Lab Diagnosis of Cancer Flashcards

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1
Q

What is the gold standard for cancer diagnosis?

A

Histology

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2
Q

What proportion of cases show histological features at either end of the benign-malignant spectrum?

A

The majority

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3
Q

What produces problems of diagnosis and management?

A

The small number of cases that sit in the middle of the spectrum that are difficult to classify

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4
Q

What types of tissue samples are sent for cancer diagnosis?

A
  • Diagnostic biopsy (incisional/needle core)

- Excisional specimen (can be done with curative intent)

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5
Q

What types of cytology samples are sent for cancer diagnosis?

A
  • Exfoliative (scraped or shed cells)

- Fine needle aspiration +/- US guidance

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6
Q

What samples can be taken of shed cells?

A
  • Sputum
  • Urine
  • Pleural fluid
  • Ascites
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7
Q

What is the issue with samples of shed cells?

A

Cells degenerate quickly so cancer pick-up rate is low

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8
Q

What samples can be taken of scraped cells?

A
  • Cervical smear

- Bronchial brushings

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9
Q

Why are scraped cells better than shed cells?

A

Cells are intact and viable so cancer pick-up rate higher

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10
Q

When do you take an aspirate?

A

When no surface is available:

  • Accessible lump
  • Breast tissue
  • Lymph node
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11
Q

When is US guidance needed?

A

For an aspirate of an inaccessible lump, the liver or pancreas

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12
Q

How are tissue samples processed?

A

Tissue blocks are impregnated with wax to support the tissue while 4µm sections are cut.
These sections are mounted on a glass slide and stained.

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13
Q

What is the major stain used in histology?

A

H&E (Haemotoxylin and Eosin)

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14
Q

What will a histology report consider? (6)

A
  • Is there a lesion (sampling error)?
  • Is it malignant?
  • What kind of malignancy is it?
  • Grade?
  • Stage?
  • Has it all been removed?
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15
Q

What 2 criteria are taken into consideration when judging if a lesion is malignant?

A
  • Tissue changes

- Cytological changes

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16
Q

What tissue changes are considered when judging malignancy?

A
  • Dysplasia
  • Invasion
  • Infiltrative margin
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17
Q

What cytological changes are considered when judging malignancy?

A
  • Nuclear pleomorphism, size, shape and staining
  • Increased proliferation, number mitotic figures
  • Abnormal mitotic figures
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18
Q

What is judged when classifying the type of malignancy?

A
  • Identifying differentiation (histogenic classification)
  • Molecular classification (esp. with HPV)
  • Architectural arrangement
  • Cytological differentiation
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19
Q

What are the classes of tissues that can be distinguished in histogenic classification?

A
  • Squamous
  • Glandular
  • Lymphoid
  • Melanocytic etc
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20
Q

What can be looked at in cytological differentiation to judge what sort of malignancy is present?

A
  • Morphology

- Protein expression

21
Q

What is the grade of a tumour?

A

How well differentiated it is from the original tissue

22
Q

What does grade indicate?

A

Management and sometimes prognostication

23
Q

What does well differentiated mean?

A

The tumour cells closely resemble the original tissue. Likely to be indolent/less agressive than a poorly differentiated tumour.

24
Q

How is grade assessed?

A
  • Proliferation
  • Architectural differentiation
  • Pleomorphism
25
Q

How is breast cancer graded?

A
Scoring of these categories then add scores up to get a number 3-9:
-Tubule formation
-Pleomorphism
-Mitotic counts
3,4,5=Grade 1
6,7=Grade 2
8,9=Grade 3
26
Q

How is tubule formation graded in breast cancer?

A

1= over 75% tubules
2= 10-75% tubules
3=less than 10% tubules

27
Q

How is pleomorphism graded in breast cancer?

A

1=nuclear size similar to benign
2=large nuclei with open chromatin
3=marked variation in shape and size

28
Q

What is the stage of a cancer?

A

The extent of the tumour’s spread

29
Q

What is staging used for in most cancers?

A

Prognostication mainly and management

30
Q

Where do carcinomas spread to?

A

Lymph nodes

31
Q

Where do sarcomas spread via?

A

The blood stream

32
Q

What is the most common staging system?

A

TNM

Tumour, Nodes, Metastasis

33
Q

What staging system is used for Colorectal cancer?

A

Dukes

34
Q

What staging system is used for Hodgkins lymphoma?

A

Ann Arbor

35
Q

What happens in lymph node sampling?

A
  • Involved nodes found are cleared

- If no nodes found on examination/imaging, targeted sampling occurs

36
Q

What is a sentinel lymph node?

A

The first node or group of nodes that drain a cancer

37
Q

How can the sentinel node be found?

A

Contrast (dye and short half life isotope) injected into tumour site, then imaging to show where the contrast drains to

38
Q

What are sentinel lymph node biopsies used for routinely?

A
  • Breast cancer
  • Melanoma
  • Penile SCC
  • Head and neck SCC
39
Q

What does lymphoedema mean in breast cancer?

A

Associated with significant morbidity. Occurs after axillary clearance (traditional treatment in breast cancer)

40
Q

How does immunohistochemistry work in diagnosing cancer?

A
  • Antibodies bind to specific proteins in tissues

- Abs applied to tissue sections and detected via peroxidase reaction (fluorescent staining tag)

41
Q

How is PCR used in cancer diagnosis?

A
  • For assessment of clonality in lymphoid infiltrates - look for TCR or Ig heavy chain gene
  • Identifying HHV8 infection in Kaposi’s sarcoma
42
Q

What can In situ hybridisation be used for in cancer diagnosis?

A
  • Assess clonality in B cell lymphoid neoplasms
  • Detection of EBV via EBER (EB encoded RNA)
  • ID of tumour specific translocations
43
Q

How does HPV presence help predict the outcome of oropharyngeal cancers?

A

HPV-positive have a much better outcome compared to HPV-negative

44
Q

What can help determine therapy?

A

Presence of biological markers

45
Q

Give example of biological markers determining therapy

A
  • Steroid receptors and tamoxifen
  • Her-2 and Herceptin
  • C-kit expression and imatinib
  • CD20 expression and rituximab
46
Q

How frequently is HER-2 overexpressed in breast carcinoma?

A

20-30% of the time

47
Q

What is routine in breast tumours?

A

Screening for Her-2 expression

48
Q

What does herceptin treatment of Her-2 positive tumours lead to?

A

Improvement in survival