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PVS > Oncology 3 > Flashcards

Oncology 3 Flashcards

1
Q

Define cure

A

Tumour gone, no further therapy needed

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2
Q

Define complete remission

A

No evidence of tumour on physical exam, haematology, biochemistry, or imaging (but may still have micrometastases)

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3
Q

Define partial remission

A

Reduction in sum of longest diameters of >30% with no new lesions at 4 weeks

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4
Q

Define Stable disease

A

No change at 4 weeks

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5
Q

Define Progressive disease

A

Increase of 20% or more in longest diameter at 4 weeks, or new lesions

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6
Q

Define induction chemotherapy

A

Intensive period of treatment to try and reduce number of cancer cells

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7
Q

Define maintenance chemotherapy

A

Lower dose, less intensive treatment to maintain remission

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8
Q

Define rescue chemotherapy

A

Re-introduction with non first-line agents when one protocol has failed, as aggressive as induction therapy

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9
Q

Define median survival time in chemotherapy

A

Half of patients relapse or died and half still in remission following a protocol

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10
Q

Define disease free interval in chemotherapy

A

Time to progression after onset of therapy e.g. metastases after osteosarcoma amputation

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11
Q

Define adjuvant chemotherapy

A

Adminsitered after surgery or radiotherapy, usually limit metastases forming

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12
Q

Define neoadjuvant chemotherapy

A

Used to shrink mass before surgery or radiotherapy

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13
Q

Define nadir

A

The point at which the lowest white blood cell count occurs

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14
Q

Define maximum tolerated dose in chemotherapy

A

Maximum recommended dose of an agent, either at one time or cumulatively

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15
Q

What can radiotherapy be used for?

A
  • Curative treatment

- Palliative treatment

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16
Q

Outline the use of radiotherapy as a curative treatment

A
  • Can be sole treatment (rare) e.g. isolated lymphoma

- Or adjunctive treatment (usual) e.g. mast cell tumours, sarcomas

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17
Q

Outline the use of radiotherapy as a palliative treatment

A
  • Relieve pain
  • Reduce physical obstruction
  • Relief of clinical symptoms
  • Treatment of neurological signs
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18
Q

What are the mechanisms by which radiotherapy works in the treatment of cancer?

A
  • Kills cells by direct effect on DNA
  • Indirect effects of free radicals
  • Oxygen effect
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19
Q

What tissues are acutely responsive to radiotherapy and what are the characteristics of acute response?

A
  • Tissues with rapid cell proliferation

- Effects develop immediately and are self limiting

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20
Q

How does DNA damage by radiation lead to cell killing?

A

DNA damage leads to cell death during cell division

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21
Q

Outline free radicals in radiation cell killing

A
  • Ionisation of water (interstitial fluid around cells) leads to free radicals
  • OH radical very reactive and accounts for most of the radiation damage
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22
Q

Outline the oxygen effect in radiation therapy

A
  • high O2 fixes free radical damage to DNA
  • Cells separated from capillary bed >100um are hypoxic, which protects cells from radiation damage, hence large tumours are less sensitive and small tumours (with less cells to kill) are more sensitive to radiation damage
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23
Q

Outline what is meant by cycling death in radiotherapy

A
  • Limited to dividing cells
  • Achieved at lower doses (are more sensitive)
  • Growth fraction and doubling time of cells important
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24
Q

Outline what is meant by interphase death in radiotherapy

A
  • Targets cells that are not in mitosis
  • Resistant cells ultimately susceptible
  • High doses generally required
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25
Q

What are the characteristics of later responding tissues to radiotherapy?

A
  • Slow rate of cell proliferation

- Effects develop months to years after therapy, irreversible

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26
Q

What is the unit of radiation?

A

Gray (Gy)

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27
Q

Describe radiation dosage

A
  • Usually centiGy (cGy)
  • Total dose fractioned over multiple treatments, one treatment = a fraction
  • e.g. 57cGY total dose over 19 fractions = 3cGY per dose
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28
Q

What are the classifications of radiation therapy?

A
  • Teletherapy (external beam radiation)
  • Brachytherapy (interstitial beam radiation)
  • Systemic radiation
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29
Q

How is teletherapy delivered?

A

x-ray or gamma-ray beams

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30
Q

How is brachytherapy delivered?

A

Implants

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31
Q

How is systemic radiation delivered?

A

Injected

32
Q

What are the 2 types of voltage used in teletherapy?

A

Orthovoltage (low medium energy range) and megavoltage (6-10x that of ortho)

33
Q

Outline the features of teletherapy

A
  • Most common method
  • Does not result in radioactive patient
  • Directed into the tumour
  • Mega or orthovoltage used
34
Q

What are the advantages of orthovoltage teletherapy?

A
  • Simple
  • Low cost
  • Less shielding requirements
35
Q

What are the disadvantages of orthovoltage teletherapy?

A
  • Penetration low
  • Maximum dose applied to skin
  • Increased absorption of dose in bone relative to soft tissue
36
Q

How is megavoltage teletherapy administered?

A

Using a linear accelerator (x-rays) or cobalt unit (gamma rays)

37
Q

What are the advantages of megavoltage teletherapy?

A
  • Skin sparing as max dose is >0.5cm below surface
  • Less scatter so less radiation sickness
  • Uniform dose to bone and soft tissue
38
Q

What are the disadvantages of megavoltage teletherapy?

A
  • High cost
  • High shielding requirements
  • Expertise required
39
Q

Outline the use of clinical radiation generators

A
  • Less common as produce radioactive patient
  • Good for skin tumours
  • Includes brachytherapy and systemic therapy
40
Q

What is brachytherapy?

A

Use of a clinical radiation generator i.e. is radioactive substances which emit gamma/beta rays applied to/near tumour

41
Q

When is brachytherapy commonly used?

A
  • Large animals e.g. horse

- Good for skin tumours, often facial

42
Q

What are the disadvantages of brachytherapy?

A
  • Radioactive patient during therapy
  • High cost
  • Ugly appearance for ~6 months
  • Tumours take weeks-months to shrink
43
Q

What is meant by sublethal damage and how does it relate to radiation therapy?

A
  • Cell is damaged but not killed by a radiation event

- The next dose should be delivered before the damage and be repaired

44
Q

What are the advantages of radiation dose fractionation?

A
  • Repair of normal cells (while cancer cells have limited ability to repair DNA)
  • Re-oxygenation of cancer cells (need to be oxygenated to die with radiation therapy)
  • Re-distribution of cancer cells in cell cycle
45
Q

In what phases of the cell cycle are cancer cells most susceptible to cell death by radiation?

A

G2 and M phase

46
Q

What are the 2 fractionation protocols commonly used?

A

Hypofractionated protocols and fine fractionation protocols

47
Q

Outline hypofractionated radiation protocols

A
  • Few large doses of radiation weekly for ~4 weeks

- Usually 800-900cGY/fraction

48
Q

What is the main limitation of hypofractionated radiation protocols?

A

Severe limitations on total dose because of normal tissue tolerances

49
Q

Outline fine fractionation radiation protocols

A
  • Greater number of doses given over ~4 weeks

- Usually 200-300cGY/fraction

50
Q

What is the main advantage of fine fractionation radiation protocols?

A

Can achieve higher total dose and so better long term survival for many cancer patients

51
Q

What tumours or highly sensitive to radiation therapy?

A
  • Lymphoma
  • Seminoma
  • Transmissible venereal tumours
  • Perianal adenoma/adenocarcinoma
  • Solitary plasmacytoma
  • Neuroblastoma
52
Q

What tumours are sensitive to radiation therapy?

A
  • Nasal adenocarcinoma
  • Mast cell tumours
  • Squamous cell carcinomas (skin)
  • Metastatic lymph nodes (<1cm)
  • Gliomas
  • Basal cell carcinomas
  • Pituitary tumours
53
Q

What tumours are moderately sensitive to radiation therapy?

A
  • Soft tissue sarcomas
  • Bladder transitional cell carcinoma
  • Protastatic carcinoma
  • Metastatic lymph nodes (>3cm)
  • Oral melanoma
  • Meningioma
  • Thyroid carcinoma
54
Q

What tumours are resistant to radiation therapy?

A
  • Bone sarcomas (but can be palliative)
  • Metastatic lymph nodes (>6cm)
  • Head and neck tumours (>4cm(
55
Q

Outline what is meant by multimodality treatment of cancer

A
  • Use of multiple treatments

- e.g. combination of radiation and/or chemotherapy

56
Q

When is radiation combined with surgery?

A
  • When surgery alone is not sufficient to eradicate residual subclinical disease
  • Pre-operatively when post-op is not feasible (position of incision) or for those that are not resectable
57
Q

What is the key side effect of external beam radiotherapy (teletherapy)?

A

Most side effects occur at skin level as this is where the maximum dose ends up

58
Q

What is radiation toxicity and where does it occur?

A
  • Complication arising from radiation, either acutely or chronic
  • Radiation is not selective to tumour cells and so can occur in any cell/tissue
59
Q

What are the consequences of acute radiation toxicity?

A
  • Manage symptomatically ad usually does not result in the cessation of treatment
  • Manifestation depends on tissue
60
Q

Give the manifestation of acute radiation toxicity in the following tissues

  • Skin
  • Oral cavity
  • Nasal cavity
  • Ocular
  • Foot
  • Lung
A
  • Skin: moist desquamation, alopecia
  • Oral: mucositis, salivation, halitosis
  • Nasal: discharge
  • Ocular: corneal ulcer
  • Foot: pad slough, nail loss
  • Lung: pneumonitis
61
Q

Give the manifestation of chronic radiation toxicity in the following tissues:

  • Skin
  • Oral cavity
  • Nasal cavity
  • Ocular
  • Extremity
  • Gastrointestinal
  • Brain
  • Spinal cord
  • Kidney
  • Lung
A
  • Skin: fibrosis, leukotrichia, non-healing ulcer
  • Oral: bone necrosis, periodontal disease
  • Ocular: KCS, cataract, retinal damage
  • Extremity: neuropathy, fibrosis, contracture
  • GI: stricture, ulcer
  • brain: encephalopathy, infarct
  • Spinal cord: myelopathy, infarct
  • Kidney: fibrosis
  • Lung: pneumonitis
62
Q

Outline chronic radiation toxicity

A

May have onset months to years after treatment (but can also start acutely), and may result in the formation of a second neoplasm

63
Q

What sites should be avoided with radiotherapy?

A
  • Eyes
  • Nasal planum
  • Foot pads
  • Circumferential extremity
  • Major internal organs
64
Q

What diagnostic techniques should be included in a mast cell tumour work up?

A
  • FNA (diagnoses 92-96% of MCTs)
  • Histopathology for grading
  • Assessment and aspiration of local lymph nodes
  • Ultrasound imaging of liver and spleen
  • Rarely metastasise to thorax so radiograph not as important
65
Q

What grading systems can be used to grade a mast cell tumour on histology?

A
  • Patnaik system
  • Kiupel system (newer)
  • Proliferation markers
66
Q

What proliferation markers are assessed with mast cell tumours?

A
  • Mitotic index
  • AgNOR (archyrophilic nucleolar organiser region)
  • Ki67
  • PCNA (proliferating cell nuclear antigen)
67
Q

What is the significance of a high Ki67 on mast cell tumour histology?

A

Worse prognosis (indicates higher proliferation)

68
Q

What grades are used in the Patnaik system?

A
  • Well differentiated (rarely metastasis, low grade)
  • Intermediate (uncommonly metastasise)
  • Poorly differentiated (>75% metastasise)
69
Q

What does a stage 1 lymphoma mean?

A

Single node or lymphoid tissue in a single organ affected

70
Q

What does a stage 2 lymphoma mean?

A

Regional nodal involvement +/- tonsils

71
Q

What does a stage 3 lymphoma mean?

A

Generalised lymphadenopathy

72
Q

What does a stage 4 lymphoma mean?

A

Hepatic and/or splenic involvement

73
Q

What does a stage 5 lymphoma mean?

A

Manifestation in blood, bone marrow and other organs

74
Q

In clinical staging, what do subsets “a” and “b” mean?

A 
a = animal is well 
b = animal is sick
75
Q

What are some common complications with lymphoma?

A
  • Hypercalcaemia
  • Anaemia
  • Thrombocytopaenia
  • White blood cell abnormalities
  • Hypergammaglobulinaemia
76
Q

What are common sites on the appendicular skeleton for osteosarcomas?

A
  • Forelimb more than hind

- Distal radius, proximal humerus

77
Q

What are common sites on the axial skeleton for osteosarcoma?

A
  • Mandible
  • Maxilla
  • Spine
  • Ribs

PVS (23 decks)

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