Cervical Ca screening & prevention Flashcards
Squamocolumnar junction
Junction between squamous and columnar epithelium
- Plays an important role in development of the transformation zone
Main site for development of cervical cancer
Transformation zone
Development of transformation zone
During puberty -> increase in estrogen
Original SCJ moves outwards outwards (eversion) -> exposes columnar epithelium to the outside acidic vaginal environment -> cervical ectropion
‘Harsh’ environment of vagina promotes squamous metaplasia (of what is the exposed columnar epithelium) -> formation of new SCJ
Transformation zone: region bound by original and new SCJ
Human Papillomavirus (HPV)
Double stranded DNA virus
HPV 16 + 18 a/w cervical ca
Important facts about HPV infection
- HPV infections alone does NOT mean cancer
- HPV infections are TRANSIENT - PERSISTENT infection increases risk of future cervical ca
- takes up to 30 years from HPV infection to CIN to cancer
What does persistent infection mean?
Inability of body to get rid of HPV infection leading to chronic infection that eventually develops into pre-cancer then cancer over time
Risk factors of cervical ca
Increase exposure to HPV infection
- HPV infection (16/18) ++
- Multiple sexual partners
- Early age of 1st coitus < 20y/o
Reduce ability for body to eradicate HPV infection
- STI
- Smoking
- Immunosuppression
Primary prevention of cervical ca
HPV vaccination
- prevent infection from high risk HPV
Secondary prevention of cervical ca
Pap smear, HPV DNA test
- Detects presence of abnormal cells (pap)
- Detects presence of virus (HPV DNA test)
KIV Colposcopy (diagnostic test)
- Detects CIN and treatment to prevent from progressing to cancer
Pap smear
DETECTION OF CIN
- Liquid based cytology to look for abnormal cells
- SCREENING test
- For asymptomatic women
- Cervical pre-cancers are asymptomatic
- Helps with risk stratification
Sensitivity of Pap smear test
50%
Management of Pap smear result (normal women)
All cytology results require refer to colposcopy except
1. Negative for intra-epithelial lesion and malignant cells
2. Atypical squamous cells of undetermined significance (ASC-US)
- Repeat PAP in 6 months and only refer to colposcopy after 2x ASCUS
Management of HPV DNA test results
- HPV negative -> 5 yearly HPV
- HPV 16/18 +ve -> colposcopy
- HPV NON-16/18 +ve -> Do reflex cytology (PAP smear)
a. Cytology negative -> 1 year HPV
i. If 1 year HPV +ve -> colposcopy
ii. If 1 year HPV -ve -> 5 yearly HPV
b. Cytology positive -> colposcopy
*For immunocompromised women -> ALL HPV positive results refer to colposcopy
HPV DNA testing in cervical ca screening
DETECTION OF CIN
- Objective test
- SCREENING test
- HPV 16/ 18 via the Roche Cobas test
- Higher sensitivity (strong negative predictive value)
- Helps with risk stratification
2 types of HPV DNA test available
- Hybrid capture 2
- Tells you either you are positive or negative for High risk HPV only
- You will not know which type - Genotyping
- Tells you whether you are positive or negative for HPV infection and which type it is