Impact of magnetic resonance-guided versus conventional radiotherapy workflows on organ at risk doses in stereotactic body radiotherapy for lymph node oligometastases.

Background and purpose: Magnetic resonance (MR)-linac delivery is expected to improve organ at risk (OAR) sparing. In this study, OAR doses were compared for online adaptive MR-linac treatments and conventional cone beam computed tomography (CBCT)-linac radiotherapy, taking into account differences in clinical workflows, especially longer session times for MR-linac delivery. Materials and methods: For 25 patients with pelvic/abdominal lymph node oligometastases, OAR doses were calculated for clinical pre-treatment and daily optimized 1.5 T MR-linac treatment plans (5 × 7 Gy) and compared with simulated CBCT-linac plans for the pre-treatment and online anatomical situation. Bowelbag and duodenum were re-contoured on MR-imaging acquired before, during and after each treatment session. OAR hard constraint violations, D0.5cc and D10cc values were evaluated, focusing on bowelbag and duodenum. Results: Overall, hard constraints for all OAR were violated less often in daily online MR-linac treatment plans compared with CBCT-linac: in 5% versus 22% of fractions, respectively. D0.5cc and D10cc values did not differ significantly. When taking treatment duration and intrafraction motion into account, estimated delivered doses to bowelbag and duodenum were lower with CBCT-linac if identical planning target volume (PTV) margins were used for both modalities. When reduced PTV margins were achievable with MR-linac treatment, bowelbag doses were lower compared with CBCT-linac. Conclusions: Compared with CBCT-linac treatments, the online adaptive MR-linac approach resulted in fewer hard planning constraint violations compared with single-plan CBCT-linac delivery. With respect to other bowelbag/duodenum dose-volume parameters, the longer duration of MR-linac treatment sessions negatively impacts the potential dosimetric benefit of daily adaptive treatment planning.

Simultaneous targeting of insulin-like growth factor-1 receptor and anaplastic lymphoma kinase in embryonal and alveolar rhabdomyosarcoma: a rational choice.

BACKGROUND: Rhabdomyosarcoma (RMS) is an aggressive soft tissue tumour mainly affecting children and adolescents. Since survival of high-risk patients remains poor, new treatment options are awaited. The aim of this study is to investigate anaplastic lymphoma kinase (ALK) and insulin-like growth factor-1 receptor (IGF-1R) as potential therapeutic targets in RMS. PATIENTS AND METHODS: One-hundred-and-twelve primary tumours (embryonal RMS (eRMS)86; alveolar RMS (aRMS)26) were collected. Expression of IGF-1R, ALK and downstream pathway proteins was evaluated by immunohistochemistry. The effect of ALK inhibitor NVP-TAE684 (Novartis), IGF-1R antibody R1507 (Roche) and combined treatment was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays in cell lines (aRMS Rh30, Rh41; eRMS Rh18, RD). RESULTS: IGF-1R and ALK expression was observed in 72% and 92% of aRMS and 61% and 39% of eRMS, respectively. Co-expression was observed in 68% of aRMS and 32% of eRMS. Nuclear IGF-1R expression was an adverse prognostic factor in eRMS (5-year survival 46.9 ± 18.7% versus 84.4 ± 5.9%, p=0.006). In vitro, R1507 showed diminished viability predominantly in Rh41. NVP-TAE684 showed diminished viability in Rh41 and Rh30, and to a lesser extent in Rh18 and RD. Simultaneous treatment revealed synergistic activity against Rh41 and Rh30. CONCLUSION: Co-expression of IGF-1R and ALK is detected in eRMS and particularly in aRMS. As combined inhibition reveals synergistic cytotoxic effects, this combination seems promising and needs further investigation.

Building the bridge between rhabdomyosarcoma in children, adolescents and young adults: the road ahead.

Rhabdomyosarcoma (RMS) is a rare type of soft tissue sarcoma that mainly affects children, but also occurs in adolescents and (young) adults (AYA). Despite dramatic survival improvements reported by international study groups in children over the past decades, the awareness of a dismal outcome for older patients with RMS has grown. In contrast to the world-wide organization of care for children with RMS, standard care in adults lags behind. A step forward in RMS management for patients of all ages is urgently needed. Both paediatric oncologists and medical oncologists are essential players in development of a concept of RMS care, but bringing two worlds together seems not so easy. This review provides an overview which highlights the similarities and differences in children and adults with RMS. Furthermore, it comes up with a novel concept to overcome the virtual gap between the treatment approach of children and AYA with RMS.

Anaplastic lymphoma kinase aberrations in rhabdomyosarcoma: clinical and prognostic implications.

PURPOSE: The aim of this study is to investigate anaplastic lymphoma kinase (ALK) protein expression and underlying genetic aberrations in rhabdomyosarcoma (RMS), with special attention to clinical and prognostic implications. PATIENTS AND METHODS: A total of 189 paraffin-embedded RMS tumor specimens from 145 patients were collected on tissue microarray. ALK protein expression was evaluated by immunohistochemistry. ALK gene (2p23) copy number and translocations were determined by in situ hybridization. cDNA sequencing of the receptor tyrosine kinase domain of the ALK gene was assessed in 43 samples. RESULTS: Strong cytoplasmic ALK protein expression was more frequently observed in alveolar RMS (ARMS) than in embryonal RMS (ERMS) (81% v 32%, respectively; P < .001). ALK gene copy number gain was detected in the vast majority of ARMS (88%), compared with 52% of ERMS (P < .001). ALK copy number correlated with protein expression in primary tumors (n = 107). We identified one point mutation (2%) and seven tumors harboring whole exon deletions (16%). In ERMS, specific ALK gain in the primary tumor correlated with metastatic disease (100% in metastatic disease v 29% in nonmetastatic disease; P = .004) and poor disease-specific survival (5-year disease-specific survival: 62% v 82% for nonspecific or no gain; P = .046). CONCLUSION: Because ALK aberrations on genomic and protein levels are frequently found in RMSs, in particular ARMS, and are associated with disease progression and outcome in ERMS, ALK may play a role in tumor biology and may provide a potential therapeutic target for these tumors. Future research should aim at the oncogenic role of ALK and the potential effect of ALK inhibitors in RMS.

[An infant with unexplained epilepsy]. / Een zuigeling met onbegrepen epilepsie: slachtoffer van münchhausen-by-proxysyndroom.

A 6-month-old male infant with an unremarkable past medical history was admitted to the emergency department in an epileptic state. The seizures were resistant to treatment with conventional drugs. The child was sedated, intubated and admitted to the intensive care department. Despite extensive investigations no underlying disease was found. The seizures persisted and the child was repeatedly admitted to the hospital. Four months after the first presentation, ventricular fibrillation occurred from which the child was successfully resuscitated. His stomach appeared to contain a disinfectant and a severe ethanol-intoxication was found, leading to the diagnosis "Munchausen syndrome by proxy". The incidence of this syndrome is underestimated. Recognition of this potentially fatal phenomenon is often difficult, resulting in a delay in diagnosis. Paediatricians and general practitioners should be aware of this syndrome in children presenting with an unusual disease or an unusual medical history reported by the parents or care providers.