Quiz 3 Flashcards
3 main types of skin cancer
Basal cell
Squamous cell/cutaneous squamous cell
Malignant melanoma
Slower form of skin cancer, not very aggressive and doesn’t tend to metastasize
Most prevalent cancer in humans
If untreated, can create damage
Can appear anywhere on body; common on head, neck, and other sun-exposed areas
Younger with sunburns at greater risk
1-2 million cases yearly, RT when cosmesis is ideal (face)
Treatment technique selected depends on factors such as previous methods of treatment if any, location on body, risk of recurrence and metastasis, and the volume of tissue invasion
Surgery performed to remove nonmelanoma skin cancers from areas where cosmesis is not a factor, scarring is acceptable, and patient wants to expedite results
Basal cell (BCC)
Faster growing and more dangerous than basal but not as much as melanoma; tends to metastasize
Can appear anywhere on body; common on head, neck, and other sun-exposed areas
Younger with sunburns at greater risk
1-2 million cases yearly, RT when cosmesis is ideal (face)
Treatment technique selected depends on factors such as previous methods of treatment if any, location on body, risk of recurrence and metastasis, and the volume of tissue invasion
Surgery performed to remove nonmelanoma skin cancers from areas where cosmesis is not a factor, scarring is acceptable, and patient wants to expedite results
Squamous cell carcinoma (SCC)
Cutaneous squamous cell
Basal to squamous cell ratio in men to women
5:1 men, 10:1 women
One of the most lethal forms of skin cancer and very common
Most common sites: women’s legs and men’s trunk and face, can also occur in any melanin sites such as eyes, eyelids, mucosa, oral cavity, and anus
Key to treatment is treating it before it metastasizes; palliation; cure usually limited to surgical resection
Chemo and immunotherapy to prevent metastasis or if it’s already metastasized
RT limited to palliation for metastatic dose; radioresistant but can be used adjuvant to surgery or as treatment if surgery is not an option
Superficial, electron, or total skin electron irradiation (TSEI)
Malignant melanoma
Skin cancer that usually appear as firm, non-tender, pink-red lesion; nodular
Distinction has climbed and now has its own staging system
Rare, high rate of recurrence and morbidity greater than melanoma
In sun-exposed sites
Chemo and RT combination treatment if too expensive for surgery
Merkel cell
Stanford technique: treatment with 12 fields or 6 dual fields; extend SSD to 300-400 cm to include entire body
Using electrons, patient exposed
Mycosis fungoides
Total skin electron irradiation (TSEI)
Metastatic melanoma TSEI dose
36 Gy in 9 weeks, 1 Gy per fraction, 4 days a week
5 types of surgical treatments for basal and squamous cell cancers
Often the original excisional biopsy contains all of the tumor with acceptable margins Mohs surgery Electrodesiccation Cryosurgery Photodynamic therapy
Often used to treat BCC and early SCC; with local anesthesia, the cancer is scooped out with a curette and the destruction of any remaining tumor cells and process of bleeding is carried out with a probe emitting a high frequency electric current to destroy tissue and cauterize blood vessels
Electrodesiccation
Surgery with best success rate for BCC and SCC
Mohs sugery
Instrument in the form of a loop, ring, or scoop with sharpened edges
Curette
Treatment of early nonmelanoma skin lesions with liquid nitrogen or carbon dioxide applied to a lesion, lowering its temperature and thereby freezing and killing abnormal cells
Cryosurgery
Photosensitizing agent is injected into the body and absorbed by all cells; light from a laser is directed on the tumor area and causes a reaction within the cells that contain the photosensitizing agent that destroys the cells
Photodynamic therapy
4 factors that affect the choice between the use of electrons and kV x-rays for the treatment of skin cancer
Comes down to what is in clinic, may not have superficial/orthovoltage machine; electrons come from linac
Size of treatment volume, depth of lesion
Underlying anatomical structures, use electrons if critical structure under lesion
Physician preference
_________ have poor small dose field and don’t get good dose coverage
kV x-ray photons allow the target volume to be covered with a smaller field size than with that of a field producing similar effects near the skin surface through the use of electrons because of electron field physical properties
________ get good average to high dose, sharper beam edge
Electrons, photons
Surface dose less than ___-___% is generally unacceptable; ___-___% isodose lines encompassing what is being treated (always try to get 100% isodose line to lesion)
90-95%
With photons regardless of energy, Dmax always at ________; high energy electrons = ____ surface dose, low energy electrons = ____ surface dose
Surface; high, low
Deep tissue dose ______ for photons than electrons
Electrons have rapid falloff, kV x-rays penetrate much deeper and affect a greater volume of underlying tissue
Use electrons when critical structures beneath lesion
Higher
No significant difference exists between bone and soft tissue doses for electrons
Absorbed dose is _______ in bone and cartilage than in soft tissue with the use of kV x-rays; photoelectric effect dependant on Z^3/E^3
Higher
1 cm of bone = ____ cm of tissue; 1 cm of lung = ____ cm of tissue because of density
- 65 cm
0. 25 cm
Excellent or good cosmesis in ___% of patients treated with kV x-rays, compared with ___% of patients treated with electrons
95%
80%
Cosmetic results were superior for patients in whom less than ___% of the dose was delivered with bolus; with electrons bolus _______ surface dose and _______ cosmesis
50%
Increases
Decreases
Depth at which the tangent plotted through the steepest section of the electron depth dose curve intersects with the extrapolation line of the brems tail
Range of electrons (10%), where they stop/dissipate; electrons/2
Practical range (RP)
6X loses ___% per cm; 18X loses ___% per cm
3%; 2%
Typical SSDs for photons and electrons
13-50 cm for photons
110-115 cm for electrons (typical = 105 cm), may need to increase distance for thicker/larger body part (ex: shoulder in the way)
Typical margin surrounding skin cancer, can do electrons clinically on treatment machine
For small basal cell, ___ cm margin adequate because it’s not aggressive if superficial
2 cm
1 cm
Inner ear less than ______ cGy
1000 cGy
A single dose of ______ cGy may cause cataracts
200 cGy
Inflammation of cartilage
Chondritis
3 doses to small areas of skin cancer
Small dose of 2000 cGy in 1-2 days, 1000 cGy per 1-2 fractions
3000 cGy in 5 fractions; 5-7 days, 600 cGy per day
4000 cGy in 10-16 fractions, 300 cGy per day over 16-28 days; best cosmetic result because dose spread out
Lip cancer dose
6000 cGy in 6 weeks, 250 kV
3 doses to large areas of skin cancer
4500 cGy over 15-18 fractions, 230-300 cGy per day over 21-30 days
5000 cGy over 20-25 fractions over 28-35 days
6000 cGy (60 Gy) over 20-30 fractions, 200-300 cGy per fraction; 28-40 days
Primary treatment dose for malignant melanoma
5000 cGy, 200 cGy per fraction; 25 treatments and boost with 1000-1500 cGy = 6000-6500 cGy
Connective tissue of extraskeletal system outside bone
Can arise anywhere in body, most common site: extremities, retroperitoneum, trunk, visceral areas, head and neck
Important to treat en face with these tumors because if gantry is angled tumor could be missed at depth
Soft tissue sarcoma (STS)
3 STS treatment techniques
Multimodality treatments: variety of surgery, RT, with or without chemo
Surgery: pathology and remove disease, aggressive or with combination RT and chemo
Radiation therapy
4 advantages of preoperative RT for STS
Biological effects better, scar tissue not oxygenated/hypoxia is absent
Tumor shrinkage, less aggressive surgery
Smaller treatment volume because we know no seeding/implantation; surgical contamination reduced and local control leads to smaller field size and decreased morbidity, fibrosis, etc.
Give initial dose, do surgery, and then boost with postoperative margins
2 disadvantages of preoperative RT for STS
Affects healing, wait 6 weeks before surgery
Don’t know type or whole location/extent of disease
STS margin, and boost field margin
3-6 cm margin
Boost: tumor bed and scar with 2-3 cm margin
Leave ___-___ cm margin of compartment of extremity untreated to avoid lymphedema and fibrosis
1-3 cm
Equivalent rectangular field dimensions of the open or treated area within the collimator field dimensions, actual blocked area treated
Only includes what’s being treated, doesn’t include open air
Effective field size (EFS)
Blocked field size (BFS)
Collimated field
Actual field size
Appears as multi-colored blotches/lumps on skin in HIV and AIDS patients
Kaposi’s sarcoma
Margins, energy, and dose for Kaposi’s sarcoma
1.5-2 cm margin
Low energy 4-6 MV photons
1000 cGy with boost of 2500 cGy; single dose of 700 cGy but get lasting results with 2000 cGy
Postoperative energy, EBRT dose, and dose with no preoperative regimen for STS
Low energy, max 6X; thicker area (buttock, abdomen) = 10-15 MV
EBRT: 4500 cGy, cumulative dose (CD) = 63-6500 cGy
No preop: 60-66 Gy
STS preoperative dose
4500-5580 cGy 6-8 weeks before
3 methods for postoperative boost with 50 Gy before surgery for STS
Brachytherapy (place catheters during surgery, can be removed after) with 12-20 Gy = 62-70 Gy total, about 3 days after surgery
IORT: 10-16 Gy immediately after removal of tumor = 60-66 Gy
EBRT: 16-18 Gy for microscopic disease = 66-68 Gy; 20-26 Gy for gross residual disease = 70-76 Gy
Brachytherapy source, primary treatment dose, boost dose with dose rate, and dwell time for STS
Source: interstitial iridium-192, 4-7 days after surgery
Primary: 4500 cGy
Boost: 20-25 Gy with dose rate of 40 cGy per hour
Dwell time: 2000/40 = 50-62.5 hours
Head and neck STS initial dose and electron dose
Initial: 4500 cGy (spinal cord)
Electrons: 60 Gy
Chemo drug for STS
Doxorubicin
Malignancies involving bone, connective tissue, blood vessels, etc.
Most common factor is pain accompanied by swelling, engorged veins, etc.
Important to treat en face with these tumors because if gantry is angled tumor could be missed at depth
Bone tumors
2 types of bone cancer
Primary: vast array of biological behaviors
Metastatic: more frequent
7 types of bone tumors
Osteosarcoma Chondrosarcoma Fibrosarcoma Ewing's sarcoma Multiple myeloma Giant cell tumor Metastatic bone disease
Most common osteo-malignant primary bone cancer; 2 to 1 ratio of men versus women
Radioresistant; doses necessary for a clinical response often result in tissue damage and subsequent amputation
Can use radiation if surgery not an option, cure unlikely; palliative RT for pain control to prevent spread
Osteosarcoma/osteogenic
Primary bone cancer but can occur as secondary
Most common in adults, 40% of adult bone tumors
Men to women ratio of 2 to 1
Treatment of choice is surgery, radiation doesn’t play role because it’s radioresistant but used in high doses for patients with inoperable disease
Chondrosarcoma
Rare primary bone malignancy, slight male predominance
Fibrous/connective tissue, locally aggressive
Rare disease
Wide radical excision aggressive surgery, still high rate of recurrance
Fibrosarcoma
Bone cancer most common in 1st decade of life, more predominant in males
Usually highly malignant, arises is bone diaphysis/shaft and can occur in soft tissue
Multimodality approach because of age of patients, want greatest chance of cure: surgery, chemo, and RT
Aggressive therapy including multiagent chemo and adjuvant RT has resulting in positive outcomes in adolescents; more radiosensitive than other bone tumors
Avoid epiphyseal plate or growth could be affected
Ewing’s sarcoma
Primary bone cancer, affects bone marrow plasma cells
Non-osseous (blood, etc.) arises from marrow
1.5 men to 1 woman
Usually presents as disseminated, lytic lesions
Treatment for palliation: chemo and RT; incurable but can see long-term remission
Before RT primary treatment: in localized presentation, palliate pain, prevent fracture, and spinal cord compression
Multiple myeloma
Commonly arise in metaphysis and epiphysis in long bones of young adults; extremely aggressive, benign
Usually of bone
Surgery treatment of choice; RT for inoperable disease and palliation, may need to use bolus
Giant cell tumor
Metastasizes from primary cancer (lung, breast, etc.) to bone
Commonly treated in RT clinic, increase mobility
Gives rise to pain, pathological fractures, frequent neurological problems (can lead to paralysis), and spinal compression (oncologic emergency, needs to be treated quickly to prevent loss of sensory sensation and paralysis that could become permanent)
Metastatic bone disease
4 important diagnostic tools for detection of bone sarcomas
Radiograph (most), can be mistaken as trauma and are difficult to detect
CT helps detect growth and invasiveness
MRI for soft tissue and vascular structures
Bone scans with technetium-99
Multiple myeloma TBI and hemibody (HBI) total dose, margins of spine, EBRT dose, and palliative dose with boost
TBI: 750-850 cGy; HBI: higher dose per fraction and less toxicity to marrow
Spine margins: 2 vertebral bodies above and below; ex: disease in T3-T8 = treat T1-T10
EBRT: 1500-2000 cGy
Palliative: 30 Gy and boost of 1000 cGy to smaller area
Osteosarcoma dose, and post-operative dose
Dose: 60-65 Gy in 30-35 fractions, 8 weeks
Post-op: 64-68 Gy to high risk sites, unresectable tumor up to 70 Gy
Radionecrosis at ______ cGy in 20 days or less
8000 cGy
6 adjuvant chemo drugs for unresectable osteosarcoma
Cisplatin Epidoxorubicin Ifosfamide Cyclophosphamide Etoposide Bleomycin
Chondro-
Cartilage
Chondrosarcoma dose, preoperative dose, and unresectable tumor/no surgery dose
Dose: 6000 cGy in 4-6 weeks
Pre-op: 40-55 Gy
Unresectable: 70 Gy
Radiation dose and field technique to stop recurrence of fibrosarcoma
66-70 Gy with shrinking field technique
Reduces the treated field area one or more times during the course of treatment in response to a tumor that reduces in size and/or the need to limit doses to normal structures; initial and boost field
Shrinking field technique
Giant cell tumor dose and local control rate
Dose: 3500 cGy and 15 treatments, 45-55 Gy in 5-6 weeks
Local control rate: 80%
Ewing’s dose and boost margins
55-60 Gy; initially 4500 cGy with two 500 cGy boosts, 1st with 5 cm margin and 2nd with 1 cm margin (margins with less than 5 cm show greatest recurrence, use larger fields)
Don’t want to go over ___% hot spot
110%
Isodose goes direction towards ______ of wedge
Toe
3 metastatic bone disease doses (1 with boost and 2 with lower total dose but higher dose per fraction because the patient has short time left, come in less often)
30 Gy in 10-15 treatments with 1000 cGy boost
24 Gy in about 6 fractions
20 Gy in 5 fractions = 400 cGy per fraction
2 predominant cancers of lymphoreticular system
Hodgkin’s disease
Non-Hodgkin’s lymphoma (NHL)
Spreads predictably, systemic
Reed-Sternberg cells must be present
Treatment technique: RT (less common), surgery (biopsy and possible debulking), and chemo (used in combination with RT)
Major lymph node (LN) groups can be treated with large mantle fields: AP and PA; take two separate fields
Mantle and paraaortic field treated sequentially (a few weeks) because large fields greatly tax patient (prophylactic)
Simulation: patient straight on table and in immobilization device because large fields, laser alignments coincide with axis of rotation of machine; smaller field if chemo and RT
Hodgkin’s disease
Standard treatment for stage 1 & 2 Hodgkin’s
ABVD alone or in combination with 25-30 Gy involved field irradiation
Calculates dose in an irregularly shaped field; ex: mantle field = irregular field
Clarkson algorithm
Position with patient supine, chin extended, and arms bent by side with hands on hips which puts axillary LNs away from lungs, shield lungs
Large field requires aggressive immobilization
Alpha cradles and vac-locks, minimal clothing, etc.
Akimbo
Irradiation that includes only the affected LN region
Involved field irradiation
Typical Hodgkin’s dose and energy
25-30 Gy with chemo before (ABVD, Stanford V, BEACOPP, etc.)
6-10 MV photons provides skin sparing effect, abdomen up to 15 MV
5 Hodgkin’s ports
Mantle Periaortic/para-aortic Pelvic Hockey stick Chimney
2 ports that make up the inverted Y
Periaortic/para-aortic
Pelvic
Superior/upper border follows line of mandible and cuts through tragus of ear
Inferior border at T9-T10 (diaphragm)
Lateral border: flash/extends off side to include axilla
Caudal extent tattooed because gap calculation between this and para-aortic field
Mantle port
Superior/upper border: inferior border of mantle plus calculated gap
Posterior/inferior: L4-L5 interspace/aortic bifurcation
Lateral: 5 cm off midline to include transverse processes
Can also include spleen but if resected can include splenic pedicle at T11/T12
Periaortic/para-aortic port
Bottom of ischial tuberosity (BIT) or 2 cm below bottom of obturator foramen (BOF)
Pelvic port
Treat one side/ipsilateral side of inverted Y, seminoma (testicular disease)
Hockey stick port
Port for entire pelvis
Chimney
Makes sure there’s no overlap of two fields over specific structure, ex: spinal cord
Gap calculation
Gap calculation formula
1/2(L1)(d/SSD) + 1/2(L2)(d/SSD)
5 blocks for involved-field irradiation treatment of Hodgkin’s
Initially block lungs and femoral heads for AP/PA
AP = larynx block, PA = cervical
At 1500 cGy add an apical heart block
At 3000 cGy add subcarinal heart block
At 36-3800 cGy add T-spine block on PA only
Involved-field irradiation of Hodgkin’s total dose
36-3800 cGy, 150-200 cGy per fraction usually even weighted AP/PA
Paraaortic Hodgkin’s treatment dose
36-4400 cGy
2 paraaortic Hodgkin’s treatment shielding considerations
If liver in treatment field, 50% blocking (1 HVL)
Testicular clam shield for scatter (10% of dose can get to testicles), up to 0.75-3% reduced
2 chemo agents for Hodgkin’s
MOPP: not as common
ABVD: better results and less toxic
MOPP
Nitrogen mustard
Vincristine
Procarbazine
Prednisone
ABVD
Doxorubicin
Bleomycin
Vinblastine
Dacarbazine
Disease of lymph tissue can arise anywhere lymph is travelling
Chemo with or without RT because of sporadic spread, systemic treatment works best; radiation to site of involvement
Non-Hodgkin’s Lymphoma (NHL)
Field for no mediastinal involvement; mediastinum not usually involved with NHL but if it is, can treat with mantle field
Mini-mantle field
Typical, palliative, and dose with least possibility of recurrence of NHL
Typical: 40-50 Gy
Palliative: 20-30 Gy
Least possibility of recurrence: 3500 cGy or more
Chemo drugs for NHL
Alkylating agents: CHOP or CVP
