Cervical Cytology Flashcards
What are the criteria for the introduction of screening programmes
- the condition should be an important health problem - the natural history should be known
- the test should be simple safe and acceptable with known cutoff point for test values
- the treatment should be effective, leading to better outcomes with evidence based policies on who should receive treatment
- the screening programme should be known to be effective in reducing mortality or morbidity
What is the aetiology of cervical cancer?
- Rare outcome of STI
- Linked to Human Papilloma Virus (low risk types 6&11, high risk types 16&18)
- HPV DNA can be found in all invasive cervical cancer specimens
What are some risk factors of cervical cancer
- persistent infection with HPV or STI
- sexual activity from young age
- women with kate pregnancies or >5 full term pregnancies
- condoms only offer limited protection
Smoking decreases number of lanerghans cells in the cervix reducing ability to process virus
What stages happen in between normal and the cancer stage in the cervix
Low grade squamous intraepithelial lesion —> high grade squamous intraepithelial lesion
Describe the human papilloma virus
Non-enveloped
DsDNA
Circular genome (approx 8kb pairs)
Most encode 8 major proteins
How long is the average incubation period
3 weeks to a year
Can HPV infection be latent or assymptimatic
Yes, possibly years before appearance of genital warts or abnormalities
Some will be transient and may never be detected
What proteins from HPV play a massive role in immortality and malignant transformation of infected cells
E6&E7
Characteristics of low risk HPV 6 & 11
Lead to benign cervical changes and genital warts
Characteristics of high risk HPV types 16 & 18
Precancerous cervical changes
Cervical cancer
Anal and other cancers
True or false: most women are infected at some time
True
True or false: the immune system usually clears a HVP infection
True, usually, not always
What is the pathology of persistent HPV infection
Leads to loss of maturation of cervical epithelium (disrupts normal cell cycle)
Keratinocyte differentiation retarded
What are the first stages of the triage pathway
See if the pt. displays borderline/low grade dyskaryosis then do a HR-HPV test
What is the next move if the HR-HPV test is negative
Pt. returned to routine recall because it’s likely the cause of problem is non-high-risk HPV infection or not a clinically significant amount of HPV
What are some benefits of a triage
Reduces need for multiple repeat tests, women see colposcopy sooner
What’s the next move if the HR-HPV test is positive
Women referred to colposcopy
What is a test of cure
Used to assess the risk of women who test negative at follow up are at very low risk of Cervical Intraepithelial Neoplasia having residual of recurrent disease
What is standard protocol after CIN 3 detected in colposcopy
Annual follow up cytology for 10 years —> returned to routine recall
Where are cervical cytology samples taken from?
The transformation zone
What is the transformation zone
The zone between the new and old squamo-columnar junction
A method acquiring a cervical sample
Using a brush then transfer the sample to alcohol
True or false: mild dyskaryosis is heavily linked to HPV positive
True: the initial pilot study for HOV triage showed 83% showing dyskaryosis were HOV positive
Name a benefit of test if cure for cervical screening
Allows majority of women to be r freed back to routine recall directly
How does HPV attack
Micro trauma to squamous epithelial of transformation zone allows HPV to attach tit he nasal cells. The genome is then release into the cell remaining as an extra-chromosomal element until cEll reaches surface
What happens after a cell is infected with the HPV genome
The extra-chromosomal elements are packaged into virions that are lost from the surface during desquamation
What happens in the non latent case of HOV infection
Genome is incorporated, increased expression of viral protein E6 and E7 that interacted with cellular proteins to induce proliferation, eventually immortalisation and neoplastic transformation of HPV infected cells
Describe the epithelial of the cervix
Lined in 1 cell thick columnar glandular epithelial layer then the vagina lines in squamous cells, where they meet is the squamo-columnar junction