Screening

See also: PAPP-A and Down syndrome screening

A screening test is a test that allows you to identify, in a population considered at risk for a particular disease, those subjects who are more likely to suffer from it,

directing them to specific diagnostic tests which, in case of positivity, allow to adopt early therapeutic strategies, and therefore generally effective or even preventive.

A classic field of application of screening is oncology. Many types of cancer, in fact, evolve in an extremely slow and asymptomatic or paucisymptomatic way, so that an early diagnosis is essential to increase the therapeutic and survival possibilities. An adequate screening can not only save life, cure the disease or alleviate the suffering that derives from it, but even prevent the onset of the same, for example by removing intestinal polyps or mammary nodules considered at risk of malignant evolution.

Let's now see the main screening tests in the oncology field valid for the general population:

Tumor Candidates * Screening test Breast cancer Women aged between i
50 and 69 years Bilateral mammography every two years Tumor of the
uterine cervix Women between 25 and 64 years old Pap smear every three years Tumor of the
colon rectum Men and women between 50 and i
70/74 years Search for occult blood in the stool every two years. Between 58 and 60 years rectosigmoidoscopy to be repeated every 10 years.

* in the presence of familiarity for the pathology, screening can be indicated starting from an earlier age; it is advisable to contact your doctor to evaluate the opportunity to undergo specific screening tests.

Digital rectal examination and PSA (prostate specific antigen) dosage, starting from the age of 50, are part of the screening for prostate cancer, but their validity - unlike the cases reported in the table - remains controversial.

The word "screening" is a commonly used term in modern medicine which literally means "to choose carefully". Screening is a filter to be used in the population to identify people at risk for a given disease.

The purpose of the screening test is therefore to identify those at greatest risk to whom to offer the possibility of further investigation.

If it is positive in the screening tests, as anticipated, the patient is subjected to further investigations (because he is not necessarily ill), such as colposcopy (in case of suspected cervical cancer), colonoscopy (in case of suspected cancer of the uterine colorectal), additional x-rays, breast examination and breast ultrasound (in case of suspected breast cancer).

In evaluating the opportunity for screening campaigns at the national level, it is necessary to consider a very long list of factors, such as:

the cost / benefit ratio (justifiable only for diseases of great epidemiological importance);

the risk of false positives (subjects in which the screening shows a high probability of disease, which is then denied by subsequent investigations) and related repercussions (psychological stress suffered by patients, affective and occupational consequences, etc.);

the risk of false negatives (subjects in whom the screening fails despite the actual presence of the disease) and related repercussions (false sense of security, tendency to abandon any preventive measures or not to undergo subsequent screening).

Another classic field of application of screening is obstetrics. In this sense, first of all, any infectious diseases that can cause harm to the fetus are sought, such as toxoplasmosis (toxotest), rubella (rubero-test), syphilis (lue screening), "HIV and" Herpes simplex (which fall within the TORCH ), Cytomegalovirus and a possible maternal-fetal incompatibility (Coombs test). Screening for gestational diabetes (GCT, Glucose Challenge Test), while any chromosomal alterations are typically evaluated by ultrasound (nuchal translucency), blood tests (tri-test for Down syndrome) and amniocentesis. Furthermore, immediately after the birth, the unborn child is subjected to the so-called neonatal screening, for the search for some congenital diseases, such as cystic fibrosis, phenylketonuria and congenital hypothyroidism. Once again, this type of screening is justified by the fact that the pathology is not visible at the time of birth and its execution prevents irreversible damage and death of the child due to diagnostic delays, while improving the course of the disease and the quality of life of the individual.

In addition to the traditional examples reported in the article, there are countless screening tests for other pathologies, which are however carried out only on particular populations at risk, for example for the familiarity of one or more diseases.