Genetic changes in endometrial cancer and HNPCC syndrome

DR.ASHISH POKHARKAR(Tata memorial hospital)

“An individual doesn't get cancer…..,A family does”TERRY TWMPEST WILLIAMS

sporadic 90%

hereditary, 10%

Ta b l e 1 : C l i n i c a l A nd Pa t ho l og i c a l Fe a t u re s O f E ndo m e t r i a l C a rc i no m a .

Ty p e I ( E E C ) Ty p e I I ( N E E C )

A g e P r e - A n d P e r i m e n o p a u s a l P o s t m e n o p a u s a l

B e h a v i o u r S t a b l e P r o g r e s s i v e

G r a d e L o w ( s t a g e I , I I ) H i g h ( S t a g e I I I / I V )

H y p e r p l a s i a - p r e c u r s o r P r e s e n t A b s e n t

U n o p p o s e d O e s t r o g e n P r e s e n t A b s e n t

M y o m e t r i u m I n v a s i o n M i n i m a l D e e p

S p e c i f i c S u b t y p e s E n d o m e t r i o i d C a r c i n o m a N o n - e n d o m e t r i o i d

C a r c i n o m a

P r e v a l e n c e 7 0 – 8 0 % 1 0 – 2 0 %

R i s k F a c t o r s O b e s i t y , A n o v u l a t i o n , I n A t r o p h i c E n d o m e t r i u m

N u l l i p a r i t y A n d E x o g e n o u s O e s t r o g e n E x p o s u r e

TABLE 2. MOLECULAR FEATURES OF ENDOMETRIAL CARCINOMA

EEC(TYPE I) NEEC( TYPE II)

GAIN-OF FUNCTION

  K-RAS 15–30% 0–5%

  HER2/NEU 10–20% 9–30%

  B-CATENIN 31–47% 0–3%

LOSS-OF FUNCTION

  PTEN 35–50% 10%

  P53 10–20% 90%

  GENOMIC INSTABILITY 20–40% 0-5%

(MICROSATELLITE)

LYNCH SYNDROME

HISTORY

Father of hereditary cancer.

Henry T. Lynch (professor of medicine at Creighton University Medical Centre) characterized the syndrome in 1966.

The term "Lynch syndrome" was coined in 1984 by other authors, and Lynch himself coined the term HNPCC in 1985.

WHAT IS LYNCH SYNDROME?

Autosomal dominant inheritance associated with mutation in mismatch repair genes(MLH1,MSH2,MSH6,PMS2).

Increased risk of colon cancer and other extra colonic sites. E.g. endometrium,ovary,stomach,renal pelvis,ureter,small bowel etc.

Lynch syndrome type I – Familial colon cancer

Lynch syndrome type II – familial colon cancer with cancers of extra colonic sites

Muir –torre variant – with sebaceous adenoma, sebaceous carcinoma and multiple keratocanthomas.

Turcot syndrome-colorectal cancer or colorectal adenomas in addition to tumours of the central nervous system.

SALIENT FEATURES

Earlier age of onset.( 45 Vs. 63 yrs. for colonic cancers, 47 Vs. 60 yrs. for endometrial cancer).

Proximal colonic cancer predisposition ( 75-80%).

Accelerated carcinogenesis, ( 2-3 yrs. vs. 8-10 yrs.).

High risk of synchronous and metachronous tumors.

Pathology of colonic cancer is more often poorly differentiated with excess of mucoid and signet cell features with Crohn’s like reaction and lymphocytes infiltration.

CANCER RISKS IN INDIVIDUALS WITH LYNCH SYNDROME AGE ≤70 YEARS COMPARED TO THE GENERAL POPULATION

Cancer Type General Population Risk

Lynch Syndrome(MLH1 and MSH2 heterozygotes)

Risk Mean Age of Onset

Colon 5.5% 52%-82% 44-61 years

Endometrium 2.7% 25%-60% 48-62 years

Stomach <1% 6%-13% 56 years

Ovary 1.6% 4%-12% 42.5 years

Hepatobiliary tract <1% 1.4%-4%% Not reported

Urinary tract <1% 1%-4% ~55 years

Small bowel <1% 3%-6% 49 years

Brain/central nervous system <1% 1%-3% ~50 years

Sebaceous neoplasms <1% 1%-9% Not reported

COLON CANCER

2/3 Cancers in proximal colon.

Better prognosis than sporadic colon cancers.(When matched stage for stage)

Histologic characteristics: poor differentiation, tumor-infiltrating lymphocytes, mucin, and signet ring or cribiform histology

ENDOMETRIAL CANCER

25%-60% lifetime risk of endometrial cancer.

Average age of diagnosis of appr. 48 years.

Among women with lynch syndrome who develop both colon cancer and endometrial cancer, approximately 50% present first with endometrial cancer.

The risk for subsequent endometrial cancer for women with lynch syndrome presenting first with colon cancer has been estimated at 26% within ten years of the initial colon cancer diagnosis.

According to study by Westin et al 1/3 of lower uterine segment tumors are associated with lynch syndrome.

Endometroid histology is most common.

OVARIAN CANCER

The mean age of diagnosis of Lynch syndrome-associated ovarian cancers is 42.5 years.

Endometroid histology is most common type.

Overall 4-12% lifetime risk.

PATHOGENESIS & MOLECULAR GENETICS

Mutations in the genes of mismatch repair pathways.

MSH2 2p21 DNA mismatch repair protein Msh2

PMS1 2q32 .2 PMS1 protein homolog 1

PMS2 7p22 .1 Mismatch repair endonuclease PMS2

MSH6 2p16 .3 DNA mismatch repair protein Msh6

MLH1 3p22 .2 DNA mismatch repair protein mlh1

EPCAM 2p21 Epithelial cell adhesion molecule

MICROSATELLITE INSTABILITY

DIAGNOSIS

How can we improve identification of LS??

Adequate education of general population.

Adequate family history.

Use of surveillance criteria.

Amsterdam criteria

Amsterdam II criteria

Revised bethesda guidelines.

AMSTERDAM CRITERIA

Amsterdam Criteria  Amsterdam II Criteria 

Three or more family members, one of whom is a first-degree relative of the other two, with a confirmed diagnosis of colorectal cancer

Two successive affected generations

One or more colon cancers diagnosed before age 50 years

Exclusion of familial adenomatous polyposis (FAP)

Three or more family members, one of whom is a first-degree relative  of the other two, with HNPCC-related cancers 

Two successive affected generations

One or more of the HNPCC-related cancers diagnosed before age 50 years

Exclusion of familial adenomatous polyposis (FAP)

REVISED BETHESDA GUIDELINES

Tumours from individuals should be tested for microsatellite instability in the

following situations:

1. Colorectal cancer diagnosed under the age of 50 years of age.

2. Presence of synchronous, metachronous colorectal, or other HNPCC associated

tumours, regardless of age.

3. Colorectal cancer with the MSI-H histology diagnosed in a patient who is

less than 60 years of age.

4. Colorectal cancer diagnosed with one or more first-degree relatives with an

HNPCC-related tumour, with one of the cancers being diagnosed under age 50

years.

5. Colorectal cancer diagnosed in two or more first or second degree relatives

RECENT GUIDELINES BY MALLOCRA GROUP

Testing all CRC and all EC (or individuals <70yrs) by IHC or MSI is useful for the identification of patients with LS (category of evidence IIb).

1) Recommends investigation of all CRC (or individuals with CRC<70 years) by IHC of the four MMR proteins or MSI (grade of recommendation C).

These tests should be accompanied by methods that identify MLH1 promoter methylation.

2) Investigation of all EC in individuals less than 70 years by IHC or MSI can be considered to improve identification (grade of recommendation C).

(Revised Guidelines for the Clinical Management of Lynch Syndrome (HNPCC) Recommendations by a Group of European Experts Hans F A Vasen, Ignacio Blanco, Katja Aktan-Collan, Jessica P Gopie, Angel Alonso, Stefan Aretz, Inge Bernstein, Lucio Bertario, John Burn, Gabriel Capella, Chrystelle Colas, Christoph Engel, Ian M Frayling, Maurizio Genuardi, Karl Heinimann, Frederik J Hes, Shirley V Hodgson, John A Karagiannis, Fiona Lalloo, Annika Lindblom, Jukka-Pekka Mecklin, Pal Møller, Torben Myrhoj, Fokko M Nagengast, , Yann Parc, Maurizio Ponz de Leon, Laura Renkonen-Sinisalo, Julian R Sampson, Astrid Stormorken, Rolf H Sijmons, Sabine Tejpar, Huw J W Thomas, Nils Rahner, Juul T Wijnen, Heikki Juhani Järvinen, Gabriela Möslein Gut. 2013;62(6):812-823)

TESTS USED FOR SCREENING AND DIAGNOSIS

TESTS USED ON TUMOR TISSUE

Used to establish probability of lynch syndrome.

Tissue type: Generally done on colorectal tumor tissue, polyp can be used.

Testing can be done on endometrial cancer tissue.

Two types of tests: 1) Immunohistochemistry (IHC)

2) Microsatellite instability (MSI) testing

IMMUNOHISTOCHEMISTRY

IHC detects the presence or absence of the protein products expressed by mismatch repair genes.

The MMR gene products work in dimers:

MSH2 complexes MSH6 / MSH3 protein,

MLH1 complexes with PMS2/ PMS1 protein.

MSH6 and PMS2 proteins are unstable when not paired in a complex;

thus, a germline mutation in

MSH2 typically results in loss of expression of the proteins MSH2/MSH6

MLH1 results in loss of expression of the proteins MLH1/PMS2.

However, germline mutations in MSH6 and PMS2 typically do not result in loss of MSH2 or MLH1 expression because these proteins are still present in other pairings.

ADVANTAGES OF IHC TESTING:

Antibodies for MSH2, MLH1, MSH6, and PMS2 have demonstrated 92% sensitivity for identifying tumors that arise in individuals with a germline mutation .

Readily available at most centres and is technically easy to perform.

IHC testing identifies in most individuals the MMR gene in which either a germline mutation or a somatic alteration that silences gene expression is most likely to be found thus significantly reducing the cost of molecular genetic testing.

DISADVANTAGES OF IHC TESTING:Variation in tissue fixation and other technical issues can result in weak or equivocal staining patterns.

It is possible that some missense germline mutations will not result in the absence of a detectable protein product.

It may be less reliable when performed on small tissue samples.

MSI TESTING

For MSI analysis, DNA is usually extracted from paraffin-embedded tumor tissue and normal tissue or peripheral blood.

Reliable demonstration of MSI requires that at least 30% of the tumor specimen is composed of tumor cells.

PCR is used to amplify the region containing the microsatellite, and the products are then separated on the basis of size. A microsatellite is considered unstable if the distribution of the fragments from the tumor sample differs from that of the normal tissue

A 1997 NCI consensus meeting recommended a core panel of five markers: BAT25, BAT26, D2S123, D5S346, and .D17S250.

MSI-high if more than two (or >30%) of the markers show instability.

MSI-low if one (or <30%) of the markers show instability.

MSI-stable if 0 (or 0%) of the markers show instability.

ADVANTAGES:Effective method, sensitivity 93 %.

MSI testing may be positive (i.e., Identify a tumor as arising from MMR deficiency) when the IHC studies have given a false negative result (e.g., Because the appropriate antibody was not included in the test; the protein is present, but non-functional).

Can be done with very little tissue.

Highly reproducible.

Disadvantages:May not be readily available.

It does not reduce the cost of molecular testing because it does not help identify the gene which is most likely mutated.

MOLECULAR GENETIC TESTING.

Once a tumor is determined to be MSI-H and/or demonstrates loss of MMR protein expression by IHC, the individual can, after appropriate genetic counselling, elect to have molecular genetic testing to identify a germline mutation in one of the MMR genes.

SURVEILLANCE PROTOCOL FOR COLON CANCER.

Regular colonoscopy leads to a reduction of CRC-related mortality and also to a significant reduction of overall mortality in contrast with CRC screening in the general population.

Colonoscopy is recommended rather than flexible sigmoidoscopy because of the predominance of proximal colon cancers in lynch syndrome.

Current recommendations are to have colonoscopy every one to two years beginning between ages 20 and 25 years or ten years before the earliest diagnosis in the family, whichever is earlier.

SURVEILLANCE PROTOCOL FOR ENDOMETRIAL AND OVARIAN CANCERS.

No proven screening strategy.

Patient should be aware that abnormal vaginal bleeding warrant evaluation.

Can consider screening with annual endometrial biopsy and transvaginal ultrasound beginning at age 30.

SURVEILLANCE PROTOCOL FOR STOMACH AND SMALL BOWEL CANCERS.

Currently the NCCN recommends beginning upper endoscopy with a side-viewing scope and extended duodenoscopy between ages 30 and 35 years and repeating them every two to three years depending on the findings.

At this time data are limited regarding screening for cancer development in the distal small bowel. Capsule endoscopy every two to three years beginning between ages 30 and 35 years can be considered.

SURVEILLANCE PROTOCOL FOR UROTHELIAL CANCERS

NCCN recommends consideration of annual urine analysis starting at age 25-30.

RISK REDUCING STRATEGIES:

Prophylactic removal of the uterus and ovaries (prior to the development of cancer) can be considered after childbearing is completed.

Can consider chemoprevention with OCP and progestins.

Because routine colonoscopy is an effective preventive measure for colon cancer, prophylactic colectomy is generally not recommended for individuals with Lynch syndrome.

Regular aspirin significantly reduces the incidence of cancer in LS.

MANAGEMENT:

If colon cancer is detected, full colectomy with ileorectal anastomosis is recommended rather than a segmental/partial colonic resection because of the high risk for metachronous cancers.

The other tumors seen in Lynch syndrome are managed as in the general population.

EVALUATION OF RELATIVES AT RISK

When an MMR gene mutation has been identified in a family with Lynch syndrome, molecular genetic testing for the mutation should be offered to all first-degree relatives (parents, sibs, and children).

GENETIC COUNSELLING

Genetic counselling is the process of providing individuals and families with information on the nature, inheritance, and implications of genetic disorders to help them make informed medical and personal decisions.

RISK TO FAMILY MEMBERSNot all individuals with a Lynch syndrome-causing MMR gene mutation have a parent who had cancer.

if clinical and family history cannot identify from which parent the proband inherited the MMR gene mutation, molecular genetic testing should be offered to both parents to determine which one has the mutation identified in the proband.

Molecular genetic testing for the mutation identified in the family should be offered to all sibs.

Each child of an individual with Lynch syndrome has a 50% chance of inheriting the mutation.

GENETIC COUNSELLING ISSUES

Family planning: It is appropriate to offer genetic counselling (including discussion of potential risks to offspring and reproductive options) to young adults who are affected or at risk.

Molecular genetic testing of asymptomatic individuals younger than age 18 years should not be advised.

Prenatal Testing

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