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Platform 1 — Hereditary Cancer and Adult Genetics

ACMG 2026's primary cancer-genetics platform session — clinical-lab cohort readouts and classification updates anchored on BRCA1/2, PALB2, and Lynch-syndrome gene-set (MLH1, MSH2, MSH6, PMS2, EPCAM), plus the universal-testing implementation question.

  • Speaker / institution: Multiple platform speakers (clinical-lab medical directors + academic hereditary-cancer program PIs from major US programs — MGB, MSK, MD Anderson, Mayo, Stanford, Penn, Dana-Farber, City of Hope, plus commercial labs Ambry / GeneDx / Color); specific slate TBC from GIM supplement
  • Anchor type: cohort + clinical
  • Day / session: Day 3–4 (Mar 12–13, 2026) — Platform 1, Hereditary Cancer and Adult Genetics session
  • Status: post-meeting; verified Platform 1 designation per ACMG program; per-abstract speakers and cohort numerics TBD pending GIM supplement and Digital Edition recordings

Headline finding

Platform 1 is the load-bearing cancer-genetics slot of the 2026 program — six to eight platform talks covering (1) BRCA1/2 and PALB2 panel-classification updates, including VUS-reclassification cohort outcomes and the impact of ClinGen Hereditary Breast/Ovarian/Pancreatic VCEP curations; (2) Lynch syndrome (MLH1, MSH2, MSH6, PMS2, EPCAM) — current MMR-gene classification landscape, universal-tumor-screening implementation data, and downstream cascade-testing yield; (3) the broader universal-testing-vs-criteria-based-testing debate for breast / ovarian / colorectal / pancreatic cancer. Specific per-talk cohort sizes, reclassification rates, and detection-yield percentages TBD pending supplement.

Methodology / framework

Clinical-lab cohort designs: multi-site hereditary-cancer panel submissions analyzed retrospectively for (a) pathogenic / likely-pathogenic detection rate stratified by ordering indication, (b) VUS reclassification rate using ClinGen VCEP-specific evidence frameworks (PS3 functional evidence recalibration, splice-evidence PVS1, multifactorial likelihood ratios for BRCA), (c) cascade-testing uptake from probands to first-degree relatives, (d) outcome implications for risk-reducing surgery and surveillance. ACMG/AMP 2015 framework with ClinGen Hereditary Cancer VCEP gene-specific specifications.

Lab-translation deep dive

Validation requirements. Hereditary-cancer-panel labs are in a constant re-validation cycle as ClinGen VCEPs publish gene-specific evidence-code recalibrations. Each VCEP update (BRCA PS3 functional-evidence weighting, MMR-gene PVS1 splice-evidence, multifactorial-likelihood evidence integration for BRCA1/2) triggers a re-classification sweep across the historical VUS population and a validation refresh of the curation pipeline. CNV detection (BRCA1/2 exon-level, MLH1 / MSH2 / EPCAM 5' deletion, MSH2 inversion) remains a lab-stack differentiator and a recurring validation concern.

Lab-stack changes. Universal-testing scale (universal breast / ovarian / pancreatic / colorectal hereditary-cancer testing pilots) collapses sample volumes onto fewer reference labs and demands faster TAT (≤14 days as a working floor for treatment-decision pathways like PARP-inhibitor eligibility). Pipeline-side: structural-variant calling parity with SNV calling, exon-CNV detection, splice-impact prediction integration (SpliceAI as a near-universal PP3 / BP4 input), and ClinGen-VCEP-aware classification logic.

Regulatory / insurance. FDA LDT final rule applies — most hereditary-cancer panels operate as LDTs, with FDA-cleared kits (Myriad BRCA, Ambry / GeneDx panels) coexisting. Payer coverage hinges on NCCN guidelines (which moved toward universal breast / colorectal testing in recent revisions); cascade-testing reimbursement for first-degree relatives is the load-bearing implementation question for the universal-testing axis.

Variant curation. ClinGen VCEPs (HBOP — BRCA1/2; HBOP — PALB2; InSiGHT for MMR genes; CDH1; PTEN; etc.) provide the gene-specific evidence frameworks. VUS reclassification cadence (Open Question #3) reflects steady-state VCEP throughput. Multifactorial-likelihood evidence integration for BRCA1/2 is the most-mature curation paradigm — other genes are catching up.

Where it fits in the corpus

  • AACR 2026: Hereditary Cancer / Pediatric Cancer Predisposition / germline-somatic integration sessions (Apr 17–22, Chicago) — 4–6 week follow-on with the same PI pool
  • ASCO 2026: PARP inhibitor and Lynch-targeted ICI trial-eligibility (BRCA → olaparib / niraparib / talazoparib / rucaparib; MMRd → pembrolizumab / dostarlimab)
  • SABCS 2026: hereditary-breast-cancer panel readouts
  • ASHG 2026: statistical-genetics cancer-PRS and panel-design methods sibling talks
  • Related ACMG 2026: acmg-sf-v33-secondary-findings.md, chip-mosaicism-cancer-panels.md, llm-acmg-amp-reproducibility.md

Open questions

  • Universal vs criteria-based testing for breast/ovarian/colorectal — does the data finally support universal at the population level?
  • PALB2 risk-reducing-surgery thresholds — when does PALB2 reach BRCA-equivalent management?
  • VUS reclassification cadence — what's the steady-state rate now that ClinGen VCEPs are mature?

Sources