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Flashcards in Oral Cancer and Screening Deck (25)
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Define screening

Application of a test or tests to people who are apparently free from the disease in question in order to sort out those who probably have the disease from those who probably do not
Not intended to be diagnostic
Interprets the natural history of a disease at its asymptomatic stage when it is treatable and progression can be halted


What are screening programmes?

Organised screening for disease, including provision for recall, referral, specialist tx and evaluation
Screening is a continuing process
People are screened at regular intervals


What are the types of screening?

Mass population screening
- Large scale screening of population groups
- Usually by invitation

Selective screening
- Targeted screening of high risk groups

Opportunistic screening
- Examining individuals when they attend for some other, often unrelated, purpose


What are the 10 principles of screening? - Wilson and Junger 1968

1. The condition is an important health problem
2. Its natural history is well understood
3. It is recognisable at an early stage
4. Tx is better at an early stage
5. A suitable test exists
6. An acceptable test exists
7. Adequate facilities exist to cope with abnormalities detected
8. Screening done at repeated intervals
9. Chance of harm is less than the chance of benefit
10. Cost is balanced against benefit


Advantages of cancer screening?

Reduced mortality and morbidity
Reduced incidence of invasive cancers
Improved prognosis
Identify high risk groups = primary intervention
Reassurance for those screened negative
Cost savings


Disadvantages of cancer screening?

Detection of cases already incurable may increase morbidity for some patients
Unnecessary tx for lesions which may not have progressed
Psychological trauma for those with a false positive screen
False reassurance for those with a false negative screen
Reinforcement of bad habits among those screened negative


What screening programmes work?

Cervical, breast and colon cancer


Cervical cancer screening?

Women 25-64
Smears detect abnormal cells
If positive - referral for specialist exam and biopsy
Re-screened every 3 yrs until 50 and then 5 yrs


Breast cancer screening?

Women 47-73yrs
Mammogram to detect abnormalities
If positive - exam and biopsy
Rescreened every 3 yrs
2-2.5 lives saved for every overdiagnosed cose


Bowel cancer screening?

Male and females 60-75yrs, every 2 yrs
Home test for faecal occult blood to detect abnormalities
If positive - exam and biopsy
Many false positives


Screening programmes that do NOT work?

- Detected too early when not affecting health in lifetime
- High false positives = over tx

- Detected too late


Criteria for screening?

Disease must be common and serious - incidence is increasing and usually diagnosed late
Disease must have a known natural history - we do not know enough about this
A good screening test must be available
Effective tx must be available
It must be cost effective


Stages of oral cancer?

Keratosis - Dysplasia - Carcinoma


Types of oral precancerous lesions?



Leukoplakia features?

Overall about 5% become malignant within 5 yrs
About 1.5%/yr transformation
Still no reliable way to predict which lesions will develop carcinoma


Clinical appearance of early carcinoma and percentage of which progresses to cancer?

Erythroplakic 90%
Leukoplakic 58%
- All white 13%
- White and red 23%
- Stippled 21%
Ulceration 14%


How to screen for oral cancer?

Systemic visual examination of the oral mucosa
Positive screen for a white patch, red patch, ulcer of longer than 2 weeks duration


Kerala study - what happened?

Participants screened by oral examination - positives referred to hospital
Health, habits and socioeconomic date recorded


Conclusions of the kerala study at 9 years?

Oral visual screening can reduce mortality in high risk individuals BUT there was NO significant difference in the mortality rate
BUT a significant difference in men who smoke and drink alcohol in the mortality rate
= Potential of preventing at least 37,000 oral cancer deaths worldwide


What percentage of people presented with late stage disease with oral cancer?



What percentage of patients with oral cancer present late and what is the mortality percentage with no screening?

60% present late
60% mortality


What is the problem with screening for oral cancer?

Many false positives
Poor sensitivity
High specificity


Is a good screening test available for oral cancer?

Yes dentists can detect disease
But more research needed
Current research directed at using brush biopsy cytology to identify screen-detected lesions that are most likely to be dysplastic


Treatment and prognosis for oral cancer?

Prognosis is generally poor, less than 54% overall 5 yr survival
Associated with radical surgical treatment unless detected and treated early
If detected early prognosis and outcome are excellent with 90% 5 yr survival for stage 1 lesions


Is it cost effective to screen the whole UK population?

No, opportunistic screening in primary care may be cost effective