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by mtoom


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What is the most common form of cancer?
Skin cancer
Name skin cancers in order of which are most common (3)
  • Basal cell carcinoma (most common)
  • Squamous cell carcinoma
  • Melanoma
What type of light is the most important carcinogen for the genesis of skin cancers?
Ultraviolet
What are the 3 types of UV light?
  • UVC
  • UVB
  • UVA
Which type of UV light is the most carcinogenic?
UVC

(but does not reach earth due to ozone layer)
Which type of UV light causes the most cancers?
UVB
In what ways does UVA light contribute to cancer? (2)
  • Direct carcinogenic effect
  • Photosensitizing effect
Which type of light causes sagging?
UVA
When is UVB light an important source of Vitamin D?
Summer only
Name the DNA damage event that starts a tumor and the process that causes further damage making the tumor worse.
  • Tumor induction (initial event causing DNA damage)
  • Tumor promotion (further damage) 
What is xeroderma pigmentosum?
A disease in which the repair mechanisms for UV light are damaged
  • Early death is common 
Is it true that even low doses of UVB in early life can be very important for risk in later life?
  • For which cancers? 
Yes
  • Basal cell carcinoma
  • Melanoma 
Which cancer is dependent on accumulation of very large amount of UV damage?
  • Who is at risk? (2)
Squamous cell carcinoma
  • Outdoor workers
  • Sports participants 
What can result as a result of UVB exposure?
  • What is the mechanism? 
Immunosuppression
  • Irradiation of immune cells 
  • What cells produce melanin?
  • What cells have melanin in them for protection? 
  • Melanocytes produce melanin
  • Keratinocytes contain melanin for protection
What is the most protective melanin found in all racial groups?
Eumelanin
What melanin is found in red-headed people?
  • Why is it bad? (2)
Phaeomelanin
  • Less protective
  • Intrinsically carcinogenic when activated
What does SPF mean?
Relative amount of exposure for the same burn
  • Good eumelanin (sun tan) gives what protection?
  • Blacks have an SPF of what factor from their skin?
  • 4
  • 15
How often do basal cell carcinomas metastasize?
Rarely
Where are basal cell carcinoma most common? (2 categories)
Areas exposed to sunlight (back, shoulders, chest)
  • Also along embryonal fusion plane (residual cellular instability?)
How does basal cell carcinoma manifest?
  • How about on trunk or extremities? 
Translucent nodule or plaque on the skin, with prominent telangiectatic vessels; or later, an ulcer with a raised, rolled edge
  • On trunk or extremities, circumscribed scaly red plaques 
The sclerosing variant of basal cell carcinoma looks like what?
White fibrotic scar
What are the treatment options for basal cell carcinoma? (4)
  • Electrodessication and curettage (quick and dirty, good for superficial)
  • Simple surgical excision (lowest recurrence)
  • Micrographic surgery
  • Radiation therapy (good for elderly)
Squamous cell carcinoma usually begins as what?
  • What similar condition is also pre-cancerous? 
Actinic keratosis
  • Squamous cell carcinoma in situ 
Treatment options for actinic keratoses includes what? (2)
  • Liquid nitrogen cryotherapy
  • Topical 5-fluorouracil
Actinic keratosis can develop into invasive squamous cell carcinoma
  • How does invasive squamous cell carcinoma look? 
Hard pink or white nodule, often surrounded by areas of actinic keratosis
What invasive squamous cell carcinoma metastasize?
Yes, can spread to lymph nodes and systemically
The treatment of squamous cell carcinoma is limited to? (2)
  • Surgical excision
  • Radiation therapy
What cell types do basal cell carcinoma and squamous cell carcinoma arise from?
Keratinocyte
Melanoma arises from cancer of what cell type?
Melanocyte
Melanocytes that have been damaged manifest as what? (3)
  • Freckles
  • Nevi
  • Melanoma 
All freckles are from what? (1)
Sun damage (causing activated melanocytes)
Nevi are from what? (1)
Cell division resulting in an increased number of melanocytes
  • A nevus is a "nest of melanocytes" 
What is a junctional nevus?
Nests of melanocytes at dermal-epidermal junction
What is a compound nevus?
Nests of melanocytes in both the epidermis and dermis
What is a dermal nevus?
Nests of melanocytes in the dermis
How does the most common type of nevus change throughout life?
In childhood the nevi are junctional but evolve to become dermal
What is the most significant predictor of melanoma risk?
Number of banal (common) nevi
Atypical nevi are a subset of nevi that show what?
Considerable variation in edge and color
What does variation in edge and color imply?
  • Variation in edges: Variable growth rate of sub clones of cells in the nevus
  • Variation in color: Variable melanin production 
How does the course of atypical nevi vary from other nevi?
Remain flat and youthful and extend sideways in excess of 6mm
What is bad about atypical nevi?
High risk of developing into melanoma
A tendency towards many atypical nevi is called what?
Dysplastic nevus syndrome
What kind of melanoma do nevi become?
Superficial spreading melanoma
  • Considerable variation in edge and color like a severely atypical nevus 
What kind of melanoma arises without an obvious precursor lesion?
Nodular melanoma
  • Atypical melanocyte evolves directly into melanoma without becoming an atypical nevus first 
When abnormal melanocytes expand along the dermal-epidermal junction for many years to create an expanding brown patch, what is this called?
  • Is it a type of nevus? 
Lentigo maligna melanoma (the patch is called lentigo maligna)
  • Not a nevus
How is lentigo different from other types of melanoma in terms of cancer risk?
Lentigo melanoma risk is related to cumulative exposure (whereas other melanoma risk is based on more intermittent exposure especially in early life)
What is the primary prognostic factor in melanoma?
Depth of lesion
What is the best predictor of melanoma is the general population?
Number of nevi
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