CBCL 6: Screening/Prevention

Question 1

what are the levels of prevention in the screening setting?

Answer 1

1. primary: prevent onset of condition (ex: HPV vaccine, smoking cessation)
2. secondary: detect and treat disease early to prevent morbidity and mortality (ex: screening for cervical cancer)
3. tertiary: treat established disease, preventing deterioration and reducing complications (ex: chemo, surgery)

Question 2

what are some preventable causes of cancer?

Answer 2

• occupational exposures (ex: asbestos, chemical, radiation exposures)
• infectious agents (ex: HPV vaccine, Hep B vaccine, H pylori, HIV)
• sun exposure

Question 3

what is the goal to screen for cancer? what is the gold standard for evidence and discuss harms/benefits

Answer 3

goal: reduce cancer-related mortality and morbidity; detect precursors or early disease

gold standard: prospective randomized controlled trial

screening can cause interventions that harm patients, so must consider the benefits:harm ratio

Question 4

USPSTF

Answer 4

• independent panel of non-Federal experts in prevention and EBM
• conducts scientific evidence reviews of broad range of clinical preventive health care services
• harm:benefit -> focus on health maintenance and quality of life as major benefit

Question 5

what cancers have consistently demonstrated mortality reduction in the general population?

Answer 5

breast: mammography, clinical breast exam
colon: stool blood testing, sigmoidoscopy, colonoscopy
cervical: pap test, visual screening
lung (high risk): low-does spiral CT

Question 6

what demographics are less likely to undergo colon cancer screening coverage?

Answer 6

hispanic, asian, black

Question 7

How do you, as a doctor, give a recommendation for screening?

Answer 7

must do informed decision, especially with prostate cancer and average woman breast cancer screening

patient must understand the risks, benefits and alternatives to screening

women: dense breast tissue, family history, age, menopause

Question 8

what are the risks and benefits for cancer screening?

Answer 8

risks: test itself (radiation, complications), false positives (psychological distress, incorrect treatment, more tests), overdiagnosis (psychological distress, unnecessary treatment), cost
benefits: reduced morbidity, reduced mortality, psychological reassurance, health maintenance, quality of life

Question 9

what are key modifiable targets in cancer prevention?

Answer 9

1. tobacco use
2. lifestyle: limit exposure to environmental toxins, physical activity, weight, fruits/veggies
3. screening uptake

Question 10

what is the primary role of physicians in the primary and secondary prevention processes?

Answer 10

1. facilitate smoking cessation
2. recommend lifestyle modifications
3. appropriately screen for cancer

Question 11

when should someone start and stop being screened for colon cancer? breast cancer? (average person)

Answer 11

colon cancer: 50-75 years YES, 76-85 years MAYBE, 86+ NO

breast: 40-49 EH, 50+ YES

Question 12

clustering randomization

Answer 12

so the hospitals/medical facilities can have the proper equipment for the test…decrease burden of testing

Question 13

absolute vs relative improvement?

Answer 13

absolute: take difference
relative: take difference and divide by the smaller #

Question 14

what would be affected if a population at a higher risk for the disease was screened?

Answer 14

PPV would increase

also, using risk-based screening criteria impacts PPV

Question 15

In a clinical scenario, how can a test result from a test with high specificity can be most useful? what about high sensitivity?

Answer 15

high specificity: a positive result can be used to rule in disease

high sensitivity: a negative result can be used to rule out disease

Question 16

sensitivity

Answer 16

1. ability of a test to correctly identify ppl with a disease
2. true positives/(false negatives + true positives)
3. prob of a test being negative given disease is present

Question 17

specificity

Answer 17

1. ability of a test to correctly identify ppl without a disease
2. true negatives/(true negatives + false positives)
3. prob of a test being negative given disease is not present

Question 18

PPV

Answer 18

1. probability of a person having a disease given the test is positive
2. true positives/(true positives + false positives)

Question 19

NPV

Answer 19

1. probability of a person not having disease given the test is negative
2. true negatives/(true negatives + false negatives)

Question 20

what does it mean for a cancer to be overdiagnosed? how can you tell if this is occurring?

Answer 20

pertains to slow-growing cancers; these cancers can be cured but do not need to be cured

can tell it is occurring if mortality rates remain stable despite an increase in screening and diagnosis; screening is detecting more cases but not preventing death

Question 21

smoking cessation at an individual and population level

Answer 21

individual: education to prevent uptake and smoking cessation
population: clear air acts, age restrictions and taxes