Oral Cancer and Screening Flashcards
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
- The condition is an important health problem
- Its natural history is well understood
- It is recognisable at an early stage
- Tx is better at an early stage
- A suitable test exists
- An acceptable test exists
- Adequate facilities exist to cope with abnormalities detected
- Screening done at repeated intervals
- Chance of harm is less than the chance of benefit
- 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
Costs
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?
Prostate
- Detected too early when not affecting health in lifetime
- High false positives = over tx
Lung
- 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
Erythroplakia
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?
81%
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
