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Multiple primary cancers

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Cancer Presentations/Family-history-driven

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A patient with two or more separate primary cancers (not metastases from a single tumor), or a strikingly cancer-rich family history. Both situations elevate prior probability of a hereditary cancer syndrome from baseline (~10% of all cancers) into the range where multi-gene panel testing is justified, often pre-test counseling-required by insurers.

The combination of cancers narrows the syndrome before the panel is sent. Pattern recognition compresses what would otherwise be a 100-gene fishing expedition into a targeted question.

  • Breast plus ovarian in the same patient or pedigree: hereditary breast and ovarian cancer (BRCA1, BRCA2). BRCA1 skews to earlier breast and serous ovarian; BRCA2 adds male breast, pancreatic, prostate.
  • Breast plus thyroid plus endometrial with macrocephaly and mucocutaneous findings: PTEN hamartoma tumor syndrome (Cowden).
  • Breast plus diffuse gastric (especially signet-ring): CDH1 (hereditary diffuse gastric cancer, lobular breast). Prophylactic gastrectomy is on the table.
  • Sarcoma plus breast plus brain plus adrenocortical, any age: Li-Fraumeni syndrome (TP53). The "Chompret" criteria are looser than classic LFS and capture more carriers.
  • Colon plus endometrial plus ovarian plus gastric plus urinary tract: Lynch syndrome (MMR genes; EPCAM for some MSH2 silencing).
  • Colon polyposis plus colon cancer (young): familial adenomatous polyposis (APC), MAP (MUTYH, biallelic), or attenuated Lynch.
  • Renal cell carcinoma plus skin leiomyomas (or uterine fibroids): hereditary leiomyomatosis and renal cell cancer (FH). The RCC is aggressive type 2 papillary.
  • Renal cell plus cerebellar hemangioblastoma plus pheochromocytoma plus retinal angioma: von Hippel-Lindau syndrome (VHL).
  • Pancreatic plus melanoma: CDKN2A (familial atypical multiple mole melanoma, FAMMM).
  • Medullary thyroid plus pheochromocytoma plus hyperparathyroidism: multiple endocrine neoplasia type 2 (RET). 2B has mucosal neuromas, marfanoid habitus, intestinal ganglioneuromatosis.
  • Paraganglioma plus GIST (and pulmonary chondroma): Carney triad (sporadic, young women) versus Carney-Stratakis dyad (germline SDHx).
  • Two primary cancers in one organ (e.g. metachronous bilateral breast) is itself a syndrome signal, even without a family history.
  • Synchronous endometrial and ovarian (in a young woman) is classically Lynch.
  • A clean-looking family with three of the LFS cancers in close relatives still counts.
  • The cancer count in a family matters less than the types and ages.
  • Three-generation pedigree with cancer type, age at diagnosis, and bilaterality. Update it at every visit; relatives develop cancers between appointments.
  • Pathology re-review with attention to molecular markers (MSI/IHC for Lynch, IHC for SMARCB1 loss in rhabdoid tumors, FH IHC in HLRCC-suspect RCC).
  • Multi-gene cancer panel scoped to the phenotype. Most centers default to BRCA-focused panels for breast/ovary patterns and a broader 50 to 100 gene panel for ambiguous family histories.
  • Take the pedigree before sending the panel; it changes which panel you order.
  • Bilateral breast cancer under 50 even with a "negative" family history still warrants testing.
  • A clean panel does not rule out a hereditary syndrome. Variants in non-coding regions, deep intronic splice variants, and undiscovered genes still happen.