EPCAM Deletion Test: Lynch Syndrome, Colon Cancer Risk, and Results

An EPCAM deletion test looks for specific inherited losses of DNA at the end of the EPCAM gene that can cause Lynch syndrome. EPCAM is not itself a DNA mismatch repair gene. Instead, certain deletions involving its 3′ end can trigger abnormal methylation and shutdown of the neighboring MSH2 gene in EPCAM-expressing tissues. Loss of MSH2 function then raises the risk of colorectal cancer and, depending on the deletion, other Lynch syndrome cancers. This mechanism is why routine EPCAM sequencing alone is not enough: the laboratory must use a method that can detect exon-level or larger deletions. Testing is usually performed on blood or saliva as part of a Lynch syndrome panel that includes MLH1, MSH2, MSH6, PMS2, and EPCAM deletion analysis. A positive result has implications for lifelong cancer surveillance and for relatives, because the deletion is generally inherited in an autosomal dominant pattern. A negative result does not rule out Lynch syndrome if tumor testing, family history, or another mismatch repair gene remains suspicious.

• Only certain deletions involving the 3′ end of EPCAM are established causes of Lynch syndrome.
• EPCAM deletions cause disease by silencing the adjacent MSH2 gene, not by removing a mismatch repair protein directly.
• Tumors often show loss of MSH2 and MSH6 proteins on immunohistochemistry and may be microsatellite instability-high.
• A pathogenic EPCAM deletion usually gives each child and full sibling a 50% chance of carrying the familial deletion.
• Sequence-only testing can miss the diagnosis; deletion and duplication analysis is required.

Table of Contents

• How EPCAM Deletions Cause Lynch Syndrome
• When EPCAM Testing Is Recommended
• Test Methods and Specimens
• Understanding Positive and Negative Results
• Cancer Risks and Surveillance
• Family Testing and Reproductive Options
• Limitations and Next Steps

How EPCAM Deletions Cause Lynch Syndrome

Lynch syndrome usually results from a germline pathogenic variant in MLH1, MSH2, MSH6, or PMS2. These genes produce proteins that repair DNA-copying errors. EPCAM is different. It sits immediately upstream of MSH2 on chromosome 2, and specific deletions that remove the terminal part of EPCAM can disrupt the normal stop signal for EPCAM transcription.

When transcription continues past the deleted EPCAM region, it can extend into the neighboring MSH2 promoter. In cells where EPCAM is active, this abnormal read-through promotes methylation of the MSH2 promoter. Methylation acts like an off switch, reducing or eliminating MSH2 expression. Because MSH2 normally pairs with MSH6, tumors that lose MSH2 often also lose MSH6 protein on immunohistochemistry.

This mechanism creates several important testing rules:

• Not every EPCAM variant causes Lynch syndrome.
• Missense variants and many ordinary sequence changes in EPCAM are not established Lynch syndrome causes.
• Causative deletions usually involve one or more exons at the 3′ end of EPCAM.
• Some deletions extend beyond EPCAM into MSH2, producing a combined structural rearrangement.
• The extent of deletion and tissue-specific methylation can influence the cancer pattern.

A pathogenic EPCAM deletion is inherited, so it is present in constitutional DNA and can be passed through a family. It should not be confused with a somatic EPCAM change found only in a tumor. The most direct comparison is with a broader Lynch syndrome genetic test, which evaluates all major genes and structural mechanisms rather than EPCAM alone.

The tumor consequence is mismatch repair deficiency. DNA errors accumulate, especially in repetitive regions called microsatellites. This can produce microsatellite instability-high, or MSI-high, status. Mismatch repair deficiency has diagnostic importance for Lynch syndrome screening and may also influence cancer treatment, including immunotherapy decisions in some tumor types.

EPCAM deletions account for a small minority of Lynch syndrome families. They are uncommon enough that an isolated EPCAM test is usually ordered only when a familial deletion is known or when tumor and family findings specifically point toward the EPCAM-MSH2 region. For most people starting an evaluation, a multigene Lynch syndrome panel is more efficient.

When EPCAM Testing Is Recommended

The clearest reason to test is a known pathogenic EPCAM deletion in a blood relative. In that situation, targeted familial-variant testing can determine whether the person inherited the same deletion. A targeted test is usually less expensive and easier to interpret than repeating a broad panel, provided the laboratory receives the exact family report.

EPCAM deletion analysis is also appropriate when a person has colorectal, endometrial, or another Lynch-associated cancer and tumor screening suggests loss of MSH2 function. A common pattern is absent MSH2 and MSH6 staining on immunohistochemistry. That pattern usually directs germline testing toward MSH2 and EPCAM, while still allowing for double somatic tumor mutations or other explanations.

Other reasons include:

• Colorectal cancer at a young age
• Multiple Lynch-associated cancers in one person
• Several relatives with colorectal or endometrial cancer across generations
• A family history previously labeled hereditary nonpolyposis colorectal cancer
• An MSI-high tumor without an adequate sporadic explanation
• Prior negative MSH2 sequencing when deletion analysis was incomplete
• A structural rearrangement near the EPCAM-MSH2 region found by another assay

Universal mismatch repair screening of colorectal and endometrial cancers has expanded identification beyond older family-history criteria. Tumor testing is a screen, not a germline diagnosis. An abnormal tumor can result from inherited Lynch syndrome or from changes confined to the cancer. Germline testing clarifies whether the result affects the person’s lifelong risk and relatives.

A normal tumor immunohistochemistry result reduces but does not eliminate the chance of Lynch syndrome. Some pathogenic variants retain protein staining, some tumors are technically difficult, and a cancer may arise sporadically in a person who carries a predisposition. Clinical genetics review remains appropriate when the personal or family history is strongly suggestive.

People without cancer may qualify for testing based on family history. Whenever possible, testing should begin with a relative who has had a Lynch-associated cancer because that person is more likely to reveal the familial cause. If no affected relative is available, an unaffected person can still be tested, but a negative result may be less informative unless the family’s pathogenic variant is already known.

The distinction between screening and diagnostic testing is important. A hereditary cancer genetic screening test may survey multiple syndromes, while targeted EPCAM testing answers a narrower question about a specific deletion mechanism.

Test Methods and Specimens

Blood is the most common specimen for germline EPCAM testing. Saliva may also be accepted, though a new sample can be needed if DNA quality is poor. The laboratory extracts constitutional DNA and uses a method designed to identify copy-number loss across EPCAM exons and the neighboring region.

Common methods include:

• Multiplex ligation-dependent probe amplification: MLPA compares copy number across multiple exons and is widely used for deletion and duplication analysis.
• NGS-based copy-number analysis: A validated panel can infer exon-level deletions from sequencing depth, often with confirmation by another method.
• Chromosomal microarray: Useful for larger deletions, though resolution and probe placement must cover the relevant region.
• Quantitative PCR or digital PCR: Can confirm a known familial deletion or a specific exon loss.
• Long-range PCR and breakpoint analysis: May define exact deletion boundaries, especially for family studies or complex rearrangements.

Sequence analysis and deletion analysis answer different questions. Standard sequencing reads the letters within EPCAM and the mismatch repair genes. It may detect small substitutions or insertions, but it can miss deletion of one exon, several exons, or the entire gene. A complete Lynch panel should state that deletion and duplication analysis was performed for EPCAM and MSH2.

The report may describe the deletion by exons, genomic coordinates, or both. For example, it may say that EPCAM exons 8 and 9 are deleted or that a deletion extends from EPCAM into MSH2. Exact boundaries are clinically useful because not all structural changes have the same established effect. A report should classify the deletion as pathogenic, likely pathogenic, uncertain, likely benign, or benign according to available evidence.

Tumor testing uses different specimens and methods. Immunohistochemistry evaluates MLH1, PMS2, MSH2, and MSH6 protein staining. MSI testing measures instability in repetitive DNA. Tumor NGS may infer MSI and identify somatic MSH2 variants, but it does not always detect a germline EPCAM deletion reliably. A tumor result should not be treated as a substitute for validated constitutional deletion analysis.

Methylation testing can demonstrate abnormal MSH2 promoter methylation in tissues, but it is not usually the first-line germline test. EPCAM-associated methylation may be mosaic across tissues because it depends on EPCAM expression. A negative methylation result in one sample therefore needs cautious interpretation.

No fasting is required. Before collection, the patient should obtain copies of any relative’s genetic report and their own tumor pathology, immunohistochemistry, MSI, and prior genetic results. Knowing the exact familial deletion prevents a laboratory from ordering an unnecessarily broad or mismatched assay.

Understanding Positive and Negative Results

A positive result means the laboratory found a deletion that it classifies as pathogenic or likely pathogenic for EPCAM-associated Lynch syndrome. The result should specify whether the deletion is confined to the terminal EPCAM region or extends into MSH2. It establishes a hereditary cancer predisposition in the tested person and allows precise testing of relatives.

Result	Meaning	Usual response
Pathogenic or likely pathogenic terminal EPCAM deletion	Supports EPCAM-associated Lynch syndrome through MSH2 silencing	Begin gene-appropriate surveillance and offer targeted family testing
Deletion extending into MSH2	Structural variant may directly disrupt MSH2 as well as EPCAM	Manage with Lynch syndrome specialists and use exact boundaries for relatives
No familial deletion detected	True negative when the laboratory tested the known family variant	Familial EPCAM risk is not inherited; screening follows remaining personal and family factors
No deletion detected on an initial evaluation	Does not exclude variants in MLH1, MSH2, MSH6, PMS2, or other genes	Review whether a complete Lynch or hereditary cancer panel is needed
Variant or rearrangement of uncertain significance	Evidence is insufficient to establish Lynch syndrome	Do not use alone for predictive family testing or irreversible risk-reducing decisions

A true negative is most powerful when a pathogenic family deletion is known. If a parent carries a defined EPCAM deletion and the tested adult child does not, that child has not inherited that familial Lynch syndrome cause and cannot pass it to children. Their cancer screening may still be influenced by unrelated personal history or risk factors.

An uninformative negative occurs when no family mutation is known. The laboratory may find no EPCAM deletion, but another mismatch repair gene could be involved, the assay may not detect a complex breakpoint, or the family clustering may have another cause. A negative EPCAM-only test should not close a broader hereditary colorectal cancer assessment.

A VUS should not be treated as a positive result. Structural variants near gene boundaries can be difficult to interpret, particularly if they do not remove the established critical 3′ region or if their effect on MSH2 methylation is unknown. The laboratory may seek RNA, methylation, segregation, or breakpoint evidence. Management should remain based on personal and family history until classification changes.

Cancer Risks and Surveillance

EPCAM-associated Lynch syndrome is most clearly linked to colorectal cancer. Published families suggest colorectal risk can resemble MSH2-associated Lynch syndrome, although estimates are less precise because EPCAM deletions are rare. Cancer risk varies with the deletion’s boundaries, sex, family history, and whether MSH2 is directly involved.

Endometrial and other extracolonic cancer risks may be lower for deletions limited to EPCAM than for classic MSH2 pathogenic variants. The proposed explanation is tissue-specific EPCAM expression: MSH2 silencing occurs mainly where EPCAM is active. However, risk is not zero, and deletions extending into MSH2 may produce a broader MSH2-like cancer spectrum. Management should follow the exact variant and specialist guidance rather than a general statement that EPCAM is “lower risk.”

Lynch syndrome cancers can include colorectal, endometrial, ovarian, gastric, small-bowel, urinary tract, pancreatic, biliary tract, prostate, brain, and sebaceous skin tumors. Not every carrier needs every possible screening test. Surveillance is prioritized according to the gene, sex, age, family pattern, and evidence that screening improves outcomes.

Colonoscopy is the central preventive measure. Many guidelines recommend starting in early adulthood and repeating every one to two years, with exact starting age individualized by gene and family history. Colonoscopy is preferred over stool testing because Lynch-associated tumors can develop relatively quickly and because polyps can be removed during the procedure.

People with a uterus should discuss endometrial symptoms and risk-reducing options. Abnormal uterine bleeding, bleeding after menopause, or unexplained changes in bleeding pattern require prompt evaluation. Evidence that routine ultrasound or endometrial biopsy reduces mortality is limited, so counseling often emphasizes symptom awareness and discussion of risk-reducing hysterectomy after childbearing. Ovarian risk and removal of the ovaries should be considered separately because risk differs by gene and premature menopause has important health effects.

Other measures may include upper gastrointestinal surveillance in selected people, urinalysis or urinary tract assessment when family history is strong, dermatologic examination for sebaceous tumors, and discussion of aspirin chemoprevention. Aspirin dose and timing should be individualized because bleeding risk, age, other medicines, and evidence continue to evolve.

A pathogenic result can also affect treatment of an existing cancer. Mismatch repair-deficient or MSI-high tumors may be eligible for immune checkpoint therapy in appropriate settings. Surgical planning for colorectal cancer may consider the risk of a second primary tumor. These decisions require an oncology team and should not be made from germline status alone.

Family Testing and Reproductive Options

EPCAM-associated Lynch syndrome is usually autosomal dominant. Each child of a carrier has a 50% chance of inheriting the deletion. Full siblings also have a 50% chance when one parent is known or presumed to carry it. More distant relatives may be at risk through the same side of the family.

Cascade testing uses the exact familial deletion. It is more accurate and efficient than ordering a broad panel for every relative. Adult relatives should receive a copy of the original report and a family letter that explains how to access genetic counseling. Testing minors is generally deferred because routine Lynch syndrome surveillance usually begins in adulthood, unless the family has unusually early cancers or another condition changes the timing.

A positive relative can begin surveillance before symptoms appear. A negative relative can avoid Lynch-specific procedures tied to that familial deletion. This is one of the clearest benefits of germline testing: it separates relatives who inherited the risk from those who did not.

Family communication can be difficult. Privacy laws usually prevent a clinic from contacting relatives directly without permission. The tested person may need support deciding whom to tell, how to explain the result, and how to handle relatives who do not want testing. Genetic counselors can prepare concise letters and identify testing resources in other regions.

Reproductive options include natural conception with testing during pregnancy, in vitro fertilization with preimplantation genetic testing for a monogenic condition, use of donor eggs or sperm, adoption, or choosing not to test. These are personal choices. A PGT-M overview can explain how embryos are tested for a known familial deletion, but an experienced reproductive genetics laboratory must first design a family-specific assay.

Rarely, if both parents carry pathogenic variants affecting the same mismatch repair pathway, a child may be at risk for constitutional mismatch repair deficiency, a severe childhood cancer syndrome. EPCAM deletions usually act through MSH2 silencing in specific tissues, so counseling about this rare possibility should be individualized by the exact variants in both parents.

Limitations and Next Steps

EPCAM testing can fail to answer the clinical question when the wrong method is used. A report that lists only “EPCAM sequencing” without deletion and duplication analysis is incomplete for the established Lynch mechanism. The ordering clinician should verify the assay’s copy-number coverage and whether it examines the terminal exons and EPCAM-MSH2 boundary.

Complex rearrangements can exceed the resolution of a routine panel. A suspected deletion may require MLPA, microarray, long-read sequencing, breakpoint PCR, or another confirmatory method. Results can also differ between laboratories because genomic coordinates, transcripts, and classification criteria vary.

Tumor testing has its own limitations. Loss of MSH2 and MSH6 is suggestive but not proof of a germline EPCAM or MSH2 alteration. Two acquired MSH2 mutations can create the same staining pattern. Conversely, retained staining does not absolutely exclude Lynch syndrome. Paired tumor-germline testing can help resolve “Lynch-like” cases, but it may reveal uncertain findings that require expert review.

After a pathogenic result, the next steps are practical:

1. Confirm that the report describes a pathogenic or likely pathogenic deletion and record its exact boundaries.
2. Meet with a genetics professional to build a three-generation family history.
3. Establish a colonoscopy schedule with a clinician experienced in Lynch syndrome.
4. Review sex- and organ-specific surveillance and risk-reducing options.
5. Provide targeted testing information to adult relatives.
6. Update the care plan when guidelines, family history, or personal health changes.

People who already have cancer should ensure that germline and tumor results are both available to the oncology team. The germline result addresses inherited risk; the tumor result can influence treatment. They overlap, but they are not interchangeable.

Questions worth asking the laboratory or genetics team include whether the test covered exon-level deletions, whether the deletion extends into MSH2, whether the result explains the tumor immunohistochemistry pattern, and whether relatives should receive targeted testing. Keeping the original report is essential because the exact deletion cannot be reconstructed reliably from a verbal summary.

A negative or uncertain result may still justify enhanced screening when the family history is strong. Risk management should not be reduced solely because EPCAM testing was nondiagnostic. A complete assessment can include other Lynch genes, polyposis genes, tumor testing, and review of nonhereditary risk factors.

Insurance and laboratory authorization can also affect the testing path. A genetics clinic may document the tumor staining pattern, age at diagnosis, and family history to support coverage. When a relative was tested years ago, the original assay may not have included EPCAM deletion analysis; updated testing can be appropriate even if an older “Lynch panel” was reported as negative.

References

• Lynch Syndrome 2021 (Review)
• Diagnosis and management of Lynch syndrome 2022 (Review)
• Identification of Lynch Syndrome 2022 (Review)
• Worldwide prevalence of Lynch syndrome in patients with colorectal cancer: Systematic review and meta-analysis 2022 (Systematic Review)
• Canadian consensus for the assessment and testing of Lynch syndrome 2025 (Guideline)
• Cancer risks in Lynch syndrome carriers: a systematic review and meta-analysis 2025 (Systematic Review)

Disclaimer

An EPCAM deletion result should be interpreted by a genetics professional familiar with Lynch syndrome and structural variants. Surveillance recommendations depend on the exact deletion, age, organs present, personal history, and family history, and they change over time. New rectal bleeding, persistent bowel changes, unexplained anemia, or abnormal uterine bleeding requires medical evaluation rather than waiting for routine screening.