Germline CDH1 (E-cadherin) pathogenic variant in invasive lobular breast carcinoma — INFO...

Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.

ID	`RF-BREAST-CDH1-LOBULAR-CANDIDATE`
Type	Red flag
Status	reviewed 2026-04-29 \| pending_clinical_signoff
Diseases	`DIS-BREAST` `DIS-GASTRIC`
Sources	`SRC-NCCN-BREAST-2025` `SRC-NCCN-GASTRIC-2025`

Red Flag Origin

Definition	Germline CDH1 (E-cadherin) pathogenic variant in invasive lobular breast carcinoma — INFORMATIONAL signal. CDH1 is the hereditary diffuse gastric cancer (HDGC) gene; carriers face ~40-50% lifetime invasive lobular breast cancer risk and ~70% diffuse gastric cancer risk. No PARPi indication and no breast-cancer-specific systemic therapy decision keyed on CDH1 status. Surfaces in MDT brief to trigger: (1) cascade testing of first-degree relatives, (2) prophylactic total gastrectomy discussion (HDGC management standard per NCCN hereditary GI), (3) enhanced breast surveillance vs risk-reducing mastectomy counseling. Lobular subtype itself influences endocrine-therapy selection (CDK4/6i + AI typical; some chemotherapy regimens less effective in lobular vs ductal), but that is subtype-driven, not CDH1-genotype-driven.
Clinical direction	investigate
Category	high-risk-biology

Trigger Logic

{
  "any_of": [
    {
      "finding": "cdh1_germline",
      "value": "pathogenic"
    },
    {
      "finding": "cdh1_status",
      "value": "pathogenic"
    },
    {
      "finding": "germline_cdh1",
      "value": "pathogenic"
    },
    {
      "finding": "cdh1_pathogenic",
      "value": true
    }
  ],
  "type": "biomarker"
}

Notes

References BIO-CDH1-GERMLINE. Genetic counseling mandatory; total prophylactic gastrectomy is the established HDGC standard (endoscopic surveillance is INADEQUATE for diffuse-type detection). No NCCN hereditary-cancer panel source exists in KB — disease-specific NCCN sources used; flagged in commit body. Family-history red-flag pattern: lobular breast + diffuse gastric in same kindred is the canonical CDH1 presentation. RF distinct from any future breast RF that would key on lobular HISTOLOGY (subtype != genotype).

Used By

No reverse references found in the YAML corpus.