HEREDITARY BREAST CANCER IN DEVELOPING COUNTRIES

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HEREDITARY BREAST CANCER IN DEVELOPING COUNTRIES

• Prof. Richard Pestell
• Prof. Jan Lubinski
• Prof. T.Rajkumar

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QUESTIONS TO BE DISCUSSED

• What is cancer genetic counseling?
• Issues related to setting up a Hereditary cancer
  programme in a developing country?
• Socio-economic issues in India and in the West.
• Financial implications in testing.
• Guidelines in gene testing
• What could be the take home message.

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Assessing the Genetic Risks of Cancer

• If the family history reveals one or more of the
  following features, then a further assessment is
  warranted
• cancer in two or more close relatives
• multiple primary tumors in the same individual
• bilateral cancer in paired organs
• an earlier-than-usual onset of cancer
• a specific constellation of tumors that comprise
  a known cancer syndrome
• If one of these features are found in the
  individual's own or family history, familial or
  hereditary factors should be considered and
  further evaluated.

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Cancer Risk Counseling

• In contrast to "traditional" genetic counseling,
  which often focuses on reproductive risks, those
  seeking cancer risk counseling are usually at an
  increased risk of developing cancer themselves.
• Therefore, much of the discussion and focus of
  cancer risk counseling concerns the individual's
  personal risk of developing a disease.

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Cancer Risk Counseling

• Thus, those who provide cancer risk counseling
  should
• emphasize prevention of cancer,
• convey recommendations for surveillance,
• discuss life-style modifications that may reduce
  the risk of developing cancer, and
• provide an assessment of risk to the individual
  and other family members.
• Gene testing implications of a positive,
  negative or uninformative test result

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Assessing the Genetic Risks of Cancer

• The two major decision points in the assessment
  of cancer risk are
• Is the risk of cancer higher or lower than in the
  general population?
• Is the risk higher or lower than that perceived
  by the patient?

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Assessing the Genetic Risks of Cancer

• The family history questionnaire provides the
  initial information to answer the first
  questionindividuals with negative family
  histories and minimal family concerns should be
  counseled as such, putting their concerns in the
  context of the general population risk. Cancer
  screening and prevention information are probably
  all that is needed.

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Assessing the Risks of Hereditary Cancer
Syndromes

• Although the specific genes involved in several
  hereditary cancer syndromes have been discovered,
  the initial identification of families with these
  syndromes is based on clinical and family history
  criteria.
• Hereditary cancer syndromes follow Mendelian
  inheritance patterns...usually autosomal dominant
  with reduced penetrance and variable
  expressivity.

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PENETRANCE AND EXPRESSIVITY

• The parent transmitting the gene did not show the
  trait, even though he or she carried the allele
  this is known as incomplete penetrance, that is,
  the inconsistent phenotypic expression of a gene
  even though the gene is present.
• The parent of the affected individual expressed
  the gene but in ways that were not readily
  recognized this is known as variable
  expressivity.

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MATERIALS
Hereditary breast and ovarian cancer study
Total number of cases studied 80 Hereditary
Breast Cancer Families - 26 Hereditary Breast and
Ovarian Cancer Families - 15 Hereditary Ovarian
Cancer Families - 3 Breast and Ovarian Cancer
cases - 3 Early onset Breast Cancer cases -
29 Early onset Ovarian Cancer cases -
3 Hereditary Prostate and Breast Cancer families
-1
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CRITERIA FOR GENETIC TESTING

• HBOC STUDY
• Early onset of breast cancer ( at or less than 35
  years of age).
• Two cases of breast cancer diagnosed under the
  age of 50 years.
• Three cases of breast cancer diagnosed under 60
  years of age.

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CRITERIA FOR GENETIC TESTING

• Four or more cases of breast cancer diagnosed at
  any age.
• Presence of breast and ovarian cancer in the
  family or in the same individual.
• Male breast cancer with a relative (of either
  sex) with breast cancer.

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DHPLC

• Reverse phase ion exchange chromatography
• DHPLC analysis All fragments analyzed at a
  basal temperature of 50C plus two or more higher
  partial denaturing temperatures.
• The DHPLC systems performance was validated with
  pUC18 HaeIII digest once every 200 runs.

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DHPLC
dHPLC Unit
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METHODS - SEQUENCING

• Cycle sequencing was done with both forward and
  reverse primers in separate reaction and run in
  ABI 310 Genetic Analyzer.
• The sequences were analyzed in Sequence Analysis
  v 3.4.1.
• For the samples that showed mutation, DNA from
  fresh aliquot of lymphocytes was used to sequence
  again to confirm the results.

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RESULTS
HEREDITARY BREAST AND OVARIAN CANCER STUDY

• No of women with breast/ovarian cancer studied
  - 80
• No of controls studied - 1
• No of disease causing mutation detected
  - 12/80 (15)
• No of variants of unknown significance detected
  - 1/80 (1.2)
• No of samples wherein polymorphisms detected -
  77/80 (96)
• No of samples with no polymorphisms in BRCA1 -
  20/80 (25)
• No of samples with no polymorphisms in BRCA2 -
  10/80 (12.5)

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CASE -1
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CASE-II
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CASE-III
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CASE-IV
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CASE-V
22
CASE-VI
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CASE-VII
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CASE-VIII
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CASE-IX, X, XI, XII
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CASE-IX, X, XI, XII
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CASE-IX, X, XI, XII
Frame shift mutation
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CASE-XIII- UNKNOWN SIGNIFICANCE
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RESULTS ON MUTATION ANALYSIS
BRCA1 and BRCA2 analysis was done for 80 cases
Number of HBOC cases that showed pathogenic mutation 8/45 (17.8)
Number of HOC cases that showed pathogenic mutation 1/3 (33.3)
Number of early onset breast cancers that showed pathogenic mutation 3/29 (10.3)
Number of early onset ovarian cancers that showed pathogenic mutation 0/3 (0)
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Common Polymorphisms Detected in BRCA1in the
exonic region
Polymorphisms Percentage
11K - c.3311TgtC p.L771L 42/80 (52.5)
11N - c.2612CgtT p.P871L 38/80 (47.5)
11S - c.3113AgtG p.E1038G 20/80 (25)
11TU - c.3548AgtG p.K1183R 12/80 (15)
16 - c.4954AgtG p.M1652I 4/80 (5)
16 - c.4839GgtA p.S1613G 4/80 (5)
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Common Polymorphisms Detected in BRCA2 in the
exonic region
Polymorphisms Percentage
10B - c.1114CgtA p.H372N 35/80 (43.8)
11B - c.4258GgtT p.D1420Y 2/80 (2.5)
11C - c.4779AgtC p.E1593D 1/80 (1.25)
11F - c.2538AgtC p.S846S 2/80 (2.5)
11H - c.2892AgtT p.K964N 1/80 (1.25)
11I - c.2971AgtG p.N991D 5/80 (6.25)
11K - c.3807TgtC p.V1269V 4/80 (5)
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Common Polymorphisms Detected in BRCA1in the
intronic region
Polymorphisms Percentage
c.301-41TgtC 5/80 (6.25)
c.441-34TgtC 1/80 (1.25)
c.548-58del T 22/80 (27.5)
c.4184-10GgtA 1/80 (1.25)
c.4987-68AgtG 22/80 (27.5)
c.4987-92AgtG 22/80 (27.5)
c.507566GgtA 5/80 (8.1)
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Common Polymorphisms Detected in BRCA2 in the
intronic region
Polymorphisms Percentage
c.1-26GgtA 4/80 (5)
c.684179delTTAA 32/80 (40)
c.7807-14TgtC 40/80 (50)
c.8755-66TgtC 39/80 (48.8)
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QUESTIONS TO BE DISCUSSED

• What is cancer genetic counseling?
• Issues related to setting up a Hereditary cancer
  programme in a developing country?
• Socio-economic issues in India and in the West.
• Financial implications in testing.
• Guidelines in gene testing
• What could be the take home message.