For a screening program to work there must be a burden of disease state that warrants such a process, there must be a preclinical phase that screening can detect, the preclinical phase is subject to intervention that improves outcomes and should be cost effective.
The purpose of screening is to prevent or delay, by means of earlier detection, the development of advanced disease and its adverse effects.
Entails the evaluation of individuals who are asymptomatic but at risk to develop advanced forms of the target disease.
The goal of screening is to detect diseases at a stage when it is not causing symptoms and when treatment it will be most successful.
Screening h should have the benefit of increasing life expectancy and increasing quality of life.
False positive results should be low to prevent unnecessary additional testing.
Screening should improve outcomes, be scientifically validated, be of low risk, reproducible, accessible, and cost-effective.
Optimal cancer screening should be followed by an increase in the rate of early disease followed by a decrease in regional disease while the overall detection rate remains constant.
Obese patients receive preventative services less often than normal-weight people.
All adults aged 20 years or older, a fasting lipoprotein profile should be obtained once every 5 years.
A significant proportion of patients with advanced cancer undergo cancer screening tests that do not have any meaningful likelihood of providing benefits (Sima CS et al).
The expected positive outcomes anticipated from some screening programs have not materialized such as with thyroid cancers or with the screening for attention deficit/hyperactivity disorders: associated with over diagnosis.
In these settings overdiagnosis has limited medical benefit for the patient that may even result in harm.
In a Danish randomized trial and median follow up of more than five years a comprehensive cardiovascular screening program did not significantly reduce the incidence of death from any cause (Let indholt JS).
Just 14.1% of cancer cases in the United States are diagnosed through recommended screening tests.
Most cancers are found when someone seeks medical attention for something else.
Only breast, cervical, colorectal, and lung cancer have screenings recommended by the U.S. Preventive Services Task Force.
Of those, the percentages of cancers found by screening:
•61% of breast cancers
•52% of cervical cancers
•45% of colorectal cancers
•3% of lung cancers
Screenings detect 77% of prostate cancers.