Cervical Screening Flashcards
What percentage of human cancers are caused by viruses?
12%
What viruses are associated with the development of cancer?
HPV
HIV
EBV
HBV
When do most people pick up HPV?
In late teens/early 20s, peak prevalence 15-25 years
Why does prevalence of HPV decline with age?
Due to body clearing the virus, cervix maturing and less susceptible to changes, and reduced number of exposures to people with HPV
What is the overall prevalence of HPV?
10%
What is the prevalence of HPV in young women?
30%
What is the lifetime risk of exposure to HPV?
Up to 75% (from serological studies)
What cancers is HPV implicated in?
Cervix Penis Vulva/vagina Anus Mouth Oropharynx
Why does there need to be some break in the epithelium in order for HPV to infect the basal cells?
HPV can only infect basal cells and the basal layer is usually protected by an epithelial layer
When can HPV disrupt normal cell division and cause pre-cancerous changes?
If it becomes integrated in the nucleus
What percentage of people with HPV will clear the virus with their normal immune system?
90%
What can persistent HPV infection result in?
Viral lesions (CIN1, CIN2 or CIN3) CIN1 lesions may regress, remain unchanged or progress to CIN2, CIN3 or cervical cancer
In what percentage of patients aged 15-34 years and 35+ years is regression to CIN1 to dysplasia estimated to occur?
65% in 15-34 year olds
40% of patients aged 35 or older
How long does it take most low-grade SIL to clear?
6-12 months
What is primary prevention and secondary prevention of HPV?
Primary prevention with immunisation
Secondary prevention with cervical screening
What is the UK HPV immunisation programme?
Introduced September 2008
Girls born after 1st September 1990 are offered bivalent vaccine HPV16/18
From September 2012 - quadrivalent vaccine HPV 16/18/6/11
From September 2014 - 2 dose regime
What is the additional benefit of the high uptake of HPV immunisation in Scotland?
Herd immunity
Immunisation against HPV reduces the risk of what cancers?
CIN and cervical cancer
What countries have the highest uptake of HPV vaccination?
Countries with the lowest rates of cervical cancer are those with the highest uptake of the vaccination
What is opportunistic screening of HPV?
When a smear test is offered by chance to a woman coming into surgery/clinic for another reason
When was organised screening brought in?
1989-1991
What is the process of the Scottish Cervical Cell Recall System?
Smear taker enters request details on to SCCRS database
Vials sent to lab, receipt logged on SCCRS
Patient details received from SCCRS, vials processed, slides stained and screened
Cytology lab results put on SCCRS database
SCCRS creates colposcopy referral
Woman and GP receive results
At what ages are screening samples for cervical cancer taken?
Women aged 25-64 years
3 yearly smears up to age 50
5 years from age 50
(liquid based cytology)
What is cervical cytology?
Microscopic detection of abnormal squamous cells that are suggestive of underlying cervical intraepithelial neoplasia
Identify women that have no abnormality and those requiring further investigation
What is the method of staining used for cervical samples?
Papanicolaou method (PAP)
What percentage of cervical samples are normal?
88.5%
What percentage of cervical samples are unsatisfactory and what percentage are abnormal?
2.5% unsatisfactory
9% abnormal
What is the normal cytology of the cervix?
Squamous epithelial cells Other cells - glandular, inflammatory Benign nuclear features - small - uniform size and shape - fine regular chromatin, evenly distributed
What are the features of abnormal cytology of the cervix (dyskaryosis)?
Abnormal cells may be few
Nuclear features
- increased size and nuclear:cytoplasmic ratio
- variation in size, shape and outline
- coarse irregular chromatin
- nucleoli
Graded low or high grade dyskaryosis - reflects degree of underlying CIN
What percentage of dyskaryosis is low grade and high grade?
8% low grade (and borderline nuclear abnormality)
1.4% high grade
What is the cytology management?
If normal - routine recall at 3 years
BNA and low grade dyskaryosis - repeat in 6 months
High grade dyskaryosis - refer to colposcopy
What is done in the first visit to colposcopy?
Counselling Colposcopy Magnification and light to see cervix Exclude obvious malignancy Use of acetic acid/iodine - identify limits of lesion and size - select biopsy site - define area to treat
What are the options for management of an abnormality found in colposcopy?
Punch biopsy to make diagnosis
Return for treatment if CIN2/3
See and treat at first visit if patient is OK with this
What is the histology of the transformation zone in HPV infection?
Glandular lining cells of exposed endocervical epithelium transformed into squamous cells - squamous metaplasia
Site of HPV infection
Where precancerous changes (CIN) arise
What is the histology of HPV?
Koliocytosis
Cells with wrinkled nucleus and perinuclear halo
Multinucleation
What is the histology of cervical intraepithelial neoplasia?
Abnormal proliferation of cells in the squamous epithelium - cervical intraepithelial neoplasia
Neoplastic or undifferentiated cells fill the full thickness of the epithelium and no normal differentiated cells seen - CIN 3
Undifferentiated cells occupy 2/3rd of the thickness and only top layers show maturation to medium sized cells - CIN 2
Undifferentiated cells only occupy lowest 1/3 of epithelium and surface cells can mature to large flat cells - CIN 1
What are the risk factors for cervical cancer?
HPV, particularly types 16 and 18 Early age at first intercourse Multiple sexual partners Prolonged oral contraceptive use Cigarrete smoking STDs Immunodeficiency Persistent infection Viral DNA integration in host cell genome, over expression of viral E6 and E7 proteins, deregulation of host cell cycle
What is cervical intraepithelial neoplasia a precursor of?
Invasive cancer
Disarray in the arrangement of the cells within the epithelium, variation in cellular size and shape, nuclear enlargement, irregularity, hyperchromatism
What are the grades of severity of cervical intraepithelial neoplasia?
CIN 1
CIN 2
CIN 3
What percentage of CIN 3 progress to invasive cancer?
20-30% over 10-20 years if untreated
What does malignant change in the squamous cells of transformation zone of cervix result in?
Squamous carcinoma
What is the treatment of cervical intraepithelial neoplasia?
LLETZ - large loop excision of the transformation zone
Cold coagulation
Laser ablation
What are the functions of follow-up after treatment of CIN?
To confirm that treatment was effective - residual disease within 2 years
To prevent invasive cancer - recurrent disease in 5% after 3-5 years, detect occasional cancer
To reassure the woman
What follow up should be done after treatment of CIN?
Increased risk of cervical cancer compared with normal population
Follow up LBC at 6 months for cytology and high risk HPV
If both negative, return to recall
If either are positive, return to colposcopy
What are the aims of cervical screening?
Reduce risk of cervical cancer
Detect cervical dyskaryosis
Detect CIN
Prevent cervical cancer
How many cases of cervical cancer are there per year in the UK?
2,500
How many deaths are there due to cervical cancer per year in the UK?
1200
What is the peak age of cervical cancer?
45-55 years
What are the risks for cervical cancer?
HPV Multiple sexual partners Early age at first intercourse Older age of partner Cigarrete smoking More deprived women more at risk
What are the symptoms of cervical cancer?
Abnormal vaginal bleeding Post-coital bleeding Intermenstrual bleeding/PMB Discharge Pain
How is cervical cancer diagnosed?
Clinical presentation
Screening
Biopsy
How is cervical cancer staged?
EUA - especially rectal
PETR-CT
MRI
What are the functions of radical hysterectomy?
Exploration of pelvic and para-aortic space Removal of; - uterus, cervix, upper vagina - parametria - pelvic nodes
Ovaries conserved
What is the treatment of cervical cancer?
Radiotherapy - external beam x 20 fractions
Chemotherapy - 5 cycles of cisplatin
Caesium insertion - 24 hours, radiotherapy dose to site of tumour
What is the cure rate of stage 1a cervical cancer?
99%
What is the cure rate of stage 1b cervical cancer?
85%
What is the cure rate of stage 2a cervical cancer?
75%
What is the cure rate of stage 2b cervical cancer?
60%
What is the cure rate of stage 3b cervical cancer?
33%
What is the cure rate of stage 4 cervical cancer?
15%