Pushing the Frontiers of Cancer Research: Highlights from the Frontiers in Cancer Science Conference 2023.

The 15th annual Frontiers in Cancer Science (FCS) conference gathered scientific experts who shared the latest research converging upon several themes of cancer biology. These themes included the dysregulation of metabolism, cell death, and other signaling processes in cancer cells; using patient "omics" datasets and single-cell and spatial approaches to investigate heterogeneity, understand therapy resistance, and identify targets; innovative strategies for inhibiting tumors, including rational drug combinations and improved drug delivery mechanisms; and advances in models that can facilitate screening for cancer vulnerabilities and drug testing. We hope the insights from this meeting will stimulate further progress in the field.

Cascade testing for hereditary cancer in Singapore: how population genomics help guide clinical policy.

Hereditary Cancer makes up around 5-10% of all cancers. It is important to diagnose hereditary cancer in a timely fashion, as not only do patients require long-term care from a young age, but their relatives also require management. The main approach to capture at-risk relatives is cascade testing. It involves genetic testing of relatives of the first detected carrier of a pathogenic variant in a family i.e. the proband. The current standard of care for cascade testing is a patient-mediated approach. Probands are then advised to inform and encourage family members to undergo genetic testing. In Singapore, cascade testing is inefficient, around 10-15%, lower than the 30% global average. Here, we describe the cascade testing process and its effort to increase testing in Singapore. Precision Health Research, Singapore (PRECISE), was set up to coordinate Singapore's National Precision Medicine strategy and has awarded five clinical implementation pilots, with one of them seeking to identify strategies for how cascade testing for hereditary cancer can be increased in a safe and cost-efficient manner. Achieving this will be done through addressing barriers such as cost, manpower shortages, exploring a digital channel for contacting at-risk relatives, and getting a deeper insight into why genetic testing gets declined. If successful, it will likely result in care pathways that are a cost-effective public health intervention for identifying individuals at risk. Surveillance and management of those unaffected at-risk individuals, if caught early, will result in improved patient outcomes, and further reduce the healthcare burden for the economy.

Strategies to improve implementation of cascade testing in hereditary cancer syndromes: a systematic review.

Hereditary cancer syndromes constitute approximately 10% of all cancers. Cascade testing involves testing of at-risk relatives to determine if they carry the familial pathogenic variant. Despite growing efforts targeted at improving cascade testing uptake, current literature continues to reflect poor rates of uptake, typically below 30%. This study aims to systematically review current literature on intervention strategies to improve cascade testing, assess the quality of intervention descriptions and evaluate the implementation outcomes of listed interventions. We searched major databases using keywords and subject heading of "cascade testing". Interventions proposed in each study were classified according to the Effective Practice and Organization of Care (EPOC) taxonomy. Quality of intervention description was assessed using the TIDieR checklist, and evaluation of implementation outcomes was performed using Proctor's Implementation Outcomes Framework. Improvements in rates of genetic testing uptake was seen in interventions across the different EPOC taxonomy strategies. The average TIDieR score was 7.3 out of 12. Items least reported include modifications (18.5%), plans to assess fidelity/adherence (7.4%) and actual assessment of fidelity/adherence (7.4%). An average of 2.9 out of 8 aspects of implementation outcomes were examined. The most poorly reported outcomes were cost, fidelity and sustainability, with only 3.7% of studies reporting them. Most interventions have demonstrated success in improving cascade testing uptake. Uptake of cascade testing was highest with delivery arrangement (68%). However, the quality of description of interventions and assessment of implementation outcomes are often suboptimal, hindering their replication and implementation downstream. Therefore, further adoption of standardized guidelines in reporting of interventions and formal assessment of implementation outcomes may help promote translation of these interventions into routine practice.

A Systematic Review of Diagnostic Modalities and Strategies for the Assessment of Complications in Adult Patients with Neurofibromatosis Type 1.

BACKGROUND: Neurofibromatosis Type 1 is an autosomal dominant tumour-predisposition condition commonly diagnosed in childhood and fully penetrant by adulthood. Long-term monitoring through imaging is inconsistent and varies between high- and low-income countries. Implementation of a clinical practice guideline through a multidisciplinary clinic is instrumental to the care of adult Neurofibromatosis Type 1 patients. We aim to systematically review international diagnostic modalities and strategies to evaluate any association between a country's socioeconomic status and diagnostic modalities or strategies used for Neurofibromatosis Type 1 patients. METHODS: We searched PubMed, Embase, Web of Science, and Cochrane. Relevant clinical information on the surveillance of adult Neurofibromatosis Type 1 patients worldwide was reviewed, extracted, and synthesised. RESULTS: We identified 51 papers reporting on 7724 individuals. Multiple imaging modalities are actively employed in high-income and upper-middle-income countries for surveying adult Neurofibromatosis Type 1 patients. We did not find any relevant papers from low- and middle-income countries. CONCLUSIONS: This systematic review suggests that there is robust data on diagnostic modalities for adult Neurofibromatosis Type 1 patients in high-income countries, but not for low- and middle-income countries. There is a lack of data on consolidated diagnostic strategies from both high- and low-income countries. Efforts should be made to publish data on usual clinical practice in low- and middle-income countries to develop clinical practice guidelines describing best medical practice to fit a local context.

First ever characterisation of the effects of short telomeres in a Singapore interstitial lung disease cohort.

BACKGROUND: Differences in disease behaviour and genotypes are described in Asian and Western interstitial lung disease (ILD) cohorts. Short leukocyte telomere length (LTL) correlates with poor outcomes in Western ILD cohorts but its significance in Asian populations is unknown. We aim to characterise the burden and clinical implications of short LTL in Singaporean ILD patients. METHODS: Patients diagnosed with ILD at Singapore General Hospital were prospectively recruited and compared against 36 healthy controls. The primary outcome was transplant-free survival. Genomic DNA from peripheral blood was extracted and LTL measured using quantitative polymerase chain reaction assay (qPCR). RESULTS: Amongst 165 patients, 37% had short LTL. There was a higher proportion of combined pulmonary fibrosis and emphysema (CPFE) patients with short LTL (n = 21, 34.4% vs n = 16, 15.4%; p < 0.001). Short LTL patients had reduced survival at 12-, 24- and 36-months and median survival of 24 months (p < 0.001) which remained significant following adjustment for smoking, GAP Stage and radiological UIP pattern (Hazard Ratio (HR), 2.74; 95%CI:1.46, 5.11; p = 0.002). They had increased respiratory-related mortality and acute exacerbation incidences. Despite similar baseline lung function, short LTL patients had a faster decline in absolute forced vital capacity (FVC) of -105.3 (95% CI: 151.4, -59.1) mL/year compared to -58.2 (95% CI: 82.9, -33.6) mL/year (p < 0.001) in normal LTL patients. CONCLUSION: Short LTL correlated with increased mortality and faster lung function decline in our Singaporean ILD cohort with a magnitude similar to that in Western ILD cohorts. Further research is needed to integrate LTL assessment into clinical practice.

Beyond a vestigial organ: effects of the appendix on gut microbiome and colorectal cancer.

The role of appendectomy in the pathogenesis of colorectal cancer (CRC) is a recent topic of contention. Given that appendectomy remains one of the most commonly performed operations and a first-line management strategy of acute appendicitis, it is inherently crucial to elucidate the association between prior appendectomy and subsequent development of CRC, as there may be long-term health repercussions. In this review, we summarize the data behind the relationship of CRC in post-appendectomy patients, discuss the role of the microbiome in relation to appendectomy and CRC pathogenesis, and provide an appraisal of our current understanding of the function of the appendix. We seek to piece together the current landscape surrounding the microbiome and immunological changes in the colon post-appendectomy and suggest a direction for future research involving molecular, transcriptomic, and immunologic analysis to complement our current understanding of the alterations in gut microbiome.

Age-specific breast and ovarian cancer risks associated with germline BRCA1 or BRCA2 pathogenic variants - an Asian study of 572 families.

Background: Clinical management of Asian BRCA1 and BRCA2 pathogenic variants (PV) carriers remains challenging due to imprecise age-specific breast (BC) and ovarian cancer (OC) risks estimates. We aimed to refine these estimates using six multi-ethnic studies in Asia. Methods: Data were collected on 271 BRCA1 and 301 BRCA2 families from Malaysia and Singapore, ascertained through population/hospital-based case-series (88%) and genetic clinics (12%). Age-specific cancer risks were estimated using a modified segregation analysis method, adjusted for ascertainment. Findings: BC and OC relative risks (RRs) varied across age groups for both BRCA1 and BRCA2. The age-specific RR estimates were similar across ethnicities and country of residence. For BRCA1 carriers of Malay, Indian and Chinese ancestry born between 1950 and 1959 in Malaysia, the cumulative risk (95% CI) of BC by age 80 was 40% (36%-44%), 49% (44%-53%) and 55% (51%-60%), respectively. The corresponding estimates for BRCA2 were 29% (26-32%), 36% (33%-40%) and 42% (38%-45%). The corresponding cumulative BC risks for Singapore residents from the same birth cohort, where the underlying population cancer incidences are higher compared to Malaysia, were higher, varying by ancestry group between 57 and 61% for BRCA1, and between 43 and 47% for BRCA2 carriers. The cumulative risk of OC by age 80 was 31% (27-36%) for BRCA1 and 12% (10%-15%) for BRCA2 carriers in Malaysia born between 1950 and 1959; and 42% (34-50%) for BRCA1 and 20% (14-27%) for BRCA2 carriers of the same birth cohort in Singapore. There was evidence of increased BC and OC risks for women from >1960 birth cohorts (p-value = 3.6 × 10-5 for BRCA1 and 0.018 for BRCA2). Interpretation: The absolute age-specific cancer risks of Asian carriers vary depending on the underlying population-specific cancer incidences, and hence should be customised to allow for more accurate cancer risk management. Funding: Wellcome Trust [grant no: v203477/Z/16/Z]; CRUK (PPRPGM-Nov20∖100002).

Single-cell landscape of idiopathic multicentric Castleman disease in identical twins.

ABSTRACT: Idiopathic multicentric Castleman disease (iMCD) is a rare cytokine-driven disorder characterized by systemic inflammation, generalized lymphadenopathy, and organ dysfunction. Here, we present an unusual occurrence of iMCD in identical twins and examined the immune milieu within the affected lymphoid organs and the host circulation using multiomic high-dimensional profiling. Using spatial enhanced resolution omics sequencing (Stereo-seq) transcriptomic profiling, we performed unsupervised spatially constrained clustering to identify different anatomic structures, mapping the follicles and interfollicular regions. After a cell segmentation approach, interleukin 6 (IL-6) pathway genes significantly colocalized with endothelial cells and fibroblastic reticular cells, confirming observations using a single-cell sequencing approach (10× Chromium). Furthermore, single-cell sequencing of peripheral blood mononuclear cells revealed an "inflammatory" peripheral monocytosis enriched for the expression of S100A family genes in both twins. In summary, we provided evidence of the putative cell-of-origin of IL-6 signals in iMCD and described a distinct monocytic host immune response phenotype through a unique identical twin model.

Using the Actor-Partner Interdependence Model to explore the psychological impact of COVID-19 on anxiety in dyads of patients with cancer and caregivers.

BACKGROUND: Delineating the compound psychological effect of the pandemic on cancer care, and the interdependency across cancer patient-caregiver dyads have yet to be explored. This study examines the levels of psychological impact of COVID-19 on patient-caregiver dyads anxiety, and the interdependent associations between their COVID-19 and cancer concerns, and risk perceptions. METHOD: There were 352 patients and caregivers (patient-caregiver dyads, N = 176) included in this study (43.2% spousal dyads). Generalized Anxiety Disorder-7 and questionnaires regarding risk perception, perceived confidence in healthcare system, COVID-19, and cancer-related concerns were administered. Actor-Partner Interdependence Model (APIM) analyses were used to determine the interdependent effects. Indirect effects were tested using mediation pathway analyses. RESULTS: Patients reported significantly higher levels of risk perceptions and anxiety than their caregivers (p < 0.01). Anxiety rates (GAD-7 ≥ 10) were also significantly higher (26.7% vs 18.2%, p < 0.01). Dyads' anxiety, "general COVID-19 concerns," "cancer-related concerns," and risk perceptions were correlated (ps < 0.01). APIM showed only actor effects of general COVID-19 concerns, cancer-related COVID-19 concerns, and risk perceptions on anxiety (ßs = 0.19-0.53, ps < 0.01). No partner effects were observed. Similar results were found in the composite APIM. Indirect effects of the patient/caregiver's variables on their partner's anxiety were observed in the mediation analyses. CONCLUSION: Concerns about COVID-19 and cancer care could be indirectly associated in patient-caregiver dyads and need to be proactively addressed. As pandemic evolves into endemicity, engagement with patients and caregivers should strive to be sensitive to their differential needs and messages should be tailored to the informational needs of each.

Cancer patients' experience of receiving variant of uncertain significance results: An Asian perspective.

Due to a lack of ancestry-matched, functional, and segregation data, Asians have a higher rate of receiving a variant of uncertain significance (VUS) result following panel testing. Managing VUS results presents challenges, as it often leads to increased anxiety and distress among cancer patients undergoing genetic testing. This exploratory study aims to investigate the experience of Asian cancer patients upon receiving a VUS result. A qualitative, semi-structured interview study was conducted, involving cancer patients who had received a VUS result through the Cancer Genetics Service of the National Cancer Centre Singapore. Twenty participants were interviewed, and their responses were transcribed and analyzed using thematic analysis to identify key themes. Thematic analysis revealed five major themes: (1) VUS results are interpreted as uncertain outcomes; (2) a VUS result provides relief and prompts positive behavioral adjustments; (3) patients employ fatalism and religion as coping mechanisms to navigate uncertainty; (4) genetic counselors, family, and the community offer reassurance and support; (5) patients value updates on variant classifications for future management. While this novel study provides unique insights into the perspectives of Asian patients who receive VUS results, it also highlights patients' effective management of VUS results and uncertainty, which has implications for improving counseling practices in Asia. Emphasis must be placed on accurate interpretation and clear communication of VUS results to dispel the possibility of misconceptions, misdiagnosis, and mismanagement in cancer care.

Clinical presentations and outcomes of young women aged <40 yrs with Ductal carcinoma in situ.

INTRODUCTION: Ductal carcinoma in situ (DCIS) in young women is rare and not well studied. Since they do not qualify for mammographic screening, they are more likely to present with symptoms. Young women have also been associated with poorer outcomes, but it is unknown whether presentation mode affects outcome. We aimed to compare characteristics of DCIS patients <40 years of age presenting with symptoms versus those without, and determine whether presentation mode affects recurrence. METHODS: Pure DCIS patients aged <40 years were retrospectively analyzed. Clinical presentation, pathology and recurrence data were collected. Statistical analysis was performed to investigate the correlation of presentation mode with outcomes. RESULTS: 40 patients with 41 cases were included. The mean age at diagnosis was 32.3 years (range 17-39). 73.2% and 26.8% presented with symptoms or abnormal imaging respectively. Of the cases who presented with symptoms, 86.7%, 10.0% and 3.3% had palpable lump, nipple discharge or breast pain, respectively. The average tumor size was 22.0 mm (range 2.0-86.9) and 12.2 mm (range 3-25) for patients who presented with symptoms and non-symptomatic group, respectively. Cases presenting with symptoms were statistically associated with higher grade (p = 0.0090). On median follow-up of 85 months, there were 3 (7.3%) recurrences, which were not statistically associated with presentation mode. CONCLUSION: Young women with DCIS tend to present with symptoms, with breast lump as the commonest symptom. Symptomatic patients tend to be associated with grade III tumours, compared to non-symptomatic patients. On long-term follow-up, mode of presentation was not statistically associated with recurrence.

Management of individuals with germline pathogenic/likely pathogenic variants in CHEK2: A clinical practice resource of the American College of Medical Genetics and Genomics (ACMG).

PURPOSE: Although the role of CHEK2 germline pathogenic variants in cancer predisposition is well known, resources for managing CHEK2 heterozygotes in clinical practice are limited. METHODS: An international workgroup developed guidance on clinical management of CHEK2 heterozygotes informed by peer-reviewed publications from PubMed. RESULTS: Although CHEK2 is considered a moderate penetrance gene, cancer risks may be considered as a continuous variable, which are influenced by family history and other modifiers. Consequently, early cancer detection and prevention for CHEK2 heterozygotes should be guided by personalized risk estimates. Such estimates may result in both downgrading lifetime breast cancer risks to those similar to the general population or upgrading lifetime risk to a level at which CHEK2 heterozygotes are offered high-risk breast surveillance according to country-specific guidelines. Risk-reducing mastectomy should be guided by personalized risk estimates and shared decision making. Colorectal and prostate cancer surveillance should be considered based on assessment of family history. For CHEK2 heterozygotes who develop cancer, no specific targeted medical treatment is recommended at this time. CONCLUSION: Systematic prospective data collection is needed to establish the spectrum of CHEK2-associated cancer risks and to determine yet-unanswered questions, such as the outcomes of surveillance, response to cancer treatment, and survival after cancer diagnosis.

Geographical, ethnic, and genetic differences in pancreatic cancer predisposition.

Pancreatic cancer remains a leading cause of cancer-related mortality worldwide. Treatment outcomes remain largely dismal despite significant medical advancements. This lends urgency to the need to understand its risk factors in order to guide early detection and improve outcomes. There are both modifiable and non-modifiable risk factors, the more established of such being that of age, smoking, obesity, diabetes mellitus (DM), alcohol and certain genetic predisposition syndromes with underlying germline mutations. Some genetic predisposition syndromes such as BRCA1/2, PALB2, ATM, and CDKN2A are well-established, arising from germline mutations that result in carcinogenesis through mechanisms such as cell injury, dysregulation of cell growth, dysfunctional DNA repair, and disruption of cell mobility and adhesion. There is also a significant proportion of familial pancreatic cancer (FPC) for which the underlying predisposing genetic mechanism is not yet understood. Nuances have emerged in the ethnic and geographical differences of pancreatic cancer predisposition, and these may be attributed to differences in lifestyle, standard of living, socioeconomic factors, and genetics. This review describes in detail the factors contributing to pancreatic cancer with focus on ethnic and geographical differences and hereditary genetic syndromes. Greater insight into the interplay of these factors can guide clinicians and healthcare authorities in addressing modifiable risk factors, implementing measures for early detection in high-risk individuals, initiating early treatment of pancreatic cancer, and directing future research towards existing knowledge deficits, in order to improve survival outcomes.

Investigating causal relationships between obesity and skin barrier function in a multi-ethnic Asian general population cohort.

BACKGROUND: Skin diseases impact significantly on the quality of life and psychology of patients. Obesity has been observed as a risk factor for skin diseases. Skin epidermal barrier dysfunctions are typical manifestations across several dermatological disturbances. OBJECTIVES: We aim to establish the association between obesity and skin physiology measurements and investigate whether obesity may play a possible causal role on skin barrier dysfunction. METHODS: We investigated the relationship of obesity with skin physiology measurements, namely transepidermal water loss (TEWL), skin surface moisture and skin pH in an Asian population cohort (n = 9990). To assess for a possible causal association between body mass index (BMI) and skin physiology measurements, we performed Mendelian Randomization (MR), along with subsequent additional analyses to assess the potential causal impact of known socioeconomic and comorbidities of obesity on TEWL. RESULTS: Every 1 kg/m2 increase in BMI was associated with a 0.221% (95%CI: 0.144-0.298) increase in TEWL (P = 2.82E-08), a 0.336% (95%CI: 0.148-0.524) decrease in skin moisture (P = 4.66E-04) and a 0.184% (95%CI: 0.144-0.224) decrease in pH (P = 1.36E-19), adjusting for age, gender, and ethnicity. Relationships for both TEWL and pH with BMI remained strong (Beta 0.354; 95%CI: 0.189-0.520 and Beta -0.170; 95%CI: -0.253 to -0.087, respectively) even after adjusting for known confounders, with MR experiments further supporting BMI's possible causal relationship with TEWL. Based on additional MR performed, none of the socioeconomic and comorbidities of obesity investigated are likely to have possible causal relationships with TEWL. CONCLUSION: We establish strong association of BMI with TEWL and skin pH, with MR results suggestive of a possible causal relationship of obesity with TEWL. It emphasizes the potential impact of obesity on skin barrier function and therefore opportunity for primary prevention.

Adiposity impacts cognitive function in Asian populations: an epidemiological and Mendelian Randomization study.

Background: Obesity and related metabolic disturbances including diabetes, hypertension and hyperlipidemia predict future cognitive decline. Asia has a high prevalence of both obesity and metabolic disease, potentially amplifying the future burden of dementia in the region. We aimed to investigate the impact of adiposity and metabolic risk on cognitive function in Asian populations, using an epidemiological analysis and a two-sample Mendelian Randomization (MR) study. Methods: The Health for Life in Singapore (HELIOS) Study is a population-based cohort of South-East-Asian men and women in Singapore, aged 30-84 years. We analyzed 8769 participants with metabolic and cognitive data collected between 2018 and 2021. Whole-body fat mass was quantified with Dual X-Ray Absorptiometry (DEXA). Cognition was assessed using a computerized cognitive battery. An index of general cognition ' g ' was derived through factor analysis. We tested the relationship of fat mass indices and metabolic measures with ' g ' using regression approaches. We then performed inverse-variance-weighted MR of adiposity and metabolic risk factors on ' g ', using summary statistics for genome-wide association studies of BMI, visceral adipose tissue (VAT), waist-hip-ratio (WHR), blood pressure, HDL cholesterol, triglycerides, fasting glucose, HbA1c, and general cognition. Findings: Participants were 58.9% female, and aged 51.4 (11.3) years. In univariate analysis, all 29 adiposity and metabolic measures assessed were associated with ' g ' at P < 0.05. In multivariable analyses, reduced ' g ' was consistently associated with increased visceral fat mass index and lower HDL cholesterol (P < 0.001), but not with blood pressure, triglycerides, or glycemic indices. The reduction in ' g ' associated with 1SD higher visceral fat, or 1SD lower HDL cholesterol, was equivalent to a 0.7 and 0.9-year increase in chronological age respectively (P < 0.001). Inverse variance MR analyses showed that reduced ' g ' is associated with genetically determined elevation of VAT, BMI and WHR (all P < 0.001). In contrast, MR did not support a causal role for blood pressure, lipid, or glycemic indices on cognition. Interpretation: We show an independent relationship between adiposity and cognition in a multi-ethnic Asian population. MR analyses suggest that both visceral adiposity and raised BMI are likely to be causally linked to cognition. Our findings have important implications for preservation of cognitive health, including further motivation for action to reverse the rising burden of obesity in the Asia-Pacific region. Funding: The Nanyang Technological University-the Lee Kong Chian School of Medicine, National Healthcare Group, National Medical Research Council, Ministry of Education, Singapore.

Global Epidemiology and Genetics of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is one of the leading cancers worldwide. Classically, HCC develops in genetically susceptible individuals who are exposed to risk factors, especially in the presence of liver cirrhosis. Significant temporal and geographic variations exist for HCC and its etiologies. Over time, the burden of HCC has shifted from the low-moderate to the high sociodemographic index regions, reflecting the transition from viral to nonviral causes. Geographically, the hepatitis viruses predominate as the causes of HCC in Asia and Africa. Although there are genetic conditions that confer increased risk for HCC, these diagnoses are rarely recognized outside North America and Europe. In this review, we will evaluate the epidemiologic trends and risk factors of HCC, and discuss the genetics of HCC, including monogenic diseases, single-nucleotide polymorphisms, gut microbiome, and somatic mutations.

Understanding cancer predisposition in Singapore: What's next.

Knowledge of an underlying genetic predisposition to cancer allows the use of personalised prognostic, preventive and therapeutic strategies for the patient and carries clinical implications for family members. Despite great progress, we identified six challenging areas in the management of patients with hereditary cancer predisposition syndromes and suggest recommendations to aid in their resolution. These include the potential for finding unexpected germline variants through somatic tumour testing, optimal risk management of patients with hereditary conditions involving moderate-penetrance genes, role of polygenic risk score in an under-represented Asian population, management of variants of uncertain significance, clinical trials in patients with germline pathogenic variants and technology in genetic counselling. Addressing these barriers will aid the next step forward in precision medicine in Singapore. All stakeholders in healthcare should be empowered with genetic knowledge to fully leverage the potential of novel genomic insights and implement them to provide better care for our patients.