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Radiation Therapy 2 > Skin > Flashcards

Skin Flashcards

1
Q

What are the 2 types of skin cancer?

A

Melanoma

Non Melanoma Skin Cancer NMSC

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2
Q

What are the two types of NMSC?

A

Basal Cell carcinomas

Squamous cell carcinomas

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3
Q

Where do melanomas commonly metastasise to?

A

brain
lung
small bowel
liver

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4
Q

What are some characteristics of melanomas?

A

very aggressive
unpredictable pattern of spread
blood & lymphatic spread early
Highly Radioresistant

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5
Q

What are the general ways for treating melanomas?

A

surgery and chemo
immunotherapy
megavoltage for metastases

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6
Q

What are the common melanoma dose fractionations for adjuvant RT after LN dissection?

A

50Gy/ 20#, 60Gy/ 30#

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7
Q

What are the common melanoma dose fractionations for palliative RT?

A

8Gy single fraction
20Gy/ 5#
36Gy/6# once weekly

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8
Q

What are the common melanoma dose fractionations for metastasis whole brain RT?

A

12Gy/ 2 daily fractions given on consecutive days

20Gy/ 5#

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9
Q

For NMSC what is the ratio of BCCs to SCCs?

A

3:1

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10
Q

What are the treatment options for BCC & SCC?

A

Surgery (cryosurgery, electrodessication & curettage, Moh’s micrographic surgery, wide local excision, skin grafting, LN dissection)
Topical chemotherapy
Photodynamic therapy
RT

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11
Q

What is Cryosurgery?

A

Liquid Nitrogen spray
Used for small superficial lesions (tissue dies, scab forms and drops off)
Cost-effective but not suitable near organs such as eyes

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12
Q

What is Electrodessication and Curettage (ED&C)?

A 
Electrodessication burns tumour
tumour is then scraped away
Electric need to cauterise & kill margin
Good cosmetic outcome
Used on small lesions, multiple lesions
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13
Q

What is Moh;s Micrographic Surgery?

A

Microscopic examination of tumour slices so normal tissue is spared
Tracks and removes cancer and its roots
Good for the nose, eyelids, lips, hairline, hands, feet & genitals

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14
Q

What is a Wide Local Excision?

A

For incomplete excision or inadequate margins
may require a skin graft
local or general anaesthetic

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15
Q

What is Topical Chemotherapy?

A

5FU (fluorouracil) or Imiquimod creams
home application
steroid creams added if necessary (for swelling)

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16
Q

What is Photodynamic Therapy (PDT)?

A

hypersensitise cells to light then inject or topical application of drug (5-ALA)
Laser then kills cells
keep covered and dry for 36hours, scab forms and falls off in 3 weeks

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17
Q

What are the advantages of surgery?

A

can have good cosmetic result,
quick and safe
Good for lesions that recur after RT
Usually SCC needs wider excision due to possible lymphatic spread
Treatment of choice for nodal involvement

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18
Q

What are the disadvantage of surgery?

A

general anaesthetic for large tumours
skin grafting may be necessary
risk of post-op complications
difficult sites (inner canthus of eye)

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19
Q

What are some indications for using radiation therapy?

A

-patients who are medically unfit for surgery or anaesthetic
-Cosmesis (face)
preserve function (lower eyelid, lip, nose, inner canthus)
-patients prone to keloid
-recurrence
-positive margins
-perineural or lymphovascular spread invasion
-Large superficial tumours where: surgery would cause major loss of function (e.g. mouth dribbling, numbness) or mutilation would be involve (e.g. ear amputation, nasectomy)

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20
Q

In what circumstances would you not use RT?

A

young people (scar less noticeable than shape of RT field + telangiectasisa, risk of 2nd malignancy, fibrosis)
previous RT
area prone to trauma
upper eyelid

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21
Q

What is superficial treatment?

A

superficial (kV photons)
Electron
HDR Brachytherapy

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22
Q

What are superficial kV photons used for?

A

small tumours
frail patients
lesions <3cm diameter and <5mm thick

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23
Q

What are common fractionations for SXRT (superficial x-ray RT)?

A

36Gy/ 8# in 17 days (M/W/F)
30-32Gy/ 4# (one or two fractions/ week)
18Gy single fraction

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24
Q

What are the immoblisation restrictions for skin treatments?

A

any position as long as it’s reproducible and stable
supine, prone, decubitus, semi prone, seated
headrests, pillows, sandbages
Bolus/ rice bags
Head and neck cast for lesion on head

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25
Q

What is a clinical mark up?

A

must record enough info to reproduce set up
ususally not tattooed (especially if on face)
tracings required
photos

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26
Q

What shielding is used?

A

thickness depends on energy used (e..g. 4mm for electrons up to 10MeV)
individual cutouts for small lesions
LMPA cut out insert
secondary x-rays absorbed in lead
wax may be aded to provide build up to dose at skin
may need extra protection for eyes/ nasal cavity

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27
Q

When would direct field or fixed angles be used for electron treatment?

A

used if we want to avoid critical structures of match to another field

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28
Q

What is skin apposition?

A

best contact

want skin perpendicular to electron applicator

29
Q

What are the advantages of electrons?

A

varying energy
can reach certain depth doses (depending on energy)
rapid fall off at depth
can treat lesions near bone and cartilage

30
Q

What are the disadvantages of electrons?

A

difficult to match fields due to bowing isodose curves (treatment area is greater than that seen on skin surface)
Not possible to treat field sizes <4cm

31
Q

What is the common dose fractionations for SCCs <5cm diameter?

A

45Gy /9# on alternate days over 3 weeks

54Gy/20# daily

32
Q

What is the common dose fractionations for SCCs >5cm diameter?

A

50-54Gy/20#

66Gy/ 33#

33
Q

What is the common dose fractionations for Post-Op XRT?

A

50Gy/ 20#

60Gy/ 30#

34
Q

What are common acute side effects?

A

erythema
dry itchy skin
dry/moist desquamation

35
Q

What are common chronic side effects?

A

pigmentation
telangiectasia
ischaemia
thickening

36
Q

What are keloid scars?

A

follow surgical excision
RT indicated within 24-72 hours
6-9Gy/ 1#

37
Q

What are the characteristics of BCC?

A

slow growing

rarely metastasize

38
Q

What are the basal cell subtypes?

A 
nodular/redent ulcer
superficial subtype
morpheic (sclerosing)
infiltrative similar looking to morpheic
pigmented = bluey/black looks similar to melanoma
39
Q

What are the characteristics of SCC?

A

potential to metastasise

can be aggressive and grow quickly

40
Q

What are the Squamous subtypes?

A

Bowen’s disease pre-invasive SCC in situ
verrucous
spindle cell variant

41
Q

What are the different routes of spread for SCCs?

A 
perineural spread (2.5-5%) (cancer spreading to space around nerve) 
lymph node
dermal lymphatics
local invasion
pericartilageous spread
distant metastases
42
Q

What are the corresponding sizes for TNM staging for primary BCC?

A 
T1 = ≤2cm
T2 = >2cm but ≤5cm
T3 = >5cm
T4 = Deeply invades beyond s/c tissue
43
Q

How do 5 year control rates reflect BCC size?

A

as the size increases the 5 year control rate decreases

44
Q

How does RT with surgery benefit patients?

A

higher 5 year control rates for BCC & SCC

45
Q

What are the causes of BCC, SCC or melanomas?

A

-UVA, UVB (sun exposure)
-immunosuppressants (organ transplant
-arsenic exposure
-genetic disorders (Gorlin’s syndrome, albinism)
Marjolin’s uler type scar cancer

46
Q

Why might adjuvant RT be given more for SCC than BCC?

A

probability of locoregional recurrence is greater initially for SCC. With the addition of RT the probability can be reduced significantly

47
Q

What target volume margin should BCC’s have?

A

No less than 5mm

48
Q

What target volume margin should SCC’s have?

A

10mm

49
Q

How do you select which filter to use for superficial

A

Higher HVL mm Al, the larger the lesion

50
Q

For superficial RT what is the minimum % depth dose to the specified tumour depth?

A

80%

51
Q

For superficial RT what varies the depth dose?

A

Filter
Field size
SSD

52
Q

What are common dose fractionations for Superficial RT treatment?

A

18Gy/ 1# (can have bad side effects)
21Gy/ 3# (1#/ week)
24Gy/ (4# (1-2#/week)
36Gy/ 10-12 (4-5#/ week)

53
Q

What is the second most common head and neck cancer after skin?

A

Lip
(1/4 of oral cavity tumours
90% affect lower lip
secondary to sun exposure and pipe smoking)

54
Q

What do we look for in a lower lip cancer?

A

Non-healing ulcer
Direct extension (through skin to muscle)
Perineural involvement (involve mental nerve
Infrequently spread to LN

55
Q

Where can the lip lymphatics spread to?

A

Upper: (Submandibular, Pre-auricular or Upper cervical jugulodigastric LN)
Midline lower: submental LN
Lower lateral : ipsilateral submandibular LN

56
Q

How are lip cancer typically managed?

A

Surgery (very small lesion – primary closure if <30% involvement)
Larger lesions require transposition flap

57
Q

Why would EBRT be used for lip lesions?

A

≥3cm (cosmetic benefit)
elderly
recurrence post-surgery
nodal involvement

58
Q

What is a typical dose fractionation for electron beam to lip?

A

55-66Gy @100% in 20# over 4 weeks OR equivalent to 49.5-54Gy @90% in 20# over 4 weeks
wax build up with first 90% at the skin surface

59
Q

When would photons be used?

A

If lymph node involvement

OR areas where difficult contour

60
Q

When would brachytherapy be used?

A

Early T1 and small T2

61
Q

What are the melanoma subtypes?

A

superficial spreading (most common)
Lentigo Maligna (most common in elderly on hands and face
Acral lentiginous melanomas (most common in darker skinned people)
Mucosal lentiginous melanoma
Nodular Melanoma

62
Q

How does TNM staging differ for melanoma?

A

T level describes thickness (depth) of lesion

thicker the more aggressive

63
Q

What are indications for RT for melanomas?

A

unresectable or residual lentigo maligna or lentigo maligna melanoma
desmoplastic/ neurotropic melanoma of the head and neck
in-transit disease (multiple nodules)
recurrences after surgery
nodal disease (high risk patients)
symptomatic metastasis

64
Q

What are typical dose fractionations for primary and in-transit melanoma?

A

50Gy/ 20# for unresected disease

48Gy/ 20# for resected disease (most common)

65
Q

What are the typical dose fractionation for resected nodal disease for melanoma?

A

30Gy/ 5# (twice weekly)
33Gy/ 6# (twice weekly)
48Gy/ 20# daily

66
Q

What is merkel cell cancer?

A

Merkel cell carcinoma is a rare type of skin cancer that usually appears as a flesh-colored or bluish-red nodule, often on your face, head or neck.
Malignancy of primary neural cell found within the basal layer of the epidermis or grouped together to form the tactile hair disc of Pinkus and function as a type 1 mechanoreceptor
-high rate nodal involvement

67
Q

What are the characteristic of MCC?

A

relatively uncommon
>65 years old
predominance in males and caucasians
occurs most commonly in sun-exposed areas (50% head and neck, 40% extremities)

68
Q

How do you treat MCC?

A

surgery & RT

If RT is to be used as adjuvant, the adequacy of the surgical margin becomes less critical

69
Q

When should RT commence after surgery for MCC?

A

rapid repopulation after surgery, RT should be commenced as soon as the wounds have healed
tumour is radiosensitive

Radiation Therapy 2 (5 decks)

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