Predictive Testing for Tumor Predisposition Syndromes in Pediatric Relatives: An Asian Experience

Multi-locus inherited neoplasia alleles syndromes in cancer: implications for clinical practice

The popularity of multi-gene testing has identified more families with two or more pathogenic variants (PV) in cancer predisposition genes, also known as 'MINAS' (multilocus inherited neoplasia alleles syndromes). They are at risk of suboptimal treatment and management as little on this topic is known. We conducted a systematic review of published MINAS cases within cancer predisposition genes to understand their association with more severe presentations. We analysed 413 MINAS carriers, which included 33 novel cases from the Cancer Genetics Service, National Cancer Centre Singapore. Statistical tests were conducted to assess association between carrier characteristics and the number PV identified. Results suggest that MINAS carriers have more malignancies (31.7% vs 21.5% vs 10.3% %; p < 0.001), a younger median age of first cancer diagnosis (40.0 vs. 44.0 vs. 49.0 years; p < 0.001) and an early onset of cancer (defined as <5% PV-associated cancer risk at age of diagnosis) (24.9% vs 7.7% vs 4.7%; p < 0.001) compared to monoallelic and non-carriers. We also studied the association of clinical characteristics by the dominant or recessive nature of PV harboured, where more dominant-dominant (D-D) carriers reported multiple malignancies (34.0%), compared to dominant-recessive (D-R) (23.9%) and recessive-recessive (R-R) carriers (20%;) (p = 0.051). Our findings suggest that MINAS carriers are prone to more and younger malignancies and the dominant or recessive nature of PV within double carriers can affect clinical presentation. We suggest a framework to guide management based on the dominant or recessive nature of PV within double PV carriers.

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.

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.