Rethinking Hereditary Cancer Testing Eligibility: A Five-Domain Framework Beyond Family History Gating

Technical Summary: Rethinking Hereditary Cancer Testing Eligibility

Problem Statement
Current hereditary cancer testing guidelines, primarily the National Comprehensive Cancer Network (NCCN) criteria, rely heavily on family history gating and specific age or pathology thresholds. The authors argue that these criteria fail to identify a substantial proportion of germline pathogenic or likely pathogenic (P/LP) variant carriers. Evidence from unselected cohorts indicates that NCCN criteria identify only 70.1% of carriers in breast cancer and 58.1% in prostate cancer. Furthermore, prospective studies comparing in-criteria versus out-of-criteria patients have found no statistically significant difference in carrier prevalence, challenging the discriminative validity of current gating mechanisms.

The authors identify three critical gaps in existing frameworks:

1. Sensitivity: Family-history-dependent gating excludes many carriers, particularly those with small pedigrees or no known family history.
2. Equity: Current criteria disproportionately penalize racial and ethnic minority populations who may have limited access to family history information or smaller known pedigrees due to structural disparities.
3. Clinical Utility: Guidelines fail to integrate Polygenic Risk Scores (PRS) for risk stratification and rely on single-variant cascade testing, which misses actionable variants in other genes among relatives.

Methodology
The KinGen Criteria were developed through a targeted, iterative review of peer-reviewed literature published between 2017 and 2026. The authors utilized an inductive domain-mapping approach to translate evidence into a structured testing framework.

• Data Sources: PubMed/MEDLINE, PMC, journal websites, and hand-searched reference lists were reviewed.
• Selection Criteria: Citations were retained if they reported performance of testing criteria in defined cohorts, provided gene/ancestry-specific yield data, quantified PRS discriminatory contribution, or constituted major society guidelines.
• Framework Development: Evidence gaps were clustered into thematic domains. Each domain required support from at least two independent published studies.
• Comparative Analysis: The proposed framework was subjected to a structured, domain-by-domain comparison against NCCN v3.2026, NCCN v1.2025, and the ASBrS 2019 Consensus Guideline across six dimensions: cancer triggers, trigger mechanisms, unaffected individual eligibility, PRS integration, cascade testing approach, and provisions for underrepresented populations.
• Constraints: No patient-level data were used; the study constitutes a literature synthesis. AI tools were used for literature search guidance and manuscript drafting but were reviewed and edited by the authors.

Key Contributions: The Five-Domain KinGen Framework
The paper proposes the "KinGen Criteria," a five-domain framework designed to extend current guidelines:

• Domain A: Universal Diagnosis-Triggered Testing. Establishes germline testing for eight cancer types (breast, ovarian/fallopian tube/primary peritoneal, pancreatic, colorectal, endometrial, prostate, diffuse gastric) independent of age or family history. It also includes any cancer diagnosed at age ≤25 and patients with ≥2 synchronous or metachronous primary cancers. Notably, prostate cancer is included as a universal trigger independent of metastatic status or family history, whereas NCCN restricts testing to metastatic or high-risk disease.
• Domain B: Point-of-Care Paired Somatic/Germline Testing. Mandates that for all Domain A cancers, comprehensive germline multi-gene panel testing and somatic tumor NGS profiling be ordered simultaneously at diagnosis. This eliminates the 2–4 week sequential lag inherent in current workflows, enabling immediate germline-dependent treatment decisions (e.g., PARP inhibitor eligibility).
• Domain C: Unaffected Individual Eligibility. Replaces strict age-of-onset thresholds with a cascade model. If an affected family member meets testing criteria, their first- and second-degree unaffected relatives are eligible regardless of age. It includes a "Limited Family Structure Override" (C13) for individuals with adoption, early parental death, estrangement, or small family size, acknowledging that uninformative family history is not equivalent to a confirmed negative history.
• Domain D: Polygenic Risk Score (PRS) Integration. Formally incorporates PRS into breast cancer risk stratification.
  • D1: PRS evaluation for gene-negative patients with family history.
  • D2: Refinement of penetrance estimates for moderate-penetrance variant carriers (e.g., ATM, CHEK2).
  • D3: Final risk stratification via validated integrated models (BOADICEA v6/CanRisk or Tyrer-Cuzick v8) combining PRS, pedigree, reproductive history, and mammographic density.
  • D4: Offering PRS + germline testing to unaffected women undergoing risk assessment, regardless of insurance eligibility for germline testing.
• Domain E: Multi-gene Panel Cascade Testing. Mandates that cascade testing for relatives of P/LP variant carriers utilize a comprehensive hereditary multi-gene pan-cancer panel rather than single-variant (site-specific) testing. This addresses the finding that 4.9–6.2% of relatives carry actionable variants in genes different from the known familial variant.

Results and Comparative Analysis
The comparative analysis (Table 1) demonstrates that the KinGen Criteria extend existing frameworks in every dimension. While they match NCCN breadth regarding most cancer types, they expand coverage by adding prostate cancer as a universal trigger independent of metastatic status, whereas NCCN limits prostate testing to metastatic or high-risk cases.

• Sensitivity: By removing family history gating for diagnosis-triggered testing, the framework aims to capture the ~30% of carriers missed by current NCCN criteria in breast cancer and ~42% in prostate cancer.
• Equity: The framework explicitly addresses structural inequities by codifying exceptions for limited family structures and removing age thresholds that rely on often misreported data.
• Clinical Workflow: The paired somatic/germline approach (Domain B) is presented as a standard of care to prevent treatment delays, contrasting with the sequential NCCN workflow.
• Risk Stratification: Domain D operationalizes PRS integration, which current NCCN guidelines explicitly exclude from clinical management, arguing that PRS-integrated models (e.g., BOADICEA v6) achieve clinically meaningful reclassification and calibration at decision thresholds.

Significance and Claims
The authors claim the KinGen Criteria provide an evidence-based, clinically actionable framework that outperforms existing guidelines in sensitivity, equity, and comprehensiveness.

• Evidence Base: The framework is grounded in primary evidence showing that family-history gating excludes a substantial fraction of carriers and that PRS-integrated models improve risk stratification accuracy beyond traditional models.
• Structural Change: The paper argues that the shift from "family-history gating" to "diagnosis-triggered" and "cascade-based" testing is necessary to close documented racial/ethnic disparities and improve clinical yield.
• Future Validation: The authors explicitly state that the KinGen Criteria have not yet been prospectively validated. They call for ongoing prospective validation in diverse cohorts, cost-effectiveness modeling, and engagement with NCCN committees for potential incorporation. The paper positions itself as a proposal for a new standard of care based on current literature, rather than a report of completed clinical trials.