Cancer Screening

Question 1

What disease characteristics are ideal for screening programs?

Answer 1

Significant effect on quality or length of life,
Prevalence is high enough to justify costs,
Effective and acceptable treatment available,
Asymptomatic period during which detection and treatment significantly reduces morbidity and mortality

Question 2

What test characteristics are ideal for screening programs?

Answer 2

Sensitive enough to detect disease during the asymptomatic period,
Specific enough to minimize false positives,
Acceptable to patients

Question 3

What characteristics of the population being screened are ideal for screening programs?

Answer 3

Sufficiently high disease prevalence, Follow-up care possible,
Willing to do subsequent diagnostic tests and necessary therapy

Question 4

What is lead time bias?

Answer 4

Lead time bias is screening patients for disease and diagnosing it earlier, which increases survival time, but mortality is unchanged.

Question 5

What is length-time bias?

Answer 5

Indolent tumors more likely to be detected by screening; probability of tumor detection related to growth rate and apparent benefit of screening is seen with more indolent tumors

Question 6

What is overdiagnosis bias?

Answer 6

Diagnosis has apparent improved rate of treatment but still no overall benefit in survival