MICROBIO 160 1st Edition Lecture 16 Outline of Last Lecture I Skin Cancer Cases and Deaths II Risk Factors III Tanning Beds IV Skin Cancer and Exposure to Sunlight V VI Types of UV Radiation How UV damage leads to Cancer VII Types of Skin Cancer VIII Stages of Melanoma IX X Treating Skin Cancer BioVex Vaccine for Advanced Melanoma Outline of Current Lecture I II Cervical Cancer History HPV Types III How does HPV cause Cancer IV Risk Factors V VI VII VIII IX X Prevalence of HPV Infection Pap test Colposcopy and Cervical Exam Treating Cervical Cancer Advanced Stages HPV Vaccines and Cancer These 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 Current Lecture Cervical Cancer History Epidemiologists working in the early 20th century noted the following o Cervical cancer was common in female sex workers o It was rare in nuns except for those who had been sexually active before entering the convent o It was more common in the second wives of men whose first wives had died from cervical cancer infectious agent About 20 years ago cervical cancer was linked to human papilloma virus infection Now over 100 strains of HPV are known HPV Types 100 types of HPV 23 are present in the genital tract 12 main types associated with cancer and considered high risk o 16 and 18 most common 31 33 35 39 45 51 52 56 68 69 Most women will clear an HPV infection within 9 15 months Women with persistent high risk HPV infection are 300x more likely to develop cervical cancer How does HPV cause cancer HPV gene expression timing Viruses express their genes in 2 phases early E and late L The HPV early genes E6 and E7 are associated with cancer E6 protein cause p53 tumor suppressor degradation and promotes telomerase activity E7 protein causes Rb tumor suppressor degradation HPV hides from the immune system by inserting into host DNA persistent infection Risk Factors of Cervical Cancer HPV infection Multiple sex partners Started having sex before age 18 Other STI s HIV syphilis Chlamydia Smoking Multiple pregnancies Oral contraceptives Diet Family history Low socioeconomic status Molecular genetic factors p53 Rb Prevalence of HPV Infection Currently there are around 20 million people infected with the various types of HPV in the US alone Approximately 6 2 million new cases of HPV infection occurring annually Between 75 and 80 of sexually active individuals will become infected with HPV within their lifetime Each year more than 20 000 HPV associated cancers occur in women cervical cancer is the most common About 12 000 HPV associated cancers occur each year in men oropharyngeal cancers are the most common Pap Test and Cervical Cancer gold standard for trying to detect cervical standard The pap test was developed in 1943 by Dr George Papanicolaou since then early detection of cervical cancer has greatly improved As a result cervical cancer dropped from the second leading cause of cancer deaths among American women to the 13th in the US This is the most successful screening test reducing cervical cancer mortality by 70 in the US New guidelines suggest that women should have their first Pap smear by the age of 21 or within 3 years of first sexual intercourse Pap Smear Morphology Once the test was discovered and they started implementing it Invasive cervical cancer dropped in women The test tells when the cells look slightly abnormal Dysplasia a higher nuclear to cytoplasmic ratio this means the nucleus is larger than it should be for the size of the cell Mild dysplasia the nucleus is about 3 4 times larger than it should be Moderate dysplasia the nucleus is 5 6 times larger than it should be Severe dysplasia the nucleus is taking up most of the cell Colposcopy and Cervical Exam camera that helps doctors look to see inside the cervix Once the doctor is visualizing it the doctors use a brush to try to scrape off cells to check for disease or other problems under a microscope Cervical biopsy punch small tissue samples are taken from the cervix and examined for disease or other problems o Normal cervix smooth normal tissue o Low grade CIN a little roughed up o High grade CIN more roughed up o Cancer lumps or bumps on the cervix Progression of Cervical Cancer how much of the tissue is covered with roughed up gives you an idea of how far the cancer has actually gone Treating Cervical Cancer early stages Traditional radiation and Chemotherapy LEEP Loop Electrosurgical Excision Procedure hot wire that cuts right through the tissue coagulates the tissue at the same time so there is little to no bleeding Cone of tissue can be removed carve out a channel to remove all of the tissue sent to a pathologist Cryo probe they can freeze the tissue which leads to the destruction of the abnormal cervical tissue Advanced stages For stage IIB Hysterectomy removes the uterus and may also remove the cervix total an the vagina Radical Recurrent For stage IVA or IVB pelvic externeration o Since the bladder and rectum are removed the surgeon will utilize a segment of the intestine to form a new bladder that can be drained with a catheter and he will fix what is left of the large intestine to the wall of the abdomen so that waste matter can pass through an opening in the abdomen and into a special bag HPV also causes Oral and Throat Cancer a virus contracted through oral sex is the cause of some throat cancers In Men Oral sex may cause more throat cancer than smoking o A 20 year study of throat tumors found that the percentage of oral cancer linked to HPV surged from 16 72 o By 2020 it is estimated that throat cancer from HPV will become more common than HPV caused cervical cancer HPV Vaccines and Cancer Given as 3 shots to protect against HPV infection and HPV related diseases Two vaccines Cervarix and Gardasil have been shown to protect against most cervical cancers in women Gardasil also protects against genital warts and has been shown to protect against cancers of the anus vagina and vulva o Both vaccines are available for females HPV vaccines offer the greatest health benefits to individuals who receive all three doses before having any type of sexual activity o That s why HPV vaccination is recommended for preteen girls and boys at age 11 or 12 years Gardasil HPV 6 11 16 18 Ceravex HPV 16 and 18
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