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Year 3 - Geriatrics and Genetics > Genetic predisposition to cancer > Flashcards

Genetic predisposition to cancer Flashcards

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1
Q

How Much Breast Cancer Is Hereditary?

A

Hereditary = 5-10%

Family clusters = 15-20%

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2
Q

How Much Ovarian Cancer Is Hereditary?

A

5-10%

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3
Q

Causes of hereditary colorectal cancer?

A

1) Familial = 10-30%
2) Lynch syndrome (Hereditary nonpolyposis colorectal cancer, HNPCC) = 5%
3) Familial adenomatous polyposis (FAP) = 1%
4) Rare CRC syndormes = 0.1%

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4
Q

Which type of mutation is heritable?

A

Germline mutations

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5
Q

Which type of mutation is non-heritable?

A

Somatic mutations

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6
Q

Which type of mutation leads to all cells being affected?

A

Germline mutation

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7
Q

Which type of mutation leads to a particulate site being affected?

A

Somatic mutation

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8
Q

Which type of mutation leads to cancer family syndromes?

A

Germline mutation

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9
Q

Which type of mutation is inherited from single alteration in egg or sperm?

A

Germline mutation

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10
Q

Which part of the cell cycle are oncogenes?

A

Between G1 (cell growth) and G0 (Resting)

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11
Q

Which part of the cell cycle are tumour suppressor genes?

A

Between G0 (Resting) and S (Synthesis)

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12
Q

Which part of the cell cycle are DNA repair genes?

A

Between S (Synthesis) and G2

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13
Q

Which oncogene is linked to Leukaemia?

A

Oncogene ABL - ACR-ABL Fusion protein

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14
Q

What is the oncogene BCR-ABL linked to?

A

CML and ALL

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15
Q

What is the tumour suppressor gene Rb linked to?

A

Retinoblastoma and osteosarcoma

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16
Q

How does an oncogene work?

A

1) Needs damage to only one allele

2) Leads to a gain of function

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17
Q

How does an tumour suppressor gene work?

A

1) Needs damage to both (two) alleles

2) Leads to loss of function

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18
Q

1st mutation/loss versus 2nd mutation/loss in tumour supressor genes?

A 
1st = Susceptible carrier
2nd = Leads to cancer
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19
Q

Multi-step carcinogenesis of colon cancer?

A

1) Loss of APC = Hyper-proliferative epithelium and then Early adenoma
2) Activation of K-ras = Intermediate adenoma
3) Loss of 18q = Late adenoma
4) Loss of TP53 = Carcinoma
5) Other alterations = Metastasis

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20
Q

What does mutation/loss of APC tumour suppressor gene lead to ?

A

Coloractal cancer (Associated with FAP)

21
Q

What does activation of K-Ras oncogene lead to?

A

> Colorectal cancer
Lung cancer
Pancreatic cancer

22
Q

What does loss/mutation of TP53 tumour suppressor gene lead to?

A

> Most human cancers

> Li-Fraumeni syndrome

23
Q

What is the main mechanism for familial cancer?

A

Faulty DNA mismatch repair

24
Q

What is Lynch syndrome (Hereditary non-polyposis colon cancer) caused by?

A

Mutation in mismatch repair genes

25
Q

Where is the tumour site usually in Lynch syndrome (HNPCC)?

A

Proximal colon

26
Q

What is the common age of diagnosis in Lynch syndrome/HNPCC related colorectal cancer?

A

Early but variable (45 years)

27
Q

Which types of cancers caused by Lynch syndrome/HNPCC?

A

1) Colon (78%)
2) Endometrial (60%)
3) Stomach (19%)
4) Biliary tract (18%)
5) Ovarian (11%)
6) Urinary tract (10%)
7) Sebaceous gland (9%)
8) CNS (4%)

28
Q

Within women what is the lifetime risk of breast cancer in BRCA1 and BRCA2 tumour suppressor genes?

A

1) Breast cancer (60-80%) - Often early age at onset

2) Second primary breast cancer (40-60%)

29
Q

Within women what is the lifetime risk of ovarian cancer in BRCA1 and BRCA2 tumour suppressor genes?

A

20-50% (BRCA1 increased risk versus BRCA2)

30
Q

Within men what cancers in BRCA1 and BRCA2 tumour suppressor genes are they at risk of?

A

Increased risk of prostate, breast cancer and pancreatic cancer

Especially in BRAC2 mutations/loss

31
Q

In autosomal dominant inheritance what is the chance of a child inheriting the mutation?

A

50% chance in an unaffected individual

32
Q

In autosomal dominant inheritance what is the chance of a skipped generation?

A

There is no skipped generation

33
Q

If a grandmother had an autosomal dominant condition and the mother of the grandson wasn’t affected by the mutation what is the chance of the grandson being a carrier?

A

25%

34
Q

When should inheritors cancer syndrome be suspected?

A

> Cancer in 2 or more close relatives (on same side of family)

> Early age at diagnosis

> Multiple primary tumors

> Bilateral or multiple rare cancers

> Characteristic pattern of tumours (e.g. breast and ovary)

> Evidence of autosomal dominant transmission

35
Q

What is the cancer genetics process?

A

1) Obtain family history
2) Confirm diagnosis of cancer
3) Risk estimation
4) Counselling

36
Q

Aspects of clinical genetics consultation?

A

1) Family history
2) Risk estimation
3) Explanation of basis of risk

4) Interventions:
- Increased awareness of symptoms/signs
- Lifestyle = Diet, smoking, exercise
- Prevention = Oestrogen, aspirin use
- Screening
- Prophylactic surgery

5) Genetic testing

37
Q

Surveillance option is breast cancer?

A

Early clinical surveillance (Mammography):

  • Moderate/High = 2 yearly from 35-40yrs and yearly 40-50yrs
  • High = 18 months
38
Q

What is the option in BRCA1 and BRCA2 carriers?

A

Prophylactic mastectomy - In BRCA1 mutation positive women incidence is reduced to 5%

Prophylactic Oophorectomy

39
Q

What is the advantage of prophylactic oophorectomy in BRCA1/BRCA2 carriers?

A

1) Eliminates risk of primary ovarian cancer; however; peritoneal carcinomatosis may still occur
2) Risk of subsequent BRCA halved

40
Q

What is the advantage of laparoscopic oophorectomy in BRCA1/BRCA2 carriers?

A

Laparoscopic approach reduces postsurgical morbidity

41
Q

Which drug may be given prophylactically in high risk individuals for colorectal cancer?

A

Aspirin

42
Q

When an individual is a gene carrier for colorectal cancer when should screening be carried out?

A

Colonoscopy should be performed every 2 years from 25 years old

43
Q

When an individual is a moderate risk for colorectal cancer when should screening be carried out?

A

Colonoscopy should be performed every five years from 50yrs or yearly from 55yrs

44
Q

How can you genetically test for Lynch syndrome?

A

IHC for mismatch repair gene proteins or micro satellite instability testing (MSI)

45
Q

What are the benefits of genetic testing?

A

> Identifies highest risk

> Identifies non-carriers in families with a known mutation

> Allows early detection and prevention strategies

> May relieve anxiety

46
Q

What are the risks/limitations of genetic testing?

A

> Does not detect all mutations

> Continued risk of sporadic cancer

> Efficacy of interventions variable

> May result in psychosocial
or economic harm

47
Q

In terms of family history who is important to test in hereditary disease?

A

1st degree relatives = Father, mother, siblings and children

2nd degree relatives = Aunt, uncle, grandparents

3rd degree relatives = First cousin

48
Q

Which mutation is associated with Li-Fraumeni syndrome?

A

TP53 tumour suppressor gene mutation/loss

Year 3 - Geriatrics and Genetics (10 decks)

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