Cervical Cancer Flashcards
What is HPV?
Human papilloma virus
What does HPV cause infections of?
Skin & mucous membranes
How is HPV spread?
HPV strains spread through childhood from direct skin-to-skin contact may lead to common warts (e.g. veruccas)
Other strains are sexually transmitted
How are the sexually transmitted strains of HPV split up?
Low risk groups - cause benign anogenital warts
High risk/oncogenic group - account for maj of cervical cancers
What are the low risk strains of HPV?
HPV 6/11
What are the high risk strains of HPV?
16/18
How can we prevent HPV?
Active HPV vaccination in teenagers
How do you cure HPV infection?
You cannot
It is persistent after primary infection (in infected basal cells of the mucosal skin)
What is the lifetime exposure of HPV?
Up to 75%
When is the peak prevalence of HPV infection?
15-25y
What % of cervical cancers are caused by HPV?
> 99%
What other cancers can HPV cause?
Penile, vulva/vaginal, mouth, oropharynx
What is the aetiology of HPV infection leading to cervical cancer?
Micro-abrasion of cervical lining –> HPV invades basal cells where they stay for many years
Virus begins to mix with cells DNA & replicates & invades other cells (can be picked up as pre-cancerous)
Cells become damaged & disorganised –> high risk lesion
High grade pre-cancerous lesion grows & occupies whole thickness of skin
All cells infected & completely disorganised –> invasive cancer that can break through the skin & spread to other parts of the body
Early HPV infection may be accompanied by _______
Mild changes in epithelium
What is an abnormal growth of squamous cells known as?
Squamous intraepithelial lesion (SIL)
Can be high grade/low grade depending on how much of the epithelium is effected & how abnormal the cells look
Abnormal cells in the cervix can be detected by _____ and are classified as _________ graded:
Biopsy/histology
Cervical intraepithelial neoplasia
Graded 1 to 2 based on how much of the cervix is affected
Persistent infection with __________ is req for the development of cervical cancer
ONCOGENIC HPV types
How do the CIN lesions progress?
CIN 1 may regress or progress to CIN 2/3 or cervical cancer
What happens to most low grade SILs?
They clear within 6-12m (probably due to immunological intervention)
Small % progress to high grade SIL (which is assoc. with CIN 2/3 at biopsy)
What % of CIN 2/3 progress to carcinoma?
40%
Which strain of HPV has the most oncogenic potential?
16
What cohort are vaccinated against HPV?
Girls born after 1st September 1990
What is in the HPV vaccine?
Now quadrivalent
HPV 16, 18, 11, 6
So prevents genital warts too
When is the HPV vaccine given to girls?
12-13 years in school
Girls who have not been vaccinated have the same level of protection as those who aren’t. Why is this?
Such high uptake of vaccine
What is involved in the process of cervical screening?
Receive invitation via mail if registered with a GP practice
Done by Scottish Cervical Call Recall System
Smear taken, details entered on SCCRS
Slides stained & screened
Cytology puts result on SCCRS
During screening - small brush is used to collect some cells from the surface of the cervix which can be sent for liquid cytology
What is the endocervix?
Luminal cavity within cervix forming a passage between the external and internal Os
What sort of epithelium covers the endocervix?
Glandular, columnar
What covers the ectocervix?
Non-keratinising squamous epithelium