HPV: What is it? What does it do?

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