Flashcards in PH: Cancer Screening Deck (9):
What is meant by 'lead-time bias'?
The length of time between the detection of a disease and its usual clinical presentation and diagnosis
What is meant by 'length-time bias'?
The apparent increase in survival due to the tendency to selectively detect slowly growing cancers at screening examinations instead of typical cancers
Measures the average time from diagnosis to death, not the number of deaths. Example: how long someone will live after being diagnosed with breast cancer is their survival
Measures the number of deaths in a given population. Example: mortality is when in 1,000 women of 50-54 ages, the number of women who will die from breast cancer each year
How can you avoid length-time and lead-time bias in cancer screening results?
By using mortality from the cancer in question as an end-point instead of survival
Describe the screening programme for breast cancer
2 view mammography every 3 years women aged 50-69
Describe the screening programme for cervical cancer
Cervical smear every 3-5 years for women aged 25-64
Describe the screening programme for colorectal cancer
Faecal occult blood examination every 2 years for those aged 50-69