hpv: what is it? what does it do?
DESCRIPTION
HPV–What is it and what does it do? Presented by Natasha Press, St. Paul’s Hospital at the 5th Annual Gay Men's Health Summit held in Vancouver, BC on November 9th and 10th, 2009.TRANSCRIPT
HPV:What is it? What does it do?
Natasha Press
Division of Infectious Diseases
St. Paul’s Hospital
What is HPV
• Human Papillomaviruses
• Name of a group of viruses
• >100 different strains
• >30 of them are sexually transmitted
• Only infect humans
• Infect skin or mucosa
What is HPV
• HPV causes warts
• HPV causes cancer
HPV causes warts on hands/feet
• Common skin warts
• HPV types 1,2,3,4
University of Indiana Department of Pathology
HPV causes warts in the anogenital area
• Anogenital warts
• Condyloma acuminata
• HPV strains 6, 11
Risk factors for anogenital warts
• Sexual activity (any kind)
• Number of sexual partners
• Not toilet seats!
• (the virus can only be passed from one skin surface to another)
Low-risk HPV types
• Non-oncogenic = non-cancer causing
• 6, 11, 42, 43, 44
• 1, 2, 4
High-risk HPV types
• Oncogenic = cancer causing
• 16, 18, 31, 33, 35
• 39, 45, 51, 52, 56, 58, 70
HPV causes cancer
Anogenital:• Anal cancer• Penile cancer• Gynecological cancers
Oral cancer: • Tongue• Tonsil
HPV causes cancer
• Dysplasia = pre-cancer lesion
• Intraepithelial neoplasia
• Mild dysplasia → Moderate → severe → cancer
• Low-grade → high grade
Anal dysplasia
• Name depends on where the dysplasia is:
• cervical dysplasia = CIN
• anal dysplasia = AIN
• AIN 1→ AIN 2 → AIN 3
• Dysplasia has no symptoms
HPV causes cancer
Normal anal canal
AIN 1
Mild
Low-grade
AIN 2 AIN 3
Severe
High-grade
Cancer
INFECTION
CLEARANCE
PERSISTENCE
REGRESSION
INVASION
Anogenital HPV Infection
• General population: 15%
• MSM: 60%
• HIV+ MSM: ~100%
• 75% of sexually active adults have been exposed to HPV
Incidence of anal cancer
• Cervical cancer: 40/100,000
• Cervical Pap ↓ rate by 80%
• Anal cancer:
– HIV- MSM: 35/100,000
– HIV+ MSM: twice as high
Increasing rate of anal cancer1997-2005 in BC
for men aged 30-60 years
0
0.2
0.4
0.6
0.8
1
1.2
1997 1998 1999 2000 2001 2002 2003 2004 2005
Cas
es p
er 1
00 0
00
Increase in ASCC p <0.02 log linear model
Anal dysplasia
• Could screening in men reduce the rate of anal cancer?
• Progression from dysplasia → cancer probably takes years
• Anal pap?
Anal Pap Procedure
• Moistened Dacron swab
• Rotate/apply pressure to walls of canal
• Thin-prep solution
Anal Pap Results
• Negative
• Atypical squamous cells– ASCUS– ASC-H
• Low grade (LSIL)
• High grade (HSIL)
Overview of HPV
Low Risk
• HPV types: 6, 11
• Genital warts• Low-grade anal
changes
High Risk
• HPV types: 16, 18
• Dysplasia (genital, anal)• Cancer (genital, anal)• Head and neck cancers