SDHA Germline Variants in Adult Patients With SDHA-Mutant Gastrointestinal Stromal Tumor

BackgroundSDH-deficient gastrointestinal stromal tumors (GIST) account for 20–40% of all KIT/PDGFRA-negative GIST and are due to mutations in one of the four SDH-complex subunits, with SDHA mutations as the most frequent. Here we sought to evaluate the presence and prevalence of SDHA variants in the germline lineage in a population of SDHA-deficient GIST.MethodsGermline SDHA status was assessed by Sanger sequencing on a series of 14 patients with gastric SDHA-deficient GIST.ResultsAll patients carried a germline SDHA pathogenic variant, ranging from truncating, missense, or splicing variants. The second hit was the loss of the wild-type allele or an additional somatic mutation. One-third of the patients were over 50 years old. GIST was the only disease presentation in all cases except one, with no personal or familial cancer history. Seven metastatic cases received a multimodal treatment integrating surgery, loco-regional and medical therapy. The mean follow-up time was of 10 years, confirming the indolent clinical course of the disease.ConclusionSDHA germline variants are highly frequent in SDHA-deficient GIST, and the disease may occur also in older adulthood. Genetic testing and surveillance of SDHA-mutation carriers and relatives should be performed.

Development and Evaluation of the Canteen Connect Online Health Community: Using a Participatory Design Approach in Meeting the Needs of Young People Impacted by Cancer

Adolescent and young adults (AYAs) impacted by their own or familial cancer require information and peer support throughout the cancer journey to ameliorate feelings of isolation. Online Health Communities (OHC) provide social networks, support, and health-related content to people united by a shared health experience. Using a participatory design (PD) process, Canteen developed Canteen Connect (CC), an OHC for AYAs impacted by cancer. This manuscript outlines the process used to develop CC: (1) A mixed-methods implementation evaluation of Version I of CC (CCv.1); (2) Qualitative workshops utilizing strengths-based approaches of PD and appreciative inquiry to inform the development of CC Version 2 (CCv.2); quantitative implementation evaluation to assess the appropriateness, acceptability, and effectiveness of CCv.2. Through several iterations designed and tested in collaboration with AYAs, CCv.2 had improvements in the user experience, such as the ability to send a private message to other users and the site becoming mobile responsive. Results from the evaluation showed CCv.2 was appropriate for connecting with other AYAs. Most AYAs reported satisfaction with CCv.2 and a positive impact on their feelings of sadness, worry, and/or anxiety. CCv.2 fills an important service provision gap in providing an appropriate and acceptable OHC for AYAs impacted by cancer, with initial promising psychological outcomes.

Gene Expression and Mutational Profile in BAP-1 Inactivated Melanocytic Lesions of Progressive Malignancy from a Patient with Multiple Lesions

BAP-1 (BRCA1-associated protein 1) inactivated melanocytic lesions are a group of familial or sporadic lesions with unique histology and molecular features. They are of great clinical interest, at least in part due to the potential for malignant transformation and association with a familial cancer predisposition syndrome. Here, we describe a patient with multiple spatially and temporally distinct melanocytic lesions with loss of BAP1 expression by immunohistochemistry. RNA sequencing was performed on three independent lesions spanning the morphologic spectrum: a benign nevus, an atypical tumor, and a melanoma arising from a pre-existing BAP1-inactivated nevus. The three lesions demonstrated largely distinct gene expression and mutational profiles. Gene expression analysis revealed that genes involved in receptor protein kinase pathways were progressively upregulated from nevus to melanoma. Moreover, a clear enrichment of genes regulated in response to UV radiation was found in the melanoma from this patient, as well as upregulation of MAPK pathway-related genes and several transcription factors related to melanomagenesis.

Cohort profile: the Spanish Early-onset Colorectal Cancer (SECOC) cohort: a multicentre cohort study on the molecular basis of colorectal cancer among young individuals in Spain

PurposeThe Spanish Early-onset Colorectal Cancer (SECOC) study is a multicentre prospective cohort established in Spain to investigate the molecular basis of early-onset colorectal cancer (EOCRC), including metabolic alterations.Participants220 patients with EOCRC have been enrolled since January 2019 through 18 centres across Spain. Individual-level data were collected by questionnaire, including lifestyle and other colorectal cancer-related factors. Medical record review was performed to capture clinical, histopathological and familial cancer history data. Biospecimen collection (blood, stool, tissue) at diagnosis and at various time points across treatment, as applicable, is also completed.Findings to dateParticipants had a median age of 44 years (range 14–49), and the majority are men (60%), with individuals age 40–49 years at EOCRC diagnosis being over-represented. Forty-three per cent of participants were diagnosed with a tumour in the rectosigmoid junction/rectum. Nearly two-thirds of EOCRC cases (64%) were diagnosed with advanced stage (III–IV) disease, and 28% of cases had no reported familial history of cancer.Future plansWe are actively recruiting and observing participants; we plan to administer follow-up questionnaires and perform additional biospecimen collection. This prospective cohort offers a unique, rich resource for research on EOCRC aetiologies and will contribute to larger international efforts to disentangle the rising disease burden.

Increased somatic mutation burdens in normal human cells due to defective DNA polymerases

Mutation accumulation in somatic cells contributes to cancer development and is proposed as a cause of aging. DNA polymerases Pol ε and Pol δ replicate DNA during cell division. However, in some cancers, defective proofreading due to acquired POLE/POLD1 exonuclease domain mutations causes markedly elevated somatic mutation burdens with distinctive mutational signatures. Germline POLE/POLD1 mutations cause familial cancer predisposition. Here, we sequenced normal tissue and tumor DNA from individuals with germline POLE/POLD1 mutations. Increased mutation burdens with characteristic mutational signatures were found in normal adult somatic cell types, during early embryogenesis and in sperm. Thus human physiology can tolerate ubiquitously elevated mutation burdens. Except for increased cancer risk, individuals with germline POLE/POLD1 mutations do not exhibit overt features of premature aging. These results do not support a model in which all features of aging are attributable to widespread cell malfunction directly resulting from somatic mutation burdens accrued during life.

Cis-Acting Factors Causing Secondary Epimutations: Impact on the Risk for Cancer and Other Diseases

Epigenetics affects gene expression and contributes to disease development by alterations known as epimutations. Hypermethylation that results in transcriptional silencing of tumor suppressor genes has been described in patients with hereditary cancers and without pathogenic variants in the coding region of cancer susceptibility genes. Although somatic promoter hypermethylation of these genes can occur in later stages of the carcinogenic process, constitutional methylation can be a crucial event during the first steps of tumorigenesis, accelerating tumor development. Primary epimutations originate independently of changes in the DNA sequence, while secondary epimutations are a consequence of a mutation in a cis or trans-acting factor. Secondary epimutations have a genetic basis in cis of the promoter regions of genes involved in familial cancers. This highlights epimutations as a novel carcinogenic mechanism whose contribution to human diseases is underestimated by the scarcity of the variants described. In this review, we provide an overview of secondary epimutations and present evidence of their impact on cancer. We propose the necessity for genetic screening of loci associated with secondary epimutations in familial cancer as part of prevention programs to improve molecular diagnosis, secondary prevention, and reduce the mortality of these diseases.

Germline Missense Variants in CDC20 Result in Aberrant Mitotic Progression and Familial Cancer

SUMMARYCDC20 is a co-activator of the anaphase promoting complex/cyclosome (APC/C) and is essential for mitotic progression. APC/CCDC20 is inhibited by the spindle assembly checkpoint (SAC), which prevents premature separation of sister chromatids and aneuploidy in daughter cells. Although overexpression of CDC20 is common in many cancers, oncogenic mutations have never been identified in humans. Using whole exome sequencing, we identified heterozygous missense CDC20 variants (L151R and N331K) that segregate with cancer in two families. Characterization of these mutants showed they retain APC/C activation activity but show reduced binding to BUBR1, a component of the SAC. Expression of L151R and N331K promoted mitotic slippage in HeLa cells and primary skin fibroblasts derived from carriers. CRISPR/Cas9 was used to generate mice carrying N331K. Homozygous mice carrying N331K were non-viable, however, heterozygotes displayed accelerated oncogenicity in Myc-driven cancers. These findings highlight an unappreciated role for CDC20 variants as tumor promoting genes in humans.

Retrospective Analysis of Clinicopathological Features and Familial Cancer History of Synchronous Bilateral Breast Cancer

Bilateral breast cancer is a strong predictor of BRCA 1/2 mutation and hence one criterion indicated for hereditary genetic testing. The purpose of this study is to assess the characteristics of synchronous bilateral breast cancer (SBBC) and its association with personal and familial cancer traits. Patients diagnosed with SBBC in our institute between 1992 and 2018 were retrospectively reviewed, and the information of clinicopathological features, personal and family cancer history were analyzed. Of the 307 SBBCs enrolled, the growing case number generally aligned with the regional breast cancer incidence after the era of population-based mammography screening. SBBC patients had similar cancer stages but worse survival outcomes than those in the standard scenario. A total of 42.0% had mixed pathological diagnoses, and 22.8% had discordant immunohistochemistry (IHC) subtypes from both sides, which contributed to treatment challenges. The correlation of SBBC with hereditary breast and ovarian cancer (HBOC) syndrome was strongly implied, as 20.7% of our SBBC patients with known familial cancer histories had HOBC-related familial cancers (breast, ovarian, or prostate cancers). These findings highlight the need for genetic counseling and germline mutation testing in patients with SBBC. Early PARP inhibitor treatment should also be considered in high-risk cases for outcome improvement.