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LEAH FCP > Introduction to neoplasia > Flashcards

Introduction to neoplasia Flashcards

1
Q

Define neoplasia

A

Process of abnormal cell proliferation

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2
Q

Define neoplasm

A

Abnormal mass of tissue due to abnormal cell proliferation

(AKA tumour)

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3
Q

What are the 3 types of neoplasm/tumours

A
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4
Q

Define oncogenesis

A

Process of gradual steps towards tumour development

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5
Q

What is the difference between pre-malignant and malignant tumours?

A

in pre-malignant tumour basement membrane is still intact & tumour has not spread to other tissues

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6
Q

How do we determine if a mass is neoplasia?

A

Take a sample for histology

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7
Q

What should we examine in a histological sample to look for neoplasia

A

Organisation of tissue structure
Degree of cellularity
Nuclear to cytoplasmic ratio
Nuclear morphology
Necrosis
Mitotic index
Individualisation of cells
Invasiveness of cells

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8
Q

How do you differentiate between a benign vs malignant tumour?

A
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9
Q

What are some characteristics of benign tumours

A

Slow-growing mass

Good demarcation from surrounding tissue (capsule)

Does not spread (no metastasis)

Minimal necrosis

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10
Q

What are some characteristics of malignant tumours

A

Can grow rapidly

Invasiveness to surrounding tissue

Can spread to other sites in body (metastasis)

Increased necrosis

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11
Q

Fill in the table of features of benign vs malignant tumours

A
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12
Q

Why does necrosis often occur in malignant tumours?

A

Tumours grow too rapidly for blood supply to support centre of the mass => death of cells

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13
Q

Why do tumours often get infected?

A

Loss of blood supply to centre => no WBCs

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14
Q

What is the cytological criteria of malignancy

A
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15
Q

Fill in the table with features of benign vs malignant tumour cells

A
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16
Q

Which genes control cell division/proliferation?

A

Proto-oncogenes - promote proliferation

Tumour suppressor genes - suppress proliferation or induce cell death

(dysregulation of these mechanisms = neoplasia)

17
Q

How does cell proliferation become dysregulated?

A
  1. Proto-oncogenes mutate into oncogenes
  2. Oncogenes code for oncoproteins that promote cell division despite:
    - absence of promotion signals
    - presence of normal check point controls to suppress division

Tumour suppressor genes can become mutated so they no longer suppress cell division => neoplasia

18
Q

What factors contribute to oncogenesis?

A

Genetic factors
Epigenetic factors
Environmental factors

19
Q

Why does cancer occur more commonly in older patients?

A

Multiple hit hypothesis - 1 mutation not enough to cause neoplasia on its own - takes time for mutations to develop & accumulate

20
Q

What are the hallmarks of cancer cells?

A
21
Q

What is mutagenesis/carcinogenesis?

A

Initiating factor(s) causing genetic change

This genetic change makes cells more likely to divide in uncontrolled way in right conditions

Caused by intrinsic and extrinsic factors

22
Q

define mutagen & carcinogen

A

Mutagen = agent that damages DNA

Carcinogen = mutagen that causes neoplasia

All carcinogens are mutagens, but not all mutagens are carcinogens

23
Q

What are the intrinsic factors of mutagenesis?

A

Normal by-products of cell metabolism that cause DNA damage

e.g. reactive oxygen species (ROS) a.k.a free radicals

24
Q

What are the extrinsic factors of mutagenesis?

A

Environmental agents
- Chemical
- Physical

Oncogenic viruses

25
Q

Describe direct- vs indirect-acting chemical agents that act as extrinsic factors of mutagenesis

A

Direct-acting
- Cause mutagenesis in form in which they enter body
- e.g. nitrosamines in tobacco smoke

Indirect-acting
- Need to be activated by enzymes in body to cause mutagenesis
- Most important enzyme is cytochrome P450 in the liver
- Also called procarcinogens
- e.g. ptaquiloside in bracken fern => bladder tumours in cattle

26
Q

Describe physical agents that act as extrinsic factors of mutagenesis

A

Cause direct DNA damage & ROS generation
- ROS can cause G to T transversion

Key physical agent is radiation
- All types of radiation are complete carcinogens
- Initiators of oncogenesis
- Also promoters of oncogenesis through continued exposure

27
Q

Describe ultraviolet radiation (sunlight) as an (physical agent) extrinsic factor of mutagenesis

A

Ultraviolet radiation (sunlight) causes:
- Pyrimidine (C &T) dimer formation (results in misreading during transcription)
- ROS generation

28
Q

describe the direct mechanisms of oncogenic viruses

A

Dominant oncogene mechanism:
- Mutation in viral gene causes host cells to produce oncoprotein
- e.g. Feline leukaemia virus

Insertional mechanism:
- No oncogene in virus
- Insertion of viral DNA into host cells activates proto-oncogenes => oncogenes
- e.g. Avian leukosis virus

29
Q

describe the indirect mechanisms of oncogenic viruses

A

Suppress host immune system
- e.g. Gallid herpesvirus-2 (Marek’s disease)

Directly stimulate host cell proliferation
- e.g. Leporipoxvirus (Squirrel fibroma virus)

30
Q

Define metastasis

A

Movement of cancer cells from one tissue/organ to another

(key feature of malignancy)

31
Q

Describe the process of metastasis

A

Process can take years, but can also be rapid

  1. Cancer cells break away from primary tumour
  2. Cells travel through blood & lymphatic vesselsto new tissues/organs distant from primary tumour
  3. Secondary tumours (metastases) develop in new organs

Metastases –new cancerous growths at distant sites

32
Q

Give an example of a highly metastatic and poorly metastatic tumour

A

Some tumours highly metastatic e.g. melanoma

Some are poorly metastatic e.g. squamous cell carcinoma

33
Q

Why is it important to identify tumours when they’re small?

A

Generally- the bigger the tumour, the more likely it is to metastasise

34
Q

What are the pathways of metastasis

A

Haematogenous
- Cancer cells travel in blood vessels
- Usually thinner-walled veins rather than arteries

Lymphatic
- Cancer cells travel in lymphatic vessels
- Lymph node(s) closest to tumour are colonised first
- These first lymph nodes develop largest tumours

Transcoelomic- less common
- Cancer cells spread across surface of abdominal & thoracic structures

35
Q

What are the fundamental steps for metastasis

A

Intravasation
Extravasation
Colonisation

LEAH FCP (77 decks)

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