Screening for Cervical Cancer Max Brinsmead MB BS
Screening for Cervical Cancer Max Brinsmead MB BS Ph. D October 2015
Cervical Cytology n n As a screening test for Ca Cx this test has only ~75% sensitivity Better at detecting Cervical Intraepithelial Ca (CIN) » n n Must sample the squamocolumnar junction More significant if +ve in a high risk individual » » n n but then specificity is a problem Older Early sex, multiple partners, other STDs Smoking HPV infection with high risk subtype Liquid-based cytology can enhance sensitivity by ≈5% Start at age 20 or within 3 years first coitus
Cytological Terms n LGEA = Low grade epithelial abnormality » Mostly due to HPV » Also called low grade squamous intraepithelial lesion or LSIL n HGEA = High grade epithelial abnormality » Arises from CIN 1 & CIN 2 (but these are histological terms) » Also called high grade squamous intraepithelial lesion or HSIL n Both the above have “Possible” variants » That is “Possible LGEA” and “Possible HGEA”
Colposcopy n n n n Limited by need for expert and equipment Relatively expensive Subjective Limited to visible part of the Cx CIN can be masked by HPV Of most use in identifying area for biopsy Better therefore than previous alternative of cone biopsy
Histology The gold standard for diagnosis n Only as good as the sample received n » (except for cone or LLETZ) And still somewhat subjective n But accuracy is increased if stains for high risk HPV DNA is used n
Natural History of CIN n Progression 1 2 3 cancer is not inevitable n CIN 1 - 85% spontaneously regress n CIN 3 – 50% regress or stay the same n Progression time varies » n 6 m to 16 years But some will have invasive Ca when Pap smear reports only LGEA
HPV Subtyping n 90% of Ca Cx is associated with High Risk HPV » Subtypes 16, 18, 45, 31, 33, 35, 52, 58 etc n n n Highly sensitive for the detection of HGEA Does not require equipment or expertise Equivocal results can occur Of most use in the follow up of treated CIN And those patients with persisting LGEA on Pap smear From 2017 this will be the PRIMARY method of screening in Australia
Treatment Options for CIN n Observation » » n Targeted destruction » » » n Laser Diathermy Cryotherapy Excision of the Squamocolumnar Junction » » n LGEA Young women Obvious HPV infection Chronic LGEA with Low risk HPV subtype LETZ Cone Biopsy Hysterectomy
Follow up of CIN 90 – 95% will be “cured” forever n Pap smears n » Repeated until negative » 12 monthly for 2 years n Colposcopy » Ideally at least once 6 m after the procedure n HPV High Risk subtyping » Perform 12 m and 24 m after the procedure » High negative predictive value n Obstetric implications of treated CIN debatable
Current NH&MRC Guidelines Repeat Pap once 12 m after the first or if no tests for 5 years. Thereafter 2 yearly n Unsatisfactory Pap n » Treat as required » Repeat in 3 m » Send for colposcopy if 3 consecutive unsatisfactory n For LGEA » If <30 years repeat in 12 months » If >30 refer for colposcopy or repeat in 6 m n For HGEA » Send for colposcopy
Prevention of CIN and Genital Warts n Polyvalent vaccines (types 6, 11, 16 & 18) » Provide 90 – 100% protection from persistent infection, 16/18 -related CIN 2 -3, adeno. Ca in situ and Ca Cx » Also protects against genital warts caused by the low risk HPV subtypes 6 & 11 Therapeutic vaccines also under study n Optimal age for immunisation and need for boosters under evaluation n Male immunisation has started n
Counselling a Patient with a Positive Pap Smear n This is not cancer » It is pre cancer » It is the whole point of doing Pap tests i. e. to detect and treat pre cancer so as to prevent it becoming cancer » Just like watching /removing “moles” of the skin » Not all pre cancer becomes cancer n It is a common condition » 40 – 50% of ♀ not immunised at some time in their life » STD basis not helpful but may need to be addressed n The Pap test is not diagnostic » Only a well-directed biopsy can be used for Rx decisions
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