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26 Cards in this Set
- Front
- Back
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Carcinogenesis
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Multi-step/”multi-hit” process
accumulation of mutations + genomic “instability” Less efficient DNA repair (bad helicases, etc) Many genes implicated p53, RAS, p16, p63, Patched… |
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UV radiation: acute effects
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UVA penetrates to deep dermis
-Not as effective as UVB in causing biological change -Immediate tanning UVB penetrates epidermis to upper dermis -Responsible for most biological effects -Reddens skin in ~6 hrs -Delayed Tanning -48–72 hrs UVA—photoaging; UVB—carcinogenesis Direct DNA damage (UVB) -Pyrimidine dimers (cyclobutane and 3,4 photoproducts) Indirect DNA damage (UVA) -Reactive oxygen species created(H2O2, O) Local immunosuppression with chronic exposure |
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UV radiation as a complete carcinogen
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Initiation (UVB)
-Direct DNA damage -Mutations -Affect cell cycle & division Promotion (UVA/UVB) -Reactive oxygen species -Damage biological molecules Progression (UVB) -Additional mutation load -Metastasis -Loss of apoptosis Also immunosuppression |
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p53
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Key tumor suppressor
-Halts progression into S phase of damaged cells -Promotes proofreading of damaged DNA Most commonly mutated gene in human cancer Expression elevated in Caucasians with chronic sun exposure -70% have p53 clones with missense mutation -Daily sunscreen use decreases mutations 2 fold Severe DNA damage=apoptosis -Mutated p53 clones are resistant to apoptosis |
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Skin cancer prevention/screening
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Primary
-cost efficacy? -reduce cancer incidence Secondary -treat cancer |
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Sunscreens
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“Resistant” versus “Proof”
Physical (Titanium Dioxide, Zinc Oxide) -Scatter, messy, less irritancy Chemical (avobenzone, cinnamates, salicylates) -Absorb, poor photostability (unless complexed) -?Increased risk of skin cancer?????? Ecamsule (Mexoryl SX®)---Anthelios® from L’Oreal Higher UVB protection lower UVA and vice versa No evidence use reduces BCC Good evidence use reduces SCC Some evidence use decreases Melanoma Laboratory conditions that describe sunscreen labels rarely met in reality |
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Actinic Keratoses: symptoms, prevalence
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Pink, relatively poorly demarcated, scaly patches & plaques on the sun-exposed skin
Symptomatic at times Increasing prevalence with age (>80% over 60yo) |
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Actinic Keratoses: prognosis
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Prognosis:
-Spontaneous regression -Persistence -Evolve into SCC --1-3% chance progression to invasive SCC Comparison with CIN staging SCC may occur de novo |
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Actinic Keratoses: treatment
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Cryotherapy for an isolated AK
Field treatment: -topical 5-fluorouracil cream -Imiquimod -Photodynamic therapy -TCA -Diclofenac cream -PDT Broad spectrum sunscreens -Prevents and allows resolution of AKs Surgery? |
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Squamous cell carcinoma: symptoms
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In-situ and invasive forms
Painful, erythematous keratotic plaques/ nodules sometimes with ulceration Head, Neck, arms/hands of men -Chronic ulcers -HPV link (immunosuppressed) 65-fold increased risk in organ transplant |
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Squamous cell carcinoma: risk factors
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Skin type
UV or ionizing radiation -Cumulative and recent sunlight (esp. AKs) Heredity (genomics) Arsenic exposure HPV -Immunosuppression & OTRs |
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Squamous cell carcinoma: treatment
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Standard Excision
Curettage and Electrodesiccation Mohs Raditation Therapy Imiquimod |
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Basal cell carcinoma: incidence and syndromes
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Most common malignancy period
Incidence near 2 million annually 80% of all nonmelanoma skin cancer Rare Syndromes: Gorlins(BCNS) -Rombo -XP -Bazex -Albinism(OCA1-4) |
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Basal cell carcinoma: risk factors
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Risk factors: skin type, UV or ionizing radiation exposure, heredity, arsenic exposure, immunosuppression?
**10 fold increase for 2nd BCC** Many flavors: nodular, pigmented, cystic, superficial, morpheaform |
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Basal cell carcinoma: treatment
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Curettage and Electrodesiccation
Standard Excision Mohs Radiation therapy Imiquimod |
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Mohs surgery
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Excision with margin control
99% cure long term Tissue sparing -2 vs 4-6 mm margins Abused? Fellowship training Indications: -Recurrent tumors -Location (peri-nasal, orbital, auricular, oral, hands, genitalia) -Indistinct margins -Aggressive histology (high recurrence risk) |
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ABCDE of melanoma
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Asymmetry
Border Irregularity Color variation Diameter Evolution |
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Lentigo maligna melanoma
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Most occur on the face
Usually start as a noninvasive process Any thickening suggests the progression to invasive melanoma |
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Superficial spreading melanoma
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Nevi may meet criteria
History of change or symptom most important |
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Nodular melanoma
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Isolated nodule without typical pigment spread
Poor prognosis |
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Nodular melanoma
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Isolated nodule without typical pigment spread
Poor prognosis Starts deep (bad) Measured by Breslows depth |
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Acral-letiginous melanoma
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Melanoma of the volar hands and feet
Radial growth first Starts deep |
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Nail bed melanoma
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Variant of acral-lentiginous melanoma
Manifested by streaks of pigmentation on the nail as well as pigmentation emerging from under and around the nail |
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Melanoma prognosis
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Breslow thickness
Ulceration Mitotic rate Regression |
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Melanoma treatment and excision margins
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Surgical treatment
Adjunctive therapy Early identification and removal are key Appropriate surgical margins determined by tumor thickness The thicker the tumor, the worse the prognosis No controlled study has shown elective lymph node dissection improves survival Recurrence has been noted decades after removal Tumor depth -in situ: .5cm -0-2 mm: 1cm ->2 mm: 2 cm |
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Sentinel lymph node biopsy
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No overall survival benefit demonstrated
Provides prognostic and staging information Significant morbidity with basin dissection Less sensitive in older patients with deep breslow depth disease In the end, a highly individual decision |
