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Onco Board Review 2 > Exotics, RT, Misc. > Flashcards

Exotics, RT, Misc. Flashcards

1
Q

In 64 cats with digital carcinomas, what % represented metastasis from primary lung tumors?

A

87.5%

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2
Q

What % of dogs with digital SCC will have involvement of other digits?

A

3%

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3
Q

In dogs with digital SCC, __% have metastasis at presentation and __% go on to develop metastasis.

A
  1. 8%

23. 3%

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4
Q

What does trastuzumab target?

A

HER2/neu

therapeutic monoclonal antibody –> Herceptin

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5
Q

What do Th1 cells produce?

A

IL-2, IFN-gamma, TNF

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6
Q

What do Th2 cells produce?

A

IL-4, IL-5, IL-10

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7
Q

T/F: Thymomas are a common cause of mediastinal masses in rabbits and can be diagnosed with cytology.

A

True

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8
Q

What is the significance of the shoulder in radiation a survival curve?

A

The shoulder reflects an accumulation of sublethal damage to the cells (can be repaired and lead to an early rise in survival of cells)

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9
Q

What dose in Gy does alpha/beta ratio represent?

A

The dose in Gy when cell kill from the linear and quadratic components of the cell survival curve is equal.

Linear = # of hits due to one electron is proportional to dose
Quadratic = # of hits due to two separate electrons is proportional to square of dose
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10
Q

What is the appearance of cells with a high alpha/beta ratio vs. low when plotted?

A

high alpha/beta appears more linear, low has parabolic shape (i.e. greater shoulder)

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11
Q

What dose/fraction is best for low alpha/beta ratio cells?

A

high dose/fraction
(it has been suggested that tissues/cells with low alpha/beta ratios have a greater capacity for repair of sublethal radiation damage)

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12
Q

What tumors may have low alpha/beta ratios?

A

melanoma, prostatic tumors, STS, TCC, OSA

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13
Q

Which radiation effect is considered the most important for cell kill?

A 
Compton effect
(collision btw photon and electron - transfer of energy to the electron and the photon scatters in new direction; both can undergo further interactions until all energy is dissipated)
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14
Q

What is the Bragg peak?

A

Localized peak of dose that results from a particle beam.

Particle beam is radiation that uses beams of protons or other charged particles that have different depth-dose distributions compared to photons - they will deposit most of their energy in the last final mm of trajectory = Bragg peak. Treatment with heavy ions takes advantage of the Bragg peak.

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15
Q

What is RBE?

A

Relative biological effectiveness – ratio of the dose required to produce a specific biological effect with Co-60 photons (i.e. Co-60 is used as reference radiation) to the charged particle dose that is required to achieve the same biological effect

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16
Q

What are the four R’s of radiation?

A

Repair, Repopulation, Redistribution, Reoxygenation

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17
Q

Why is a port film such poor quality?

A

You’re using a therapeutic beam in megavoltage energy to obtain the image - there’re the interactions are occurring mainly by Compton scattering; shows less contrast compared to diagnostic x-rays

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18
Q

What is a negative of orthovoltage regarding acute side effects?

A

No skin sparing
(produces x-rays but lower voltage than linear accelerator so they don’t go as deep - higher energy goes deeper)

also bad for bone, increased dose to dense tissues

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19
Q

What kind of rays are produced by Cobalt 60? What is the energy? Is there skin sparing?

A

gamma rays
1.25 MV gamma – energy can’t be changed (comes from radioactive decay, can’t be made by linear accelerator)
Yes - skin sparing

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20
Q

At what energy range is photoelectric effect dominant? What about Compton?

A

Photoelectric - 10-30 keV (diagnostic range, pretty image)

Compton - 60 keV to 10 MeV (therapeutic range, bad image = port film)

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21
Q

What is the energy range of electrons? What is removed in the machine to produce electrons?

A

5-20 MeV

Remove Z target

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22
Q

What is LET? What has high LET? Low LET?

A

Linear energy transfer -rate of energy loss along a track of an ionizing particle
High LET = neutrons, low energy protons, alphas (i.e. big and bulky and hit everything)
Low LET = X-rays, electrons, gamma (not as biologically damaging per dose)

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23
Q

What is RBE? If a particle has higher LET, how does that affect RBE?

A

Relative biological effectiveness
Ratio comparing effectiveness of different types of ionizing radiations
Higher LET particles have higher RBE

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24
Q

What causes 2/3 of DNA damage? What causes the other 1/3?

A

Indirect action = 2/3 = OH radicals (occurs via H2O, requires oxygen to be present - ineffective in hypoxia)
Direct action = 1/2 = direct DNA damage (higher LET/RBE will cause more direct damage)

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25
Q

What type of death do most epithelial and mesenchymal tumors undergo after RT? What about lymphoma?

A 
epithelial/mesenchymal = mitotic death (die when they try to divide)
lymphoma = apoptotic death (aka interphase death), happens within hours
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26
Q

What is OER? How does higher LET and RBE affect OER?

A

oxygen enhancement ratio - enhancing therapeutic effects with presence of oxygen
Higher LET and RBE decrease OER because bigger, more damaging particles cats more direct DNA damage (and therefore oxygen not as necessary)

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27
Q

Which of the R’s are used to our advantage with fractionation?

A

Reoxygenation - well oxygenated cells die, others move closer to blood vessels
Redistribution - fractionation allows time for cells to redistribute to more sensitive phase of the cell cycle

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28
Q

What do you want dose-response relationship to look like with RT?

A

Evaluates tumor vs. normal - therapeutic ratio

Want tumor to left of normal (dose on x-axis), reality is there’s always overlap

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29
Q

What is the single biggest determinant of total radiation dose?

A

Late side effects

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30
Q

What is hyper fractionated dosing?

A

same total dose over same time

BID treatment - increased fractionations to achieve same dose as conventional

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31
Q

What is accelerated dosing?

A

same total dose but less overall time

severe acute side effects

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32
Q

What is the biggest determinant of late side effects?

A

dose per fraction (i.e. fraction size)

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33
Q

What is BED? What is the BED formula?

A

Biologically equivalent dose - used to see how “hot” different fractionation schemes are in comparison for a specified tissue

BED= nd [1+(d/aB)]

n=# of fractions
d=dose

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34
Q

When are cells most sensitive to hyperthermia (which makes it a good candidate to combine with RT)?

A

Kills in S phase (when most resistant to RT)

Kills hypoxic cells and in acidic environment where radio resistance exists

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35
Q

What drug is a radioprotector used in humans for dry mouth?

A

amifostine

36
Q

What drugs are used as hypoxic radiosensitizers?

A

nitroimadazoles (etanidazole, nimorazole) - toxicity issues

37
Q

What is radiation recall and what drug is this associated with?

A

recurrence of RT side effects when you start chemo

doxorubicin

38
Q

What causes delayed acute toxicity of CNS?

A

transient demyelination due to damaged/lost oligodendrocytes

39
Q

What dose is delivered with Sr90?

A

100-200 Gy, 1-2 fractions

40
Q

What effect of photon/electron in the MV energy range is eliminated with boluses?

A

skin sparing effect

41
Q

What is penumbra?

A

The rapid decrease at the edges of the radiation beam is called the penumbra region. Usually defined as the space between the 80% and 20% isodose lines.

42
Q

What clinical signs are seen in rabbits with thymomas? (Kunzel 2012)

A

dyspnea (76.9%), exercise intolerance (53.9%) and bilateral exophthalmos (46.2%)

43
Q

How effective was hypofractionated stereotactic RT for rabbit thymomas? (Dolera 2016)

A

Very! 15 rabbits, all had CR, none died of thymoma.

Tx with 40 Gy in 6 fractions

44
Q

What stains were positive in seminomas from rabbits? Behavior of seminomas? (Banco 2017)

A

Stains: placental ALP and periodic acid-Schiff (PAS)

Seminomas originate from monocytes - malignant, frequently metastasize

45
Q

What neoplastic process developed in cattle from exposure to bracken fern? (Faccin 2017)

A

annular esophageal SCC – consider this ddx for appearance of esophageal scar tissue in cattle

46
Q

What is a diagnostic marker for devil facial tumor disease? What is the origin of the disease?

A

periaxin is diagnostic marker

peripheral nerve sheath neoplasm of Schwann cell origin

47
Q

Where is bovine LSA found?

A

HAULS

heart, abomasum, uterus, LN, spine

48
Q

Most common hemostatic alteration in dogs with cancer?

A

hypercoagulability

49
Q

How many dsDNA breaks are created in each cell after 1 Gy of RT?

A

40

50
Q

What is gradient index in RT?

A

evaluates dose falloff - dose outside target volume

51
Q

What is dose conformity index in RT?

A

evaluates degree to which the dose distribution conforms to the size/shape of the target volume
CI = 1 is perfect (no radiation outside PTV), >2 usually acceptable, <1 means less than 100% of PTV covered by Rx

52
Q

What % of dogs with hyperCa have neoplasia?

A

66%

33% of cats

53
Q

Which of the following is not a cause of hyperCa in dogs?

  1. PTHrp
  2. IL-1B
  3. TNF-a
  4. PGE1 and 2
  5. RANKL
A

TNF-a

54
Q

What is the MOA of Lasix treating hyperCa?

A

inhibits Ca resorption in the ascending loop of Henle

55
Q

What is the MOA of pred in treating hyperCa?

A

inhibits PGE, IL-1B, Vit D, and intestinal calcium absorption
(also cytotoxic for LSA and MM)

56
Q

What is the most common non-islet cell tumor to cause hypoglycemia?

A

HCC

57
Q

What lab work abnormality is seen with SIADH?

A

hyponatremia

58
Q

Which chemo agents can cause SIADH?

A

vincristine, CTX, cisplatin

59
Q

Which tumor type has been linked to ectopic ACTH syndrome in dogs?

  1. oral SCC
  2. leiomyosarcoma
  3. pancreatic tumors
  4. primary lung tumors
  5. thyroid tumors
A

primary lung tumors

60
Q

Name 3 tumor types that can result in hypergammaglobulinemia

A

MM
LSA
CLL

61
Q

What two repro tumors can cause anemia?

A

Sertoli cell in males, granulosa cell in females

due to hyperestrogenism

62
Q

Which tumor type has not been reported to cause erythrocytosis:

  1. oral melanoma
  2. TVT
  3. cecal leiomyosarcoma
  4. nasal FSA
  5. renal LSA
A

oral melanoma

63
Q

Cutaneous flushing can be associated with what two tumor types?

A

pheochromocytoma

MCT

64
Q

What PNS can be seen with glucagonoma?

A

necrolytic migratory erythema/superificial necrolytic dermatitis
GI ulceration

65
Q

Which PNS has not been reported with thymoma?

  1. exfoliative dermatitis
  2. myasthenia gravis
  3. polycythemia
  4. erythema multiforme
  5. polymyositis
A

polymyositis

66
Q

Which condition has not been associated with HO?

  1. perianal adenocarcinoma
  2. primary lung tumors
  3. pulmonary metastatic disease
  4. pregnancy
  5. HW disease
A

perianal adenocarcinoma

67
Q

What are the major cytokines involved in paraneoplastic fever?

A

IL-1, IL-6, TNF-a, interferons, febrile-promoting prostaglandins

68
Q

What is gadoxetate disodium? What were results using this agent in dogs with HCC? (Constant 2016 - Cannon on paper)

A

liver-specific contrast agent

hepatic lesions were found in 3/7 patients that were not seen on previous imaging

69
Q

What are effects of CK2 in cancer? (Cannon research)

A

It is a serine/threonine kinase that causes:
suppression of apoptosis
activate oncogenic pathways like NFkB, Wnt/B-catenin, PI3K/Akt
inactivates tumor suppressors

They tested RNAi targeting CK2 in FOSCC - tolerated and there was some efficacy

70
Q

What is the TRAP assay? What were results with TCC? (McCleary-Wheeler 2010)

A

telomeric repeat amplification protocol

telomerase activity was detected in TCC urine, could be diagnostic test

71
Q

Is immunity from previous vaccinations compromised by chemotherapy? (Henry 2001, Higginbotham on paper)

A

No

72
Q

What was ORR in horses treated with chemo for LSA? MST? (Luethy 2018)

A

ORR 93.3% (33.3% CR, 60% PR)
MST 8 months
2/3 experienced AE

73
Q

What do red and green mean on gene microarray?

A 
red = genes whose expression in tumors is higher than reference sample
green = genes whose expression in tumors is lower than reference sample
black = no change
74
Q

In which canine population can X-chromosome inactivation pattern analysis be useful to assess cell clonality?

A

female dogs that are heterozygous for the androgen receptor gene (Mochizuki VP 2015)

75
Q

In a recent study on the effects of toceranib in dogs with various neoplasia, which significant changes were seen in systolic blood pressure and/or proteinuria compared to control dogs? (Tjostheim JVIM 2016)

A

systolic blood pressure was significantly higher in previously normotensive treated dogs after initiation of toceranib as compared to baseline.

(proteinuria and BP at baseline were not different from age-matched controls for the dogs with cancer)

76
Q

What are some unusual cancers that have been reported with HO? (Withers 2015)

A

tumours of the bladder (undifferentiated sarcoma, botryoid rhabdomyosarcoma) or kidney [transitional cell carcinoma (TCC)
Other random things: infectious/inflam lung disease, heart worm, Spirocerca lupi esophageal granuloma, bacterial endocarditis, R to L shunting with PDA, congenital megaesophagus

77
Q

Clin path observations with HO (expanded)? (Withers 2015)

A

haematological and serum biochemical alterations such as anaemia, neutrophillic leukocytosis with or without a left shift, thrombocytosis, thrombocytopaenia, elevated ALKP, hypoalbuminaemia and hyperglobulinaemia are frequently observed

78
Q

What PE abnormality is frequently seen in dogs with HO and is sometimes the presenting complaint? (Withers 2015)

A

ocular abnormalities

79
Q

How was the anemia most commonly characterized with HO? (Withers 2015)

A

microcytic

80
Q

Sensitive marker of oxidative DNA damage?

A

8-oxo-deoxyguanosine

81
Q

What does Comet assay detect?

A

detects DNA damage at cellular level

82
Q

What does Ames assay detect?

A

uses bacteria to test whether a given chemical can cause DNA mutation

83
Q

In which DNA repair pathway is the enzyme poly (ADP-ribose) polymerase involved?

A

Base excision repair

84
Q

Which chemo agents are most likely to cause febrile neutropenia in cats?

A

lomustine and vinca alkaloids

Pierro febrile neutropenia cats VCO 2017

85
Q

When in the cell cycle are taxanes effective?

A

metaphase/anaphase junction

86
Q

What is the DLT of docetaxel?

A

GI upset

Onco Board Review 2 (20 decks)

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