# Automatic germline testing for every cancer type where it changes care

Source: https://onco.cc/ideas/idea-prev-reflex-germline-testing/  
OnCo record `idea-prev-reflex-germline-testing` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Anyone with ovarian, pancreatic, metastatic prostate or mismatch-repair-deficient colorectal cancer should be tested for inherited mutations, yet testing rates fall well short. Making it an automatic, opt-out laboratory step triggered by pathology, as reflex mismatch-repair testing already is, would close the gap.

## Summary

Anyone with ovarian, pancreatic, metastatic prostate or mismatch-repair-deficient colorectal cancer should have germline testing, but testing rates fall well short, so this idea makes it an automatic opt-out laboratory step triggered by pathology, as reflex MMR and MSI testing already is, mainstreamed by oncologists with genetics support only for positives. Reflex mismatch-repair testing succeeded and mainstreaming trials show oncologists can consent patients. The aim is near-universal testing in eligible groups and proportionally more cascade testing of relatives. The test is health-system implementation with monthly testing-rate dashboards. Being tested at scale, it addresses the bottleneck Inherited risk is mostly unidentified.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Reflex opt-out testing raises germline testing to at least 90% in eligible groups and increases cascade testing of relatives proportionally.
- Rationale: Reflex mismatch-repair testing succeeded, and mainstreaming trials show oncologists can consent patients.
- Proposed test: Health-system implementation with monthly testing-rate dashboards.
- Maturity: being-tested-at-scale
- Actor: clinic

## Sources

- Bottleneck evidence (Inherited risk is mostly unidentified): Childers et al., National estimates of genetic testing in women with breast or ovarian cancer (JCO 2017): https://doi.org/10.1200/JCO.2017.73.6314

## Connected records

- roadmaps: [Cancer prevention roadmap: tobacco control and vaccines → biomarker-guided chemoprevention → interception in carriers](https://onco.cc/roadmaps/prevention-roadmap/), [Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch](https://onco.cc/roadmaps/prostate-roadmap/)
- ideas: [Test every man for DNA repair faults on the day his prostate cancer is found to have spread, not three treatments later](https://onco.cc/ideas/idea-prostate-hrr-testing-at-metastatic-diagnosis/)
- cancers: [BRCA or PALB2-mutant pancreatic ductal adenocarcinoma](https://onco.cc/cancers/brca-palb2-pdac/), [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Early-onset colorectal cancer (under 50)](https://onco.cc/cancers/early-onset-colorectal/), [KRAS wild-type pancreatic ductal adenocarcinoma](https://onco.cc/cancers/kras-wild-type-pdac/), [Mismatch repair deficient (MSI-high) pancreatic ductal adenocarcinoma](https://onco.cc/cancers/msi-high-pdac/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- fronts: [Diagnostics & Biomarkers](https://onco.cc/fronts/diagnostics/), [Prevention & Risk](https://onco.cc/fronts/prevention/)
- technologies: [Germline (hereditary) testing](https://onco.cc/technologies/germline-testing/)
- terms: [Germline vs somatic mutations](https://onco.cc/terms/germline-vs-somatic/), [Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)](https://onco.cc/terms/msi/)
- bottlenecks: [Inherited risk is mostly unidentified](https://onco.cc/bottlenecks/b-hereditary-risk/)
- key papers: [Inherited DNA-repair gene mutations in men with metastatic prostate cancer](https://onco.cc/key-papers/paper-pritchard-inherited-dna-repair-metastatic-prostate-nejm-2016/), [National Estimates of Genetic Testing in Women With a History of Breast or Ovarian Cancer](https://onco.cc/key-papers/paper-childers-j-clin-oncol/)

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