Genetic Predisposition to Cancer Flashcards

1
Q

Mutations cause faulty proteins, what are the possibilities?

A
  • Functional protein
  • Non-functional or missing protein
  • Protein with reduced function
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2
Q

What does cancer arise from?

A

Gene mutations

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3
Q

Describe the cell cycle?

A
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4
Q

What are oncogenes?

A

Oncogenes = regulate cell growth

  • A mutation of oncogenes leads to accelerated cell division, and ultimately maybe cancer
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5
Q

What are tumour suppresor genes?

A

Tumour suppressor genes = normal genes that slow down cell division, repair DNA mistakes or tell cells when to die

  • 1st mutation makes you susceptible to cancer
  • 2nd mutation leads to cancer
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6
Q

Describe the pathogenesis of cancer, using colon cancer as an example?

A
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7
Q

What is the main mechanism for familial cancer?

A

Faulty DNA mismatch repair

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8
Q

Is familial cancer autosomal dominant or recessive?

A

Is autosomal dominant inheritance:

  • Each child has 50% chance of inheriting mutation
  • No skipped generations
  • Equally transmitted by men and woman
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9
Q

What is Lynch syndrome/HNPCC?

A

Is a mutation in mismatch repair genes:

  • Excess of colorectal, endometrial, urinary tract, ovarian and gastric cancer
  • Adenoma-carcinoma sequence for polyp formation
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10
Q

What cancers does Lynch syndrome/HNPCC increase risks of?

A

Excess of colorectal, endometrial, urinary tract, ovarian and gastric cancer

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11
Q

What are clinical features of lynch syndrome/HNPCC?

A
  • Early but variable age of diagnosis
  • Tumour site in proximal colon predominates
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12
Q

What investigations are done for lynch syndrome/HNPCC?

A
  • Genetic testing
    • IHC for mismatch repair gene proteins
    • Or microsatellite instability testing (MSI)
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13
Q

What is Lynch syndrome also known as?

A

Hereditary non-polyposis colorectal cancer (HNPCC)

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14
Q

When should you suspect hereditary cancer syndrome?

A
  • Cancer in 2 or more close relatives
  • Early age of diagnosis
  • Multiple primary tumours
  • Bilateral or multiple rare cancers
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15
Q

Describe the cancer genetics process at the clinic?

A
  • Detailed family history
    • Verbally reported pedigree and then revised pedigree based on pathology reports
  • Confirm diagnosis of cancer
  • Risk estimation
    • Genetic centres can classify people as gene carrier who is high, medium or low risk (low risk being similar to population average)
  • Interventions
    • Awareness of symptoms/signs
    • Lifestyle – diet, smoking, exercised
    • Prevention – oestrogen, aspirin
    • Screening
    • Prophylactic surgery
  • Genetic testing
    • Consider in high risk
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16
Q

What interventions can be done for people with increased risk of cancer?

A
  • Awareness of symptoms/signs
  • Lifestyle – diet, smoking, exercised
  • Prevention – oestrogen, aspirin
  • Screening
  • Prophylactic surgery
17
Q

What are the benefits and risks of genetic testing?

A
18
Q

What cancers are associated with BRCA1/2 mutations?

A
  • Breast cancers 60-80%
    • Second primary breast cancer 40-60%
  • Ovarian cancer 20-150%
  • In males, increased risk of prostate and breast cancer
19
Q

What are options for breast cancer surveillance?

A
  • Breast awareness
  • Early clinical surveillance
    • Annual clinical breast exams
    • Mammography
      • Indications – moderate/high risk
      • 2 yearly from 35-40 then yearly from 40-50
    • MR
      • Indications – those at highest risk
20
Q

How often do people with BRCA1/2 mutations get a mammograph?

A
  • 2 yearly from 35-40 then yearly from 40-50
21
Q

Describe the management of BRCA1/2 mutations?

A
  • Prophylactic mastectomy
    • Removes most but not all breast tissue
    • Massively reduces risk
    • Total mastectomy removes more breast than subcutaneous mastectomy
  • Prophylactic oophorectomy
    • Eliminates risk of ovarian cancer
    • Complications – surgical menopause
22
Q

What is done for colorectal cancer surveillance for those at risk due to gene mutations?

A

Colonoscopy:

  • 2 yearly from ages 25 to 35 if gene carrier
  • 5 yearly from 50 if moderate risk
23
Q

Who are 1st, 2nd and 3rd degree relatives?

A