Lecture 8.2: Viral Infections and Cancers Flashcards
What is an Oncogene?
Genetic material that carries the ability to induce cancer
What is Human Papillomavirus (HPV)?
• HPV is the most common sexually transmitted infection (STI)
How common is HPV?
80% of sexually active unvaccinated men and women get the virus at some point in their life
How to Test for HPV?
- Males –Only visual exam*
* Females –Visual exam and detection through smears
How is HPV Transmitted?
- More likely transmitted through direct contact
* With infected skin (i.e. wart is present)
What are Condylomata acuminata?
Benign anogenital warts most often caused by HPV types 6 and 11, as are laryngeal and oropharyngeal warts
What is the incubation period of warts?
1-6 months
Features of Visible Anogenital Warts (7)
- Soft
- Moist
- Minute pink or gray polyps
- Enlarge
- May become pedunculated
- Have rough surfaces
- May occur in clusters
Where do anogenital warts occur in men?
- Foreskin
- Coronal Sulcus
- Within the Urethral Meatus
- Penile Shaft
- Anus & Rectum
Where do anogenital warts occur in women?
- Vulva
- Vaginal Wall
- Cervix
- Perineum
- Urethra
- Anal Region
What types of HPV cause flat endocervical or anal warts that are difficult to see and diagnose clinically?
16 and 18
If untreated what can Condylomata acuminata lead to? (4)
- Transmission to sex partners and newborns
- Warts may grow and spread if left untreated
- May cause cervical cancer
- Block openings from anus, vagina and urethra
What HPV Types appear to cause Cervical Cancer?
HPV Type 16, 18, 31, 33, 35, or 39
What HPV Types most likely to cause cancer?
- HPV 16 and 18
- High Risk
Which HPV Types associated with benign warts?
- HPV 6 and 11
- Low Risk
Which cancer is HPV 16 most commonly linked to?
HPV16 is commonest in squamous cell carcinoma
Which cancer is HPV 18 most commonly linked to?
HPV18 is more associated with adenocarcinoma
Risk Factors for Cervical Cancer (6)
- Younger age at first intercourse
- A high lifetime number of sex partners
- Oral Contraceptives
- STIs
- Cigarette smoking
- Immunodeficiency
Symptoms of Cervical Cancer (8)
- Often Asymptomatic
- Irregular Vaginal Bleeding
- Pain during intercourse
- Foul-smelling Vaginal Discharge
- Pelvic Pain
- Obstructive Uropathy
- Back Pain
- Leg Swelling (due to venous or lymphatic obstruction)
- Pelvic examination may detect an exophytic necrotic tumor in the cervix
What is CIN (Cervical Intra-Epithelial Neoplasia)?
It is a term that describes abnormal changes of the cells that line the cervix
How is CIN (Cervical Intra-Epithelial Neoplasia) Graded?
1: Mild cervical dysplasia
2: Moderate dysplasia
3: Severe dysplasia and carcinoma in situ
CIN 1: Low Risk.
CIN 2 & 3: High Risk
Can CIN 3 Regress?
- CIN 3 is unlikely to regress spontaneously
- If untreated, over time it may penetrate the basement membrane
- Thus becoming invasive carcinoma
Mechanism of Action of HPV
1) Normal viral mode of infection
2) Viral DNA integrates with Host DNA
3) Alterations in genes can lead to carcinogenesis
What are the 3 different types of gene alterations HPV infection cause that may lead to carcinogenesis?
1) Loss of function of a tumour suppression gene
2) Enhanced expression of an oncogene
3) Interchromosomal rearrangements leading to altered gene expression in
involved regions
What does HPV E6 Protein do in the host cell?
Inhibits human p53 tumour suppressor protein
What does HPV E7 Protein do in the host cell?
- Anti-apoptotic effect through mutations in the p53 protein
- Rb
How is Diagnosis of Cervical Cancer carried out?
- A sample of cells is taken from the cervix for analysis
- A speculum is used to open the woman’s vagina
- Spatula to sweep around the cervix
What is the use of Cervical Screening?
A method of preventing cancer by detecting and treating early abnormalities which, if left untreated, could lead to cancer in a woman’s cervix
Histology of Determining Grade of Neoplasm: Low Grade
- If it’s well differentiated and resembles the parent normal tissue low grade
- This implies that it will grow slowly
Histology of Determining Grade of Neoplasm: High Grade
- If it’s more poorly differentiated and doesn’t resemble the normal tissue
- The implication is that it will grow more quickly than one of low grade
What is a Koilocyte?
- A squamous epithelial cell that has undergone a number of structural changes
- These occur as a result of infection of the cell by HPV
What is Loop Electrosurgical Excision Procedure (LEEP)?
- A procedure to remove abnormal cells from your cervix or vagina
- Loop is heated by an electric current to make it similar to a surgical knife
- This then removes abnormal cells and tissues from the cervix or vagina
- Medicine is applied to reduce bleeding
What percentage of oral cancers are HPV related?
25-35%
What is the most common demographic in HPV-related oral cancers?
Most common in heterosexual men in their 40s and 50s
What percentage of anal cancers are linked to HPV?
90%
What percentage of anal cancers are linked to HPV? HPV Type?
90%
70% are HPV16
Risk Factors for Developing Anal Cancer (7)
- Being over age 50
- Having another type of cancer
- Having a weakened immune system
- Regularly experiencing anal abnormalities
- Having multiple sex partners
- Engaging in receptive anal sexual activity
- Smoking
