BACKGROUND The prevalence and spectrum of predisposing mutations among children and adolescents with cancer are largely unknown. Knowledge of such mutations may improve the understanding of tumorigenesis, direct patient care, and enable genetic counseling of patients and families. METHODS In 1120 patients younger than 20 years of age, we sequenced the whole genomes (in 595 patients), whole exomes (in 456), or both (in 69). We analyzed the DNA sequences of 565 genes, including 60 that have been associated with autosomal dominant cancer-predisposition syndromes, for the presence of germline mutations. The pathogenicity of the mutations was determined by a panel of medical experts with the use of cancer-specific and locus-specific genetic databases, the medical literature, computational predictions, and second hits identified in the tumor genome. The same approach was used to analyze data from 966 persons who did not have known cancer in the 1000 Genomes Project, and a similar approach was used to analyze data from an autism study (from 515 persons with autism and 208 persons without autism). RESULTS Mutations that were deemed to be pathogenic or probably pathogenic were identified in 95 patients with cancer (8.5%), as compared with 1.1% of the persons in the 1000 Genomes Project and 0.6% of the participants in the autism study. The most commonly mutated genes in the affected patients were TP53 (in 50 patients), APC (in 6), BRCA2 (in 6), NF1 (in 4), PMS2 (in 4), RB1 (in 3), and RUNX1 (in 3). A total of 18 additional patients had protein-truncating mutations in tumor-suppressor genes. Of the 58 patients with a predisposing mutation and available information on family history, 23 (40%) had a family history of cancer. CONCLUSIONS Germline mutations in cancer-predisposing genes were identified in 8.5% of the children and adolescents with cancer. Family history did not predict the presence of an underlying predisposition syndrome in most patients. (Funded by the American Lebanese Syrian Associated Charities and the National Cancer Institute.)

Genomic studies of pediatric cancer have primarily focused on specific tumor types or high-risk disease. Here, we used a three-platform sequencing approach, including whole genome (WGS), exome, and RNA sequencing, to examine tumor and germline genomes from 309 prospectively identified children with newly diagnosed (85%) or relapsed/refractory (15%) cancers, unselected for tumor type. Eighty-six percent of patients harbored diagnostic (53%), prognostic (57%), therapeutically-relevant (25%), and/or cancer predisposing (18%) variants. Inclusion of WGS enabled detection of activating gene fusions and enhancer hijacks (36% and 8% of tumors, respectively), small intragenic deletions (15% of tumors) and mutational signatures revealing of pathogenic variant effects. Evaluation of paired tumor-normal data revealed relevance to tumor development for 55% of pathogenic germline variants. This study demonstrates the power of a three-platform approach that incorporates WGS to interrogate and interpret the full range of genomic variants across newly diagnosed as well as relapsed/refractory pediatric cancers. STATEMENT OF SIGNIFICANCEPediatric cancers are driven by diverse genomic lesions and sequencing has proven useful in evaluating high risk and relapsed/refractory cases. We show that combined whole genome, exome, and RNA-sequencing of tumor and paired normal tissues enables identification and characterization of genetic drivers across the full spectrum of pediatric cancers.Research.

Background The incorporation of genomic testing to identify targetable somatic alterations and predisposing germline mutations into the clinical setting is becoming increasingly more common. Despite its potential utility, physician confidence in understanding and applying genomic testing remains unclear, particularly in the realm of pediatric oncology. Methods Before initiating an institutional feasibility study on the integration of clinical genomic testing, we surveyed pediatric oncologists regarding their confidence around understanding of genomic testing, perceived utility of test results, preferences around germline results disclosure, and possible risks and benefits of testing. Results Among survey respondents (52 of 88; response rate 59%), only a minority were confident in interpreting, utilizing, and discussing somatic (35%) or germline (27%) genomic test results. Providers confident in interpreting somatic results were significantly more likely to anticipate using the results to plan the treatment of refractory cancers (p = 0.009). Similarly, providers who reported confidence in interpreting germline results were significantly more likely to discuss and utilize these results as part of clinical care (p < 0.0001, respectively). The majority of physicians (93%), regardless of their levels of confidence, wanted to speak to a genetic counselor prior to disclosing germline results. Conclusions Among physicians at a comprehensive pediatric cancer center, confidence in the interpretation, utilization, and discussion of oncology-based genomic results is low, both in terms of somatic and germline testing. To optimize the integration of genomic sequencing into cancer care, methods must be developed to improve basic competencies around cancer-based genomic testing. Given the complexities surrounding variant interpretation and genotype-phenotype relationships, interdisciplinary collaborations are warranted.

Background Patients with cancer are increasingly offered genomic sequencing, including germline testing for cancer predisposition or other disorders. Such testing is unfamiliar to patients and families, and clear communication is needed to introduce genomic concepts and convey risk and benefit information. Methods Parents of children with cancer were offered the opportunity to have their children’s tumor and germline examined with clinical genomic sequencing. Families were introduced to the study with a 2‐visit informed consent model. Baseline genetic knowledge and self‐reported literacy/numeracy were collected before a study introduction visit, during which basic concepts related to genomic sequencing were discussed. Information was reinforced during a second visit, during which informed consent was obtained and a posttest was administered. Results As reflected by the percentage of correct answers on the pretest and posttest assessments, this model increased genetic knowledge by 11.1% (from 77.8% to 88.9%; P < .0001) in 121 parents participating in both the study introduction and consent visits. The percentage of parents correctly identifying the meaning of somatic and germline mutations increased significantly (from 18% to 59% [somatic] and from 31% to 64% [germline]; P < .0001). Nevertheless, these concepts remained unfamiliar to one‐third of the parents. No relation was identified between the change in the overall percentage of correct answers and self‐reported literacy, numeracy, or demographics. Conclusions The use of a 2‐visit communication model improved knowledge of concepts relevant to genomic sequencing, particularly differences between somatic and germline testing; however, these areas remained confusing to many participants, and reinforcement may be necessary to achieve complete understanding.

Patients harboring germline pathogenic biallelic variants in genes involved in the recognition and repair of DNA damage are known to have a substantially increased cancer risk. Emerging evidence suggests that individuals harboring heterozygous variants in these same genes may also be at heightened, albeit lesser, risk for cancer. Herein, we sought to determine whether heterozygous variants in RECQL4, the gene encoding an essential DNA helicase that is defective in children with the autosomal recessive cancer-predisposing condition Rothmund–Thomson syndrome (RTS), are associated with increased risk for childhood cancer. To address this question, we interrogated germline sequence data from 4435 pediatric cancer patients at St. Jude Children's Research Hospital and 1127 from the National Cancer Institute Therapeutically Applicable Research to Generate Effective Treatment (TARGET) database and identified 24 (0.43%) who harbored loss-of-function (LOF) RECQL4 variants, including five of 249 (2.0%) with osteosarcoma (OS). These RECQL4 variants were significantly overrepresented in children with OS, the cancer most frequently observed in patients with RTS, as compared to 134,187 noncancer controls in the Genome Aggregation Database (gnomAD v2.1; P = 0.00087, odds ratio [OR] = 7.1, 95% CI, 2.9–17). Nine of the 24 (38%) individuals possessed the same c.1573delT (p.Cys525Alafs) variant located in the highly conserved DNA helicase domain, suggesting that disruption of this domain is central to oncogenesis. Altogether these data expand our understanding of the genetic factors predisposing to childhood cancer and reveal a novel association between heterozygous RECQL4 LOF variants and development of pediatric OS.