Emerging Concepts in Colorectal Cancer:

Hereditary Non-Polyposis Cancer(Lynch Syndrome)

Short Presentations in Emerging Concepts (SPEC)

Colorectal Cancer:Molecular Pathways

HypermutabilityPathway

ChromosomalInstability Pathway

Molecular pathways in colon cancer

What value is there in recognizing MSI-H colorectal tumors?

1. Prognosis

2. Response to chemotherapy

3. Screen for Lynch Syndrome (HNPCC)

Prognostic significance of MSI-H in sporadic CRC

Gryfe,R et al, NEJM 2000; 342:69-77

Tumor Microsatellite-Instability Status as a Predictor of Benefit from Fluorouracil-Based Adjuvant Chemotherapy for Colon Cancer Ribic, C.R., et al. New Engl J Med 349:247-57 (2003)

Colorectal Cancer:Molecular Pathways

Hypermutability Pathway

Chromosomal Instability Pathway

APC

Lynch

Lynch Syndrome (HNPCC)

• HNPCC – Hereditary Non-Polyposis Colon Cancer– Historically:

• Lynch Syndrome I – restricted to colon

• Lynch Syndrome II – colon and extracolonic sites

• Accounts for 3-4% of all colon cancers• Accounts for 15-20% of MSI tumors

• Inherited predisposition to many different cancers, including colon cancer

Lynch Syndrome: Cardinal Features

• Autosomal dominant inheritance

• Gene penetrance for CRC of 85-90%– Develop CRC at an early age - 45 yrs– Most CRC (70%) proximal to splenic flexure– Multiple CRC’s common - synchronous and

metachronous– Prognosis better than sporadic CRC– Associated pathologic features

• Increased risk for other malignancies

Lynch Syndrome:Extracolonic Tumors

Site Features

Endometrium Second most common

Stomach Older generations

Small bowel Risk 25X in HNPCC

Hepatobiliary tract 5% risk

Ureter and pelvis 14-20% risk

Skin Muir-Torre Syndrome

Pancreas Trend for increase

Brain GBM in some HNPCC (Turcot’s)

Hematologic Case reports

Soft tissue Case reports

Larynx Case report

Lynch Syndrome: Cumulative cancer risk in LS carriers by age 70

Aarnio M, et al, Int J Cancer 1999; 81:214-218.

Site of tumor Finnish population (%) HNPCC families (%)

Colon/rectum 1.6 82

Endometrium 1.3 60

Stomach 0.8 13

Ovary 1.3 12

Bladder, ureter, urethra 0.7 4.0

Brain 0.9 3.7

Kidney 0.8 3.3

Biliary tract, gallbladder 0.2 2.0

Lynch Syndrome:Cumulative cancer risk by age 70

By age 70, the risk for endometrial cancer exceeds that of colon cancer:

Aarnio, M et al, Int J Cancer 1999; 81:214-18

Site Incidence by age 70 in women

Endometrium 60%

Colon 54%

Lynch Syndrome:Pathological features of colorectal cancer

• Poor differentiation

• Increased signet cells

• Medullary features

• Peritumoral lymphocyte infiltration

• Crohn’s like reaction

• Tumor infiltrating lymphocytes (TIL’s)

How to recognize Lynch Syndrome

• Amsterdam Criteria– Clinical guidelines for when to suspect Lynch

Syndrome

• Bethesda Guidelines– Guidelines for when to do MSI testing

• Screen all new colon cancers?

Lynch Syndrome - Amsterdam Criteria II (1999)

• At least three family members with a Lynch Syndrome-associated cancer, two of whom are first-degree relatives.

• At least two generations represented.• At least 1 individual younger than 50 years at diagnosis.• FAP should be excluded.• Tumors should be verified by pathologic examination.

Vasen et al, Gastroenterology 1999;116:1453-56

Revised Bethesda Guidelines for testing colorectal tumors for MSI - 2004

Tumors from individuals should be tested for MSI in the following situations:

1. Colorectal cancer in a patient less than 50 years of age.2. Presence of synchronous, metachronous colorectal, or other HNPCC

associated tumors, regardless of age.3. Colorectal cancer with the MSI-H histology diagnosed in a patient less

than 60 yr.4. Colorectal cancer diagnosed in one or more first-degree relatives with

an HNPCC-related tumor, with one of the cancers being diagnosed under age 50 yr.

5. Colorectal cancer diagnosed in two or more first- or second-degree relatives with HNPCC-related tumors, regardless of age.

Umar, et al., J Natl Cancer Inst 2004; 96:261-8Umar, et al., J Natl Cancer Inst 2004; 96:261-8

Lynch Syndrome:Mismatch repair gene mutations

Gene Frequency in HNPCC

MSH2 ~39%

MLH1 ~32%

PMS1 Rare

PMS2 ~14%

GTBP/MSH6 ~14%

Other ?

Immunohistochemistryfor MMR Protein Expression

MLH1

MSH6

MSH2

PMS2

Loss of expressionDue to mutation Lynch SyndromeDue to methylation Sporadic MSI CRC

Universal screening

Recommendations from the EGAPP Working Group: genetic testing strategies in newly diagnosed individuals with colorectal cancer aimed at reducing morbidity and mortality from Lynch syndrome in relatives

Evaluation of Genomic Applications in Practice and Prevention Working Group

Genetics in Medicine 11:35-41 (2009)

Significance of Lynch Syndrome

1. The patient is at risk for other cancers and needs appropriate surveillance.

2. The patient’s relatives will also be at increased risk if they carry the same mutation, and will need appropriate surveillance.

3. Relatives can be tested to determine their risk, and level of surveillance.

Summary

• MSI-H tumors account for about 20% of all colon cancers.

• Lynch Syndrome tumors account for 15 - 20% of MSI-H colon cancers, and about 4% of all colon cancers.

• MSI-H colon cancers are biologically distinctive in their behavior.

• MSI testing should be performed if indicated by Bethesda Guidelines.

• MSI testing can be performed on fixed tissue.• Patients with MSI-H tumors are candidates for genetic

counseling and further genetic testing.

Selected Resources

Lynch HT, et al. Hereditary nonpolyposis colorectal carcinoma and HNPCC-like families: problems in diagnosis,m surveillance, and management. Cancer .2004 ;100:53-64.

EGAPP Working Group. Recommendations from the EGAPP Working Group: genetic testing strategies in newly diagnosed individuals with colorectal cancer aimed at reducing morbidity and mortality from Lynch syndrome in relatives. Genet Med. 2009 ;11(1):35-41.

Vasen HF, Blanco I, Aktan-Collan K, et al. Revised guidelines for the clinical management of Lynch Syndrome (HNPCC): recommendations by a group of European experts. Gut. 2013;62(6):812-823.

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