Torbjörn Backman

Intratumoral genome diversity parallels progression and predicts outcome in pediatric cancer

Genetic differences among neoplastic cells within the same tumour have been proposed to drive cancer progression and treatment failure. Whether data on intratumoral diversity can be used to predict clinical outcome remains unclear. We here address this issue by quantifying genetic intratumoral diversity in a set of chemotherapy-treated childhood tumours. By analysis of multiple tumour samples from seven patients we demonstrate intratumoral diversity in all patients analysed after chemotherapy, typically presenting as multiple clones within a single millimetre-sized tumour sample (microdiversity). We show that microdiversity often acts as the foundation for further genome evolution in metastases. In addition, we find that microdiversity predicts poor cancer-specific survival (60%; P=0.009), independent of other risk factors, in a cohort of 44 patients with chemotherapy-treated childhood kidney cancer. Survival was 100% for patients lacking microdiversity. Thus, intratumoral genetic diversity is common in childhood cancers after chemotherapy and may be an important factor behind treatment failure.

Neuroblastoma Patient-Derived Orthotopic Xenografts Retain Metastatic Patterns and Geno- and Phenotypes of Patient Tumours.

Neuroblastoma is a childhood tumour with heterogeneous characteristics and children with metastatic disease often have a poor outcome. Here we describe the establishment of neuroblastoma patient‐derived xenografts (PDXs) by orthotopic implantation of viably cryopreserved or fresh tumour explants of patients with high risk neuroblastoma into immunodeficient mice. In vivo tumour growth was monitored by magnetic resonance imaging and fluorodeoxyglucose–positron emission tomography. Neuroblastoma PDXs retained the undifferentiated histology and proliferative capacity of their corresponding patient tumours. The PDXs expressed neuroblastoma markers neural cell adhesion molecule, chromogranin A, synaptophysin and tyrosine hydroxylase. Whole genome genotyping array analyses demonstrated that PDXs retained patient‐specific chromosomal aberrations such as MYCN amplification, deletion of 1p and gain of chromosome 17q. Thus, neuroblastoma PDXs recapitulate the hallmarks of high‐risk neuroblastoma in patients. PDX‐derived cells were cultured in serum‐free medium where they formed free‐floating neurospheres, expressed neuroblastoma gene markers MYCN, CHGA, TH, SYP and NPY, and retained tumour‐initiating and metastatic capacity in vivo. PDXs showed much higher degree of infiltrative growth and distant metastasis as compared to neuroblastoma SK‐N‐BE(2)c cell line‐derived orthotopic tumours. Importantly, the PDXs presented with bone marrow involvement, a clinical feature of aggressive neuroblastoma. Thus, neuroblastoma PDXs serve as clinically relevant models for studying and targeting high‐risk metastatic neuroblastoma.

Neuroblastoma patient-derived orthotopic xenografts reflect the microenvironmental hallmarks of aggressive patient tumours

Treatment of high-risk childhood neuroblastoma is a clinical challenge which has been hampered by a lack of reliable neuroblastoma mouse models for preclinical drug testing. We have previously established invasive and metastasising patient-derived orthotopic xenografts (PDXs) from high-risk neuroblastomas that retained the genotypes and phenotypes of patient tumours. Given the important role of the tumour microenvironment in tumour progression, metastasis, and treatment responses, here we analysed the tumour microenvironment of five neuroblastoma PDXs in detail. The PDXs resembled their parent tumours and retained important stromal hallmarks of aggressive lesions including rich blood and lymphatic vascularisation, pericyte coverage, high numbers of cancer-associated fibroblasts, tumour-associated macrophages, and extracellular matrix components. Patient-derived tumour endothelial cells occasionally formed blood vessels in PDXs; however, tumour stroma was, overall, of murine origin. Lymphoid cells and lymphatic endothelial cells were found in athymic nude mice but not in NSG mice; thus, the choice of mouse strain dictates tumour microenvironmental components. The murine tumour microenvironment of orthotopic neuroblastoma PDXs reflects important hallmarks of aggressive and metastatic clinical neuroblastomas. Neuroblastoma PDXs are clinically relevant models for preclinical drug testing.

Continuous Double U-stitch Gastrostomy in Children.

BACKGROUND In children, a gastrostomy button was placed as the initial feeding tube, using laparoscopy and a modified surgical technique. The aim of this study was to test the hypothesis that a new surgical procedure developed at our institution would result in fewer postoperative complications. PATIENTS AND METHODS Sixty-two consecutive children with nutritional problems underwent a video-assisted gastrostomy operation (VAG). The technique requires the use of a 2 or 3 mm laparoscope optic and a 5 mm trocar placed at the exit site chosen for the gastrostomy. A continuous double U-stitch absorbable suture created a purse string suture around the gastrostoma on the stomach and fixated the stomach to the abdominal wall. For comparison, we used a control group of 68 children with nutritional problems operated on with our previously published VAG technique. After surgery, the children were followed up at one and six months and all complications were documented according to a protocol. RESULTS The two groups of children were comparable with regard to their demographic data. There were no serious intra-operative or postoperative intra-abdominal complications requiring reoperation. There was a significantly lower incidence of the minor complication of granuloma around the gastrostoma in the study group compared with the control group. CONCLUSION This variation of the surgical technique is simple and effective. It allows primary placement of a gastrostomy button that is functionally and cosmetically comparable to a gastrostomy tube surgically placed by other methods. In this study, the patients had fewer postoperative problems than the control group.

Complications of video-assisted gastrostomy in children with malignancies or neurological diseases

Aim: To test the hypothesis whether the administration of cytostatic drugs close to surgery in children with malignancies influences the rate of postoperative complications. Method: Included in the study were 27 children with malignancies and a control group of 27 neurologically impaired children. All the children had nutritional problems and underwent a video‐assisted gastrostomy (VAG) operation during the period 1997–2002. The children were postoperatively followed up. All complications were documented according to a protocol by a specially trained nurse and correlated to the time elapsed from completion of the last preoperative or the first postoperative cytostatic drug treatment. The complications in the two groups were compared. Results: The children with malignant diseases did not have more postoperative complications of the VAG than those having neurological defects. There was no correlation to complications regarding timing of the operation and administration of cytostatic drugs.

Complications of video-assisted gastrostomy in children with or without a ventriculoperitoneal shunt

The aim of the study was to test the hypothesis that the presence of a ventriculoperitoneal shunt (VPS) influences the frequency of postoperative complications after video-assisted gastrostomy (VAG) in children. When using a power of 80%, a critical value for significance of 5% and an assumed population-based standard deviation of 0.4, it will be required to have a sample size of at least 14 children to show that a difference of 0.6 is significant when using Student’s t test for paired samples. Thus, 15 consecutive children with VPSs were included in the present study. All the children had nutritional problems and underwent a VAG operation at a tertiary care university hospital. After the operation, the children were prospectively followed up. Specially trained nurses documented all complications according to a protocol. For the purpose of comparison, we had a control group of neurologically disabled children without VPSs, matched for age and operated with VAG. The children did not present with any serious postoperative intra-abdominal complications or central nervous system infection. There was no significant difference in the frequency of minor complications between the studied group and the control group. This study did not reveal that children with VPSs who undergo a VAG button placement are at high risk for infection and subsequent shunt malfunction. They did not have more postoperative problems than a matched control group of neurologically disabled children.

Robot-assisted radical cystoprostatectomy in a small child with rhabdomyosarcoma: a case report

We report the first case of a robot-assisted radical cystoprostatectomy in a 22-month-old boy with embryonal rhabdomyosarcoma in his urinary bladder. Treatment according to international protocol CWS-2002 P (Cooperative Weichteilsarkom Studie) was given prior to surgery. The da Vinci S Surgical System from Intuitive Surgical (Sunnyvale, CA, USA) was used to laparoscopically remove the urinary bladder and prostate radically. The surgical procedure performed and the postoperative course were uneventful. This technique is safe and feasible also in small children. It seems to have advantages over open surgery and no disadvantages. We recommend this technique for further use.

Outcomes of biliary atresia in the Nordic countries - a multicenter study of 158 patients during 2005-2016

BACKGROUND/PURPOSE Biliary atresia is the most common reason for newborn cholestasis and pediatric liver transplantation. Even after normalization of serum bilirubin after portoenterostomy, most patients require liver transplantation by adulthood due to expanding fibrosis. We addressed contemporary outcomes of biliary atresia in the Nordic countries. METHODS Data on center and patients characteristics, diagnostic practices, surgical treatment, adjuvant medical therapy after portoenterostomy, follow-up and outcomes were collected from all the Nordic centers involved with biliary atresia care during 2005-2016. RESULTS Of the 154 patients, 148 underwent portoenterostomy mostly by assigned surgical teams at median age of 64 (interquartile range 37-79) days, and 95 patients (64%) normalized their serum bilirubin concentration while living with native liver. Postoperative adjuvant medical therapy, including steroids, ursodeoxycholic acid and antibiotics was given to 137 (93%) patients. Clearance of jaundice associated with young age at surgery and favorable anatomic type of biliary atresia, whereas annual center caseload >3 patients and diagnostic protocol without routine liver biopsy predicted early performance of portoenterostomy. The cumulative 5-year native liver and overall survival estimate was 53% (95% CI 45-62) and 88% (95% CI 83-94), respectively. Portoenterostomy age <65days and annual center caseload >3 patients were predictive for long-term native liver survival, while normalization of serum bilirubin after portoenterostomy was the major predictor of both native liver and overall 5-year survival. CONCLUSIONS The outcomes of biliary atresia in the Nordic countries compared well with previous European studies. Further improvement should be pursued by active measures to reduce patient age at portoenterostomy. RETROSPECTIVE PROGNOSIS STUDY Level II.

Four evolutionary trajectories underlie genetic intratumoral variation in childhood cancer

A major challenge to personalized oncology is that driver mutations vary among cancer cells inhabiting the same tumor. Whether this reflects principally disparate patterns of Darwinian evolution in different tumor regions has remained unexplored1–5. We mapped the prevalence of genetically distinct clones over 250 regions in 54 childhood cancers. This showed that primary tumors can simultaneously follow up to four evolutionary trajectories over different anatomic areas. The most common pattern consists of subclones with very few mutations confined to a single tumor region. The second most common is a stable coexistence, over vast areas, of clones characterized by changes in chromosome numbers. This is contrasted by a third, less frequent, pattern where a clone with driver mutations or structural chromosome rearrangements emerges through a clonal sweep to dominate an anatomical region. The fourth and rarest pattern is the local emergence of a myriad of clones with TP53 inactivation. Death from disease was limited to tumors exhibiting the two last, most dynamic patterns.Multiregional analysis in 54 childhood cancers highlights four evolutionary patterns of intratumoral variation. Multiple patterns are often found in the same tumor, suggesting that tumors follow different evolutionary strategies concurrently.

Pre- and Postoperative Vomiting in Children Undergoing Video-Assisted Gastrostomy Tube Placement

Background. The aim of this study was to determine the incidence of pre- and postoperative vomiting in children undergoing a Video-Assisted Gastrostomy (VAG) operation. Patients and Methods. 180 children underwent a VAG operation and were subdivided into groups based on their underlying diagnosis. An anamnesis with respect to vomiting was taken from each of the childrens parents before the operation. After the VAG operation, all patients were followed prospectively at one and six months after surgery. All complications including vomiting were documented according to a standardized protocol. Results. Vomiting occurred preoperatively in 51 children (28%). One month after surgery the incidence was 43 (24%) in the same group of children and six months after it was found in 40 (22%). There was a difference in vomiting frequency both pre- and postoperatively between the children in the groups with different diagnoses included in the study. No difference was noted in pre- and postoperative vomiting frequency within each specific diagnosis group. Conclusion. The preoperative vomiting symptoms persisted after the VAG operation. Neurologically impaired children had a higher incidence of vomiting than patients with other diagnoses, a well-known fact, probably due to their underlying diagnosis and not the VAG operation. This information is useful in preoperative counselling.