MicroBio 160 1st Edition Lecture 15Outline of Last Lecture I. Alcohol and Cancer II. Alcohol, Tobacco SynergisticIII. Signs and SymptomsIV. 5-Year Survival RatesV. Liver Cancer VI. Staging VII. Treatments Outline of Current Lecture I. Skin Cancer Cases and Deaths II. Risk FactorsIII. Tanning BedsIV. Skin Cancer and Exposure to SunlightV. Types of UV RadiationVI. How UV damage leads to CancerVII. Types of Skin CancerVIII. Stages of MelanomaIX. Treating Skin Cancer X. BioVex Vaccine for Advanced MelanomaCurrent LectureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Skin cancer: each people over 1.0 million people in the US find out that they have skin cancer—it is the most common type of cancer in the US- 40-50% of Americans who live to age 65 have skin cancer at least once - Estimated new cases and deaths from melanoma in the US in 2010 (New cases: 68,130; Deaths 8,700)- Non-melanoma: new cases more than 1,000,000 (deaths: less than 1,000)Risk Factors for Skin Cancer:- Hereditary: people with a family history of skin cancer are generally at a higher risk of developing the disease (people with fair skin—most susceptible)- Environment: level of UV light - Multiple nevi (moles)- Occupational exposure: to coal tar, pitch, creosote, arsenic, compounds, or radium - Elevation: UV is stronger as elevation increases (thinner at higher altitudes—cannot filterUV)- Latitude: rays of the sun are strongest near the equator - Cloud cover: places with regular cover may actually reduce UVPigmentation and Risk:- Anyone can get skin cancer; however, people who have fair skin are at greater risk as well as people with red or blonde hair, light colored eyes, and freckles - Melanosome: an organelle containing melanin—the most common light-absorbing pigment found in the animal kingdom o Red melanosomes are much more reactive than black to oxidation—it takes less of a trigger like UV rays in sunlight to make potentially harmful cellular changes inpeople with red hairTanning beds and Cancer risk:- The World Health Organization moved UV tanning beds to its highest cancer risk category—“carcinogenic to humans”- UVA & UVB are present in tanning boothso Doses of UVA and UVB can be up to 10x higher in one 5 minute session than sitting outside for 4 hourso You are 75x more likely to get melanoma Skin Cancer and Exposure to Sunlight: - People should avoid exposure to the midday sun from 10am to 3pmo UV rays come in contact with skino Melanocytes produce melanin to protect the skin from UV rayso If UV rays exceed what can be blocked by your level of melanin, sunburn resultsTypes of Ultraviolet Radiation and their features: Ultraviolet Radiation Type General FeaturesUltraviolet A Radiation (UVA, long-wave UV; 315-400nm)- Not filtered out in the atmosphere- Passes through glass- Produces some tanning- Once considered harmless but now believed harmful over the long term- Levels remain relatively constant throughout the dayUltraviolet B Radiation (UVB, sunburn radiation; 280-315nm)- Some filtered out in the atmosphere by the ozone layer- Doesn’t pass through glass- Causes sunburn, tanning, wrinkling, aging of the skin and skin cancer- Highest intensity in the noon-timeUltraviolet C Radiation (UVC, short wave UV; 100-280nm)- Filtered out in the atmosphere by the ozone layer before reaching earth - Major artificial sources are germicidal lamps- Burns the skin and causes skin cancerHow UV damage leads to Cancer:- Disrupts cell communication and causes expression of stress response genes - UVB is the main cause of skin cancer (1000x more effective in causing sunburn)- Damages DNA- Oxidize lipids and produces harmful free radicals- Causes inflammation, which also produces free radicals particularly nitrogen radicals- Weakens the immune responses of the skinEffects of UV Radiation:Origins of the Three Types of Skin Cancer:- Squamous Cell Cancer: start in the middle layer of the epidermis usually affecting only the surrounding area but penetrating deeply into these tissues and gradually forming a raised patch with a rough surface- Basal Cell Cancer: originate in the lowest layer of the epidermis—the cells invade and destroy surrounding tissues, forming a painless bump or nodule that later becomes an open ulcer with a hard edge - Malignant Melanoma: the deadliest form of skin cancer—occurs when pigment making cells in the basal layer called melanocytes begin reproducing uncontrollably to distant parts of the bodyDiagnosis:- Exam of the skin and lymph nodes- Biopsy lesiono Shave, punch, incisional, excisional (only remove part of the tumor)- Mohs Surgery o Diagnostic and curativeo Surgeon removes tumor by layers o Pathologist examines each layer for clear margins o Surgeon keep cutting until clear margins are attainedNon-invasive Melanoma Cancers: usually non-invasive and non-metastatic- Basal cell carcinoma (80%)o Pearl-like greyish nodule, few mm in size, appears mostly on the sun exposed areas of the face (including the lips), scalp, neck, upper area of the chest or back, or on the back side of forearms or hands o Several nodules may merge together—a nodule may ulcerate, crust over or ooze fluid- Squamous cell carcinoma (16%)o Appears as a scaly, reddish, dome-shaped, fleshy nodule, from 5mm to few cm (ifleft untreated) in size, often with a central ulcer o Mostly appears on sun exposed areas of the skin or lips Incidence and Mortality Rates for Different Types of Skin Cancer:Stages of Melanoma: - Stage 0:melanoma involves the epidermis but has not reached the underlying dermis—this stage is also called melanoma in situ• Stage I: melanoma is characterized by tumor thickness, presence and number of mitoses, a tumor < 1mm, and ulceration status—There is no evidence of regional lymph node or distant metastasiso Stage IA: no ulceration, no mitoses o Stage IB:ulceration and/or mitoses • Stage II: melanoma is also characterized by tumor thickness and ulceration status—There is no evidence of regional lymph node or distant metastasisMelanoma:- Arise from melanocytes and are more dangerous; metastasize before tumor is noticed - Melanomas account for only 4% of skin cancers but are responsible for the majority of fatalities• Stage III: melanoma is characterized by the level of lymph node metastasis—There is no evidence of distant metastasis• Stage IV: melanoma is
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