET/CT and recurrence CT were co-registered with the planning CT (pCT). A 4-mm radius was added to the centroid of mapped recurrence growth target volumes (rGTV’s) to create recurrence nidus-volumes (NVs). The overlap between boost-tumor-volumes (BTV) representing different SUV thresholds/margins combinations and NVs was measured. Forty-seven patients were eligible. Forty-two (89.4%) had type A central high dose failure. Twenty-six (48%) of type A rGTVs were at the primary site and 28 (52%) were at the nodal site. The mean dose of type A rGTVs was 71Gy. BTV consisting of 50% of the maximum SUV plus 10mm margin was the best subvolume for dose boosting due to high coverage of primary site NVs (92.3%), low average relative volume to CTV1 (41%), and least average percent voxels outside CTV1 (19%). The majority of loco-regional recurrences originate in the regions of central-high-dose. When correlated with pretreatment FDG-PET, the majority of recurrences originated in an area that would be covered by additional 10mm margin on the volume of 50% of the maximum FDG uptake.