Purpose: Cancer-associated fibroblasts (CAFs) expressing fibroblast activation protein (FAP) have been associated with the aggressive nature of head and neck cancers (HNCs). These tumours grow diffusely, leading to extremely challenging differentiation between tumour and healthy tissue. This analysis aims to introduce a novel approach of tumour detection, contouring and targeted radiotherapy of HNCs using visualisation of CAFs: PET-CT with ⁶⁸Ga-radiolabeled inhibitors of FAP (FAPI). Methods: FAPI PET-CT was performed without complications prior to radiotherapy in addition to contrast enhanced CT (CE-CT) and MRI on 14 patients with HNC. First, for tissue biodistribution analysis, volumes of interest were defined to quantify SUV_mean and SUV_max in tumour and healthy parenchyma. Secondly, using four thresholds of three-, five-, seven- and tenfold increase of FAPI enhancement in the tumour as compared with normal tissue, four different gross tumour volumes (FAPI-GTV) were created automatically. These were compared with GTVs created conventionally with CE-CT and MRI (CT-GTV). Results: The biodistribution analysis revealed high FAPI avidity within tumorous lesions (e.g. primary tumours, SUV_max 14.62 ± 4.44; SUV_mean 7.41 ± 2.39). In contrast, low background uptake was measured in healthy tissues of the head and neck region (e.g. salivary glands: SUV_max 1.76 ± 0.31; SUV_mean 1.23 ± 0.28). Considering radiation planning, CT-GTV was of 27.3 ml, whereas contouring with FAPI resulted in significantly different GTVs of 67.7 ml (FAPI × 3, p = 0.0134), 22.1 ml (FAPI × 5, p = 0.0419), 7.6 ml (FAPI × 7, p = 0.0001) and 2.3 ml (FAPI × 10, p = 0.0001). Taking these significant disparities between the GTVs into consideration, we merged FAPI-GTVs with CT-GTVs. This resulted in median volumes, that were, as compared to CT-GTVs, significantly larger with FAPI × 3 (54.7 ml, + 200.5% relative increase, p = 0.0005) and FAPI × 5 (15.0 ml, + 54.9%, p = 0.0122). Furthermore, FAPI-GTVs were not covered by CE-CT-based planning target volumes (CT-PTVs) in several cases. Conclusion: We present first evidence of diagnostic and therapeutic potential of FAPI ligands in head and neck cancer. Larger studies with histopathological correlation are required to validate our findings.

Long-term survival is rare in patients with glioblastoma (GBM). We set out to determine prognostic factors for patients with favorable and poor prognosis in regard of tumor localization to the subventricular zone (SZV). We reviewed the clinical records, pre-operative and post-operative MRI imaging of 50 LTS long-term survivors (LTS) (> 3 years) and 50 short-term survivors (STS) (< 1 year) with glioblastoma. These groups were matched for clinical characteristics being consistently associated with prolonged or shortened survival. All patients had undergone initial surgery or biopsy to confirm GBM diagnosis followed by radio- or chemoradiotherapy. LTS had a median progression-free survival PFS of 25, 4 months (2, 3-97, 8 months) and overall-survival (OS) of 55, 9 months (38, 2-98, 6 months) compared to STS who had a significantly lower PFS of 4, 2 months (1, 4-10, 2 months) and OS of 6, 6 months (2, 2-11, 6 months) (each p < 0,001).Survival analysis showed that age under 60 years (p < 0,001), total resection status (p < 0,001) and tumor localization without SVZ contact (p = 0,05) were significant factors for prolonged survival. Our findings underline that survival in GBM patients is heterogeneous and influenced by multiple factors. This study confirms that tumor location with regard to the SVZ is significantly associated with survival.

Background and purpose Low-grade glioma (LGG) is a very common brain tumor in pediatric patients typically associated with a very good prognosis. This prognosis makes it imperative that the risk of long-term treatment-related side effects be kept at an absolute minimum. Proton therapy (PRT) provides a radiation technique that has the potential to further reduce the genesis of radiogenic impairment. Materials and methods We retrospectively assessed 74 patients with LGG who underwent PRT. Conventional three-dimensional photon and PRT plans were generated after contouring structures of neurogenesis, crucial neuronal structures, and areas susceptible to secondary malignancies. Target volume coverage was evaluated using the homogeneity index (HI) and inhomogeneity coefficient (IC). Results were compared using the Wilcoxon-signed rank test, with p < 0.05 being statistically significant. Results Target volume coverage was comparable for the photon and proton plans. Overall, we could show an essential reduction in maximal, mean, and integral doses in critical neurologic structures, areas of neurogenesis, and structures of neurocognitive function. The study indicated specifically how contralaterally located structures could be spared with PRT. Conclusion PRT is a highly conformal radiation technique offering superior dosimetric advantages over conventional radiotherapy by allowing significant dose reduction for organs at risk (OAR) that are essential for neurologic function, neurocognition, and quality of life, thus demonstrating the potential of this technique for minimizing long-term sequelae.

Tumor radioresistance leading to local therapy failure remains a major obstacle for successful treatment of high-grade glioma. We hypothesized that distinct radiobiological features of particle therapy with carbon ions may circumvent glioma radioresistance. We demonstrate that carbon irradiation (CIR) efficiently eradicates radioresistant patient-derived glioma stem cells (GSCs), leading to growth inhibition and prolonged survival. The impact of CIR at the tumor–stroma interface was further investigated in 2 syngeneic mouse and 2 orthotopic GSC xenograft models. Intriguingly, tumor regressions and long-term local controls were observed at doses greater than or equal to 15-Gy CIR. Fractionated CIR further prolonged survival. The enhanced relative biological effectiveness of CIR in vivo was attributed to its potent antiangiogenic effects and eradication of radioresistant hypoxic tumor cells. Blockade of the HIF1-α/stromal cell–derived factor 1/CXCR4 axis by CIR reduced the recruitment of microglia and myeloid-derived suppressor cells (CD11b ⁺ Gr1 ⁺ ). Consequently, CIR abrogated M2-like immune polarization and enhanced the influx of CD8 ⁺ cells, generating an immunopermissive niche. We report that radiotherapy with carbon ions could surmount several central glioma resistance mechanisms by eradicating hypoxic and stem cell–like tumor cells, as well as modulating the glioma niche toward an antiangiogenic and less immunosuppressive state. Conclusively, potentially novel rationales for CIR in conquering glioma radioresistance are provided.

There are already numerous reports about high local control rates in patients with craniopharyngioma but there are only few studies with follow up times of more than 10 years. This study is an analysis of long term control, tumor response and side effects after fractionated stereotactic radiotherapy (FSRT) for patients with craniopharyngioma. 55 patients who were treated with FSRT for craniopharyngioma were analyzed. Median age was 37 years (range 6–70 years), among them eight children < 18 years. Radiotherapy (RT) was indicated for progressive disease after neurosurgical resection or postoperatively after repeated resection or partial resection. A median dose of 52.2 Gy (50 – 57.6 Gy) was applied with typical dose per fraction of 1.8 Gy five times per week. The regular follow up examinations comprised in addition to contrast enhanced MRI scans thorough physical examinations and clinical evaluation. During median follow up of 128 months (2 – 276 months) local control rate was 95.3% after 5 years, 92.1% after 10 years and 88.1% after 20 years. Overall survival after 10 years was 83.3% and after 20 years 67.8% whereby none of the deaths were directly attributed to craniopharyngioma. Overall treatment was tolerated well with almost no severe acute or chronic side effects. One patient developed complete anosmia, another one’s initially impaired vision deteriorated further. In 83.6% of the cases with radiological follow up a regression of irradiated tumor residues was monitored, in 7 cases complete response was achieved. 44 patients presented themselves initially with endocrinologic dysfunction none of them showed signs of further deterioration during follow up. No secondary malignancies were observed. Long term results for patients with craniopharyngioma after stereotactic radiotherapy are with respect to low treatment related side effects as well as to local control and overall survival excellent.

Primary adenoid cystic carcinomas (ACCs) of the trachea are rare tumors of the central bronchial system. In patients presenting with unresectable tumors, severe comorbidities, or incomplete surgical resection, definitive radiotherapy is currently the recommended treatment. Irradiation with carbon ions (C12) has shown promising local control (LC) and survival rates in cases of ACCs of the head and neck. No data on the therapeutic efficacy of C12 radiotherapy in treating tracheal ACC has been published. All patients with histologically confirmed ACC of the trachea treated with surgery and/or radiation treatment at Heidelberg University Hospital between 1991 and 2017 were included in this analysis. Patient and treatment characteristics, short- and long-term toxicity after radiotherapy, overall survival (OS), freedom from local progression (FFLP), and freedom from distant progression (FFDP) were prospectively acquired and retrospectively analyzed. Thirty-eight patients (23 women and 15 men) with a median age of 51 were treated by surgery (n = 20) and/or radiotherapy with either C12 (n = 7) or photons (n = 24). Of these patients, 61% presented with locally advanced (stage 4) ACC. The median follow-up for all patients was 74.5 months. The 5-year OS for all patients was 95% (10-year: 81%). The 5-year FFLP and FFDP were 96% (10-year: 83%) and 69% (10-year: 53%), respectively. In patients who underwent surgery alone, the 5-year OS was 100% (10-year: 80%). The 5-year FFLP and FFDP were 100% (10-year: 100%) and 80% (10-year: 60%), respectively. In patients who underwent radiotherapy alone, the 5-year OS was 100% (10-year: 83%). The 5-year FFLP and FFDP were 88% (10-year: 44%) and 67% (10-year: 34%), respectively. In patients who received multi-modal treatment including surgery and adjuvant radiotherapy, the 5-year OS was 84% (10-year: 84%). The 5-year FFLP was 100% (10-year: 100%) and the 5-year FFDP was 65% (10-year, 65%). The long-term prognosis is favorable if surgery is performed. In cases of an incomplete resection, good OS can still be achieved following adjuvant radiotherapy. For radiotherapy, irradiation with C12 shows promising first results. However, more data is needed to prove the long-term advantage of C12 over photons. The ethics committee of the Heidelberg University Hospital approved the retrospective data analysis (S-174/2019).