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• Traditional clinical risk factors showed the strongest associations with survival. • Tumor volume was the most important image factor in univariate survival analysis. • FDG PET provided strong predictors only for HPV-unrelated head and neck cancer. Standardized uptake value (SUV) and related parameters derived from 2-deoxy-2-[18F]-fluoro- d -glucose (FDG) PET/CT prior to radiochemotherapy of head and neck cancer (HNC) were significantly associated with survival in a number of studies. The aim of this study was to validate these findings and to evaluate the prognostic role of PET parameters also including clinical factors and HPV status. We reviewed 166 HNC cases with a radiotherapy planning FDG PET/CT scan. All patients received radiotherapy, 68–70 Gy with or without concomitant cisplatin. Primary endpoint was disease-free survival (DFS). Twelve clinical factors, including HPV, performance status, stage and treatment parameters and ten PET/CT image parameters including gross tumor volume (GTV), metastatic lymph node volume, SUVmax, metabolic tumor volume (MTV) and total lesion glycolysis (TLG), were collected. Univariate and multivariate Cox regression analyses were employed. Of the 166 patients included, 48 had locoregional and 23 had metastatic recurrence. None of the FDG PET parameters were significant in the univariate analysis using DFS as endpoint. HPV status, ECOG status and GTV-U (primary tumor and lymph node volume from CT) were statistically significant (p < 0.01). Only in the subgroup of HPV-unrelated HNC (HPV negative oropharyngeal cancer [OPC] and non-OPC; n = 73), the multivariate model could be improved by including MTV (p < 0.001). DFS events were 29 (31%) in HPV-related and 53 (73%) in HPV-unrelated HNC. FDG PET parameters appear less important for overall prognostication of radiochemotherapy outcome for HNC. Still, the association between the FDG PET parameters and survival is strong for HNC not related to HPV. Tumor volume from CT is generally more closely related to outcome than parameters derived from FDG PET/CT. [ABSTRACT FROM AUTHOR]

FDG PET/CT is perceived as a valuable diagnostic tool in addition to the standard diagnostic workup for patients with isolated neck lymph nodes of squamous cell carcinoma of unknown primary (SCCUP). For patients with SCCUP intended for primary radiotherapy, we hypothesize that the previously reported FDG PET/CT detection rates are too high. From 2008 to 2015, 30 SCCUP patients were examined with FDG PET/CT. The objective of the FDG PET/CT examination was twofold: (1) improve the radiotherapy target definition, and (2) identify the primary cancer. Before the FDG PET/CT, the patients had been through a standard workup consisting of CT of the neck and chest, examination with flexible endoscopy with patient awake, panendoscopy and examination under general anesthesia, tonsillectomy and sometimes blind sampling biopsies, and MRI (floor of the mouth). All FDG PET/CTs were performed applying a flat table, head support and fixation mask as part of the radiotherapy treatment planning. Diagnostic CT with contrast was an integrated part of the PET/CT examination. Only 1/30 patients (cancer of the vallecula) had their primary cancer detected by FDG PET/CT. In addition, a non-biopsied patient with high uptake in the ipsilateral palatine tonsil was included, giving a detection rate of ≤7 % (95 % CI 2-21 %). In this retrospective study, we found that the FDG PET/CT detection rate of the primary for SCCUP patients is lower than previously reported. It is questionable whether FDG PET/CT is necessary for these patients when improved, advanced workup is available. [ABSTRACT FROM AUTHOR]

Background: For patients with recurrent or second primary disease, re-irradiation can be challenging due to overlap with previously irradiated volumes. Dose painting may be attractive for these patients, as the focus is on delivering maximal dose to areas of high tumor activity. Here, we compare dose painting by contours (DPBC) treatment plans based on 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) with conventional plans. Material and methods: We included 10 patients with recurrent or second primary head and neck cancer (HNC) eligible for re-irradiation. Our conventional re-irradiation regimen is hyperfractionated radiotherapy 1.5 Gy twice daily over 4 weeks, giving a total dose of 60 Gy. For DPBC, we defined two prescription volumes, PV33 and PV66, corresponding to 33 and 66% of the highest FDG uptake in the tumor. The clinical target volume (CTV) prescription dose was 60 Gy, PV33; 65–67 Gy and PV66; 70–73 Gy. The DPBC plan is to be given the first 20 fractions and the conventional plan the last 20 fractions. Dose to organs at risk (OARs) were compared for DPBC and conventional treatment. By summation of the initial curative plan and the re-irradiation plan, we also evaluated differences in dose to the 2 ccm hot spot (D2cc). Results: We achieved DPBC plans with adequate target coverage for all 10 patients. There were no significant differences in OAR doses between the standard plans and the DPBC plans (p=.7). Summation of the initial curative plan and the re-irradiation plan showed that the median D2cc increased from 130 Gy (range 113–132 Gy; conventional) to 140 Gy (range 115–145 Gy; DPBC). Conclusions: Our proposed DPBC could be straightforwardly implemented and all plans met the objectives. Re-irradiation of HNC with DPBC may increase tumor control without more side effects compared to conventional radiotherapy. [ABSTRACT FROM AUTHOR]