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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Hereditary cancer syndromes and genetic referral

Oncology and palliative care · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull

Overview

Recognise patterns of inherited cancer predisposition, take and verify a three-generation pedigree, refer through genomic services, and manage testing, surveillance and family communication without acting on uncertain variants.

Inherited cancer syndromes arise from constitutional variants that reduce tumour suppression, DNA repair or other protective functions across many cells. Examples include hereditary breast and ovarian cancer, Lynch syndrome, familial adenomatous polyposis, Li-Fraumeni syndrome and endocrine tumour syndromes. Penetrance varies by gene, variant, organ, age, sex and environment; carrying a variant increases probability but does not guarantee cancer.

Recognition begins with phenotype rather than a consumer test. Record all primary cancers, age, bilateral or multifocal disease, premalignant burden and the maternal and paternal line separately. Tumour features such as mismatch-repair deficiency can trigger germline assessment, but somatic causes remain possible. The NHS Genomic Medicine Service and National Genomic Test Directory define eligibility and appropriate panels.

Testing should lead to an actionable plan. A confirmed familial variant permits targeted predictive testing, while a negative familial test can reduce certain inherited risks. An uninformative panel does not erase a strong pedigree. Surveillance, risk-reducing surgery and chemoprevention are syndrome-specific and require absolute-risk discussion, fertility and menopause implications, and psychological support.

Key points

  • Most cancers are not caused by a single inherited high-penetrance variant, but age, tumour pattern and family history can identify people who need genomic assessment.
  • Referral clues include unusually young cancer, multiple primaries, bilateral disease, characteristic rare tumours and several related cancers on one side of a family.
  • Take a three-generation pedigree with cancer site, age at diagnosis, ancestry where relevant and results of any previous testing; verify pathology when major decisions depend on it.
  • Test an affected relative first when possible because a negative result in an unaffected person may be uninformative.
  • A pathogenic or likely pathogenic germline variant can guide surveillance, risk-reducing options, targeted treatment and predictive testing of adult relatives.
  • A variant of uncertain significance is not a diagnosis and must not drive prophylactic surgery or predictive family testing.
  • Consent covers possible results, limitations, family implications, data use, reproductive choices and the possibility of unexpected information.
  • People without an identified variant may still warrant enhanced surveillance when their verified family history remains strongly suggestive.

Aetiology

01

Pathogenic germline variant

A constitutional variant impairs a tumour-suppressor, DNA-repair or other protective pathway across tissues, increasing the lifetime probability of characteristic cancers.

02

De novo or inherited origin

The variant may pass through a family or arise de novo in the affected person, so absence of family history does not exclude susceptibility.

03

Polygenic and unexplained familial risk

Some clustered families reflect many lower-impact variants, shared exposures or undiscovered genes rather than one currently identifiable high-penetrance cause.

Pathophysiology

  1. 1
    Constitutional vulnerability exists

    Every susceptible cell carries one impaired pathway component, reducing the additional somatic events needed for a malignant clone to emerge.

  2. 2
    Second hits accumulate

    Loss or inactivation of the remaining functional allele can remove tumour suppression or DNA repair in an individual cell lineage.

  3. 3
    Tissue-specific penetrance develops

    Hormonal environment, organ biology, age and other genes determine where and when cancers arise despite the variant being present throughout the body.

  4. 4
    Genomic instability accelerates

    Repair syndromes increase mutation accumulation, creating multiple primary cancers and characteristic tumour signatures that can also influence treatment response.

Clinical features and red flags

Young-onset cancer

Diagnosis substantially earlier than the usual population pattern raises inherited susceptibility, especially with rare histology or another primary.

Multiple related primaries

Bilateral breast cancer, colorectal and endometrial cancer, multiple endocrine tumours or repeated polyps can form a recognisable syndrome pattern.

Vertical family pattern

Related cancers across successive generations on the same lineage may fit dominant inheritance, while small families and sex distribution can conceal it.

Tumour biomarker clue

Mismatch-repair loss, characteristic mutational signature or another validated tumour feature can justify germline testing but is not itself constitutional proof.

Known familial variant

A documented pathogenic variant in a blood relative permits targeted predictive testing with a clearer interpretation than broad screening.

Investigations

  1. 01
    Three-generation pedigreeFirst step
    Why
    Estimate whether personal and family pattern meets genomic referral criteria.
    Interpretation and limitations
    Record exact cancer type, age, lineage, multiple primaries and unaffected relatives; verify pathology or certificates when feasible and consequential.
  2. 02
    Tumour biomarker testing
    Why
    Identify a phenotype associated with inherited susceptibility and guide treatment.
    Interpretation and limitations
    Interpret protein loss or sequencing with pathology and somatic explanations; abnormal tumour findings often require constitutional confirmation.
  3. 03
    Germline multigene or targeted test
    Why
    Identify a pathogenic constitutional variant under the national test directory.
    Interpretation and limitations
    Choose affected-first and syndrome-directed testing where possible; explain uncertain, incidental and technically undetected variants before sampling.
  4. 04
    Predictive familial-variant test
    Why
    Determine whether an adult relative carries a known pathogenic family variant.
    Interpretation and limitations
    Pre-test counselling clarifies possible positive and true-negative results, surveillance consequences and confidentiality; testing minors depends on childhood actionability.
  5. 05

Differential diagnosis

01

Sporadic early cancer

Cancer can occur young without a high-penetrance germline variant, particularly when tumour and pedigree features do not form a recognised syndrome.

02

Shared environmental exposure

Smoking, infection, occupation or another familial exposure can cluster cancer without Mendelian inheritance and requires its own prevention strategy.

03

Polygenic familial aggregation

Multiple common variants can raise risk across a family without producing a single-gene pattern or an informative standard panel result.

04

Incorrect family history

Benign tumours, metastases recorded as new primaries and uncertain ages can falsely create a syndrome pattern until diagnoses are verified.

Management

01RecogniseBuild and verify inherited-risk evidenceFirst stepPersonal or family cancer features suggest more than sporadic risk.+
  1. 1Take a three-generation pedigree and obtain the existing pathology or family genetic report rather than relying on a remembered gene name.
  2. 2Check the current National Genomic Test Directory or specialist criteria and refer with the features that meet them.
  3. 3Address immediate cancer treatment separately; urgent therapeutic biomarker testing may run in parallel with fuller genetics assessment.
02TestUse the most informative personGenomic assessment confirms that germline testing is appropriate.+
  1. 1Where possible, test an affected relative whose tumour and age best represent the suspected syndrome, after informed consent.
  2. 2Use a targeted familial test when a pathogenic variant is already documented; use an indicated panel when the causal gene is unknown.

Complications

01

Multiple primary cancers

Persisting constitutional risk can produce new independent cancers after successful treatment of the first, requiring lifelong syndrome-specific surveillance.

02

Cancer in relatives

A pathogenic familial variant may place blood relatives at substantial preventable risk if cascade testing and surveillance are not offered.

03

Preventive-treatment harm

Risk-reducing surgery or chemoprevention can cause infertility, early menopause, bleeding or other morbidity when benefits and timing are not individualised.

04

Psychological and family burden

Uncertainty, survivor guilt, communication difficulties and differing preferences about testing can strain wellbeing and relationships across generations.

Monitoring and follow-up

  • Maintain a verified pedigree and update new family cancers, deaths and genetic results because eligibility and interpretation can change.
  • Track completion of syndrome-specific surveillance rather than merely recording that advice was given.
  • Review variant classification through the responsible genetics service; do not reinterpret a laboratory result from ungoverned internet databases.
  • Monitor physical and psychological consequences of surveillance, risk-reducing surgery, early menopause and reproductive decisions.
  • Ensure cancer teams know treatment-relevant inherited findings while sharing only the family information needed for care.

Special situations

Paternal history counts

Dominant cancer variants pass through any sex, so breast or ovarian patterns on the father's side remain clinically relevant.

Affected-first is powerful

A negative panel in an unaffected relative cannot exclude a family syndrome when no affected person's causal variant is known.

Tumour and germline differ

Mismatch-repair loss or a pathogenic tumour variant can arise somatically and needs the appropriate constitutional confirmation pathway.

VUS is not actionable

Uncertain variants are expected during broad testing and should not change surgery, surveillance or relatives' care outside evidence review.

Negative can remain high risk

Testing technology and gene knowledge are incomplete; a compelling verified pedigree may still justify clinical surveillance.

Common pitfalls

  1. 01

    Ignoring the paternal lineage in clinical practice.

  2. 02

    Recording cancer without age or primary site.

  3. 03

    Testing an unaffected relative first without reason.

  4. 04

    Treating a tumour variant as germline proof.

  5. 05

    Operating because of a variant of uncertain significance.

  6. 06

    Assuming a negative panel removes pedigree risk.

  7. 07

    Sharing relatives' information beyond necessary care.

Practice

Two practice questions

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Question 1 of 2
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Oncology and palliative careOriginal SBA

Variant of uncertain significance

A healthy woman with a strong family history receives a hereditary cancer panel showing only a variant of uncertain significance. What is the appropriate action?

Choose one answer, then submit
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Sources and review status6 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • Genomics Education: family history of cancerPedigree assessment, red flags and referral considerations for possible inherited cancer predisposition.
  • NHS England National Genomic Test DirectoriesCurrent national eligibility and test scope for validated constitutional cancer investigations.
  • Royal College of Pathologists cancer datasetsTumour biomarkers and pathological features that can trigger inherited-risk assessment.
  • NICE shared decision making recommendationsConsent, uncertainty and preference-sensitive preventive decisions.
  • Genomics Education: variant of uncertain significanceWhy a VUS is not actionable and must not direct predictive testing or irreversible prevention.
  • Genomics Education: predictive testingTesting unaffected relatives for a known familial pathogenic variant through a consented genetics pathway.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem ·

Syndrome-specific baseline assessment
Why
Detect existing disease and plan future surveillance after diagnosis.
Interpretation and limitations
Organ tests and intervals follow current specialist protocols; broad whole-body testing is not automatically appropriate for every syndrome.
  • 3Return pathogenic, negative and uncertain results with their distinct meanings and confirm who owns reclassification and family communication.
    • 03ActTranslate a confirmed risk into careA pathogenic variant or strongly suggestive uninformative pedigree remains after testing.+
    1. 1Create an organ-specific surveillance plan and discuss risk-reducing surgery or medicine only where evidence supports the individual's absolute risk.
    2. 2Offer cascade testing through approved family-contact processes while preserving the patient's confidentiality and relatives' right not to know.
    3. 3Include reproductive options, treatment implications, menopause or fertility effects and psychological support, reviewing the plan as guidance evolves.
    Content changes
    Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom