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 of endocervix) -> 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 (ASCUS onwards)-> 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
Cervical ca screening methods
For all women who ever had sexual intercourse
25-29 y/o: PAP smear every 3 years
30-69 y/o: HPV test alone every 5 years
Cervical ca screening for immunocompromised women
For all immunocompromised women who ever had sexual intercourse
- ALL women with history of HIV
- ALL women with history of solid organ transplant
- Women on more than 2 immunosuppressants meds
25-29 y/o: PAP smear yearly
≥30 y/o: HPV test every 3 years
What is HPV vaccine?
- Viral like particle - no virus in vaccine, empty protein coat
- Offers protection from future cancer
- Prophylactic, does not treat current infection
Types of HPV vaccine
1: Cervarix (protects from HPV 16, 18)
2: Gardasil (protects from HPV 16, 18, 6, 11)
3: Gardasil 9 (protects from HPV 16, 18, 6, 11 + 5 more HPV types)
Why is there a need for HPV vaccine?
Highly effective in preventing cervical pre-cancer
How good is the HPV vaccine?
- At least 70% protection against cervical cancer
- MUST still go for regular cervical cancer screening when you are eligible
- It does not cover all cancer causing HPV infection but the most common ones with highest risks
- MUST complete injection regime to get best protection.
Is the HPV vaccine safe?
Safe
- Common S/E: pain, swelling and redness at injection site
How is the HPV vaccine given?
- Can be given to girls and boys
- Approved for use in Singapore from 9 to 26 year olds
- Most effective if given BEFORE a person becomes sexually active
- Lifetime protection. No booster currently required.
Dosing regimen for HPV vaccine
Age 9 to 14 years old:
2 dose regime (0 and 6 months)
Age 15 years old and above:
3 dose regime (0, 1-2 and 6 months)
Who will benefit from the vaccine?
BEFORE sexually active
Limited benefits observed in:
– Sexually active women
– Up to 45 years old
– Women who had abnormal pap smear
– Women who had treatment for pre-cancer cells
Colposcopy procedure
Cervix examined with low power microscopy with bright illumination
Purpose of colposcopy
- Diagnostic procedure to confirm CIN (precancerous)**/ invasive CA
- locates lesions on cervix
- indicates severity of CIN
- allows selection of sites of the lesion for biopsy
- facilitates local ablative and excisional therapy
Note: If you can already see a suspicious fungating mass on speculum exam, there is no need for colposcopy evaluation bc a punch/cone biopsy is performed instead. Colposcopy is only used for assessing margins and extent of atypical surface changes on cervix in absence of suspicious mass
Important colposcopy solutions used
Saline
- moistening and cleansing
- does not modify appearance of cervical epithelium
- evaluate abnormal blood vessels and leukoplakia before acetic acid application
Acetic acid
- denatures protein (in nucleus) of cervical epithelial cells
- abnormal cells have bigger nucleus
- the higher the dysplasia, the more dense acetowhite the lesion will appear
Lugol’s solution
- looking for poor iodine intake
- iodine stains glycogen (in cytoplasm)
- abnormal calls have smaller cytoplasm
Colposcopy features suggestive of CIN
Acetowhite
Abnormal blood vessel patterns
- Punctation
- Mosaicism
- Atypical blood vessels (microinvasion until proven otherwise)
Treatment of CIN
CIN 1 can regress back to normal
- Observation
Treat CIN 2 and 3
- Ablative therapy (LEEP) vs excisional therapy (Knife cone biopsy)
Followup
Note: CIN is precancerous condition, NOT cancer
Treat before it turns to cancer
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