cancer screening

Question 1

what is screening

Answer 1

tests done among people who are apparently well to identify those at an increased risk of a disease or a disorder

Question 2

is screening diagnostic

Answer 2

no

Question 3

WHO’s 10 screening principles

Answer 3

1. Condition should be an important health risk
2. natural history should be understood
3. recognisable early stage
4. must be beneficial to treat it early
5. needs to be a suitable test
6. acceptable test
7. need adequate facilities for diagnosis and treatment
8. repeat screening at interval for disease of insidious onset
9. physical and psych harm should be less than the benefit of detection
10. balance costs against benefits

Question 4

how do you calculate % of patients with the disease that test postiive

Answer 4

sensitivity = Test Pos / (Test Pos + False Negative)

Question 5

how do you calculate the % of patients without the disease that test negative

Answer 5

specificity = Test neg / (Test neg + false pos)

Question 6

how do you calculate the % of patients with positive tests that actually have the disease?

Answer 6

positive predictive value of a positive test result (PPV) = Test Pos / (Test pos + False pos)

Question 7

how do you calculate percentage of patients with negative test who do not have disease

Answer 7

Negative predictive value of a negative test result (NPV) = Test N / (Test N + False N)

Question 8

how to calculate prevalence

Answer 8

disease present / total population

Question 9

8 features for the ideal screening test

Answer 9

1. simple
2. cheap
3. easily repeatable
4. easy and unambiguous to interpret
5. no false pos
6. no false neg
7. acceptable
8. benefits outweigh the harms

Question 10

5 additional factors for successful screening programmes

Answer 10

1. training
2. education
3. mass awareness
4. quality assurance
5. finances

Question 11

downside to screening (6)

Answer 11

1. person is labelled as increased risk of cancer
2. psychological impact
3. impact of turnaround times
4. successes depends on uptake
5. impact of social media
6. financial considerations for people attending screening

Question 12

what is the only technique which has been shown to reduce breast cancer mortality in the population?

Answer 12

mammographic screening

Question 13

facts: NHS breast screening programme (3)

Answer 13

1. for women 50 and over
2. includes a fully funded training programme
3. mammograms are double read

Question 14

what does an abnormal mammogram pick up?

Answer 14

lumps, calcification including micro calcification

Question 15

stats for two-view mammography

Answer 15

42% more small invasive cancers detected, 3% more in situ cancers detected

Question 16

what happens after an abnormal mammography

Answer 16

biopsy for a diagnosis, MDT (multi-disciplinary team) discussion for correlations

Question 17

Facts: Cervical screening programme (4)

Answer 17

1. method of treating early abnormalities which could lead to invasive cancer
2. 1st stage is HPV primary screening and liquid based cytology
3. sample of cells is taken from the cervix for analysis
4. early detection and treatment can prevent 75% of cancers developing

Question 18

when do you start cervical screening

Answer 18

25yrs - every 3 years until 49 and then every 5 years until 64

Question 19

as of Jan 2020 what is now the 1st test on a cervical screening sample

Answer 19

high risk HPV testing, then its cytology triage

Question 20

Primary HPV screening

Answer 20

uses HR-HPV (high risk HPV) testing as the 1st test, cytology becomes the triage test - only used when HR-HPV is found. 1 report issued with all the results

Question 21

what is dyskaryosis

Answer 21

the changes in a cervical cell

Question 22

out of the women screened annually what % have moderate or severe dyskaryosis?

Answer 22

0.7%

Question 23

what do the majority (70-90%) of bowel cancers develop from

Answer 23

benign adenomatous polyps lining the bowel wall

Question 23

what happens after an abnormal HPV triage

Answer 23

LBC, if that is also abnormal then a biopsy for diagnosis

Question 24

what is the sequence in which a benign polyp develops into bowel cancer

Answer 24

the adenoma-adenocarcinoma sequence - it takes 10 years

Question 25

aims of bowel cancer screening (3)

Answer 25

1. detect bowel cancer at an early stage when treatments is more effective 2. look for occult blood in stool 3. detect polyps

Question 26

when is bowel cancer screening offered

Answer 26

every 2 years to people aged 60-74, there's also a one off test called bowel scope screening which is at 55

Question 27

what is the FIT test

Answer 27

Faecal Immunochemical test

Question 28

what does the FIT test do

Answer 28

uses antibodies that recognise human haemoglobin

Question 29

Advantages of FIT test

Answer 29

1. detects only human blood 2. associated with higher programme uptake 3. objective numerical result 4. 1 sample required 5. more sensitive than gFOB

Question 30

gFOB as a test for bowel cancer compared to FIT

Answer 30

recognises haem component of any haemoglobin: tests for pseudo-peroxidase activity

Question 31

what is the gFOB test

Answer 31

guaiac test which the participant smears small samples of stool from 3 different bowel movements onto the FOB test card

Question 32

why are 3 bowel movements needed for the gFOB test

Answer 32

bowel cancer bleeds intermittently

Question 33

Bowel scope screening

Answer 33

thin, flexible tube with a camera is used to look inside bowel (flexible sigmoidoscopy)

Question 34

what happens after an abnormal FIT test

Answer 34

colonoscopy and biopsy interpretation, double contrast barium enema

Question 35

PSA test for prostate cancer

Answer 35

1. organ specific 2. product of prostatic epithelium 3. minute amounts found in serum 4. normal range 0-4ng/ml

Question 36

what does PSA stand for

Answer 36

prostate specific antigen

Question 37

how useful is raised PSA

Answer 37

for cancer: 80% of those w cancer have raised PSA, shows tumours of large vol and that are well differentiated for benign prostatic hyperplasia: 25-30% of men with BPH have raised PSA

Question 38

how useful is low PSA

Answer 38

20-40% of patients with organ-confined prostate cancer have a low PSA