What a disease: cancer. Screening and early diagnosis

We have already told what cancer is , what factors reduce and increase the risk of developing this disease. In this article, experts at the Solo project of the Atlas biomedical holding share information on screening and diagnosis, as well as the types of malignant tumors that can be detected at an early stage.

Illustrations: Michael Kowalski

What is the difference between screening, checkout and early diagnosis?

Screening or clinical examination - a series of examinations that can detect a tumor in the absence of symptoms in humans.

Screening programs are considered effective if they reduce mortality from the disease. Mortality - the ratio of the number of dead patients to the average population. If the examination allows detecting a tumor at an early stage, but does not reduce the risk of mortality, then it is not considered effective.

The simplest example of screening is fluorography, which all adults need to undergo each year to detect tuberculosis.

Screening should be carried out in cases where it can be said with confidence that a person will benefit more than harm from further analysis, treatment, and related stress.

Therefore, when developing screening programs, the following factors are taken into account:

Tests for tumor markers are not always suitable for screening, as many of them are not sensitive enough and specific. Oncomarkers are substances whose content increases in the blood in the presence of malignant tumors. But their number may increase with inflammation, infections and benign tumors.

Screening programs differ in different countries and regions, because surveys are selected on the basis of morbidity and mortality statistics, as well as economic feasibility for the state. In the USA and Europe, a colonoscopy after 50 years is included in the list of free and recommended examinations, and in Russia it is prescribed by a doctor.

In 1985, Ronald Reagan, during a colonoscopy, revealed a large polyp (growth on the mucosa) in the intestine, which was impossible to remove during the procedure. The next day, the tumor was removed, and the news about colorectal cancer, tests and operations was published in newspapers.

You can take care of health not only with the help of state programs. Chekap - a series of surveys to check the health, which a person pays for themselves. The main goal of this service is to help a specific person, and not just reduce the overall mortality rate of the population. Therefore, a check-up on the recommendation of a doctor may include additional examinations that the state does not finance.

Early diagnosis - a case where the patient comes to a specialist with any complaints, after which the doctor prescribes certain tests and examinations for diagnosis.

For some diseases, early detection in the absence of complaints in humans is difficult. For example, there is not yet a massive screening for Alzheimer's or Parkinson’s. It is possible to establish this diagnosis only by the symptoms and results of the research.

What types of cancer can be detected early

Mammary cancer

Mammography, which the National Cancer Institute (USA) recommends for all women aged 40 to 74 years, is considered an effective screening for breast cancer.

X-rays of the mammary glands can detect tumors in the early stages, when they cannot be palpated. Also on the pictures specialist can see small accumulations of calcium. In some cases, they indicate the presence of breast cancer.

Individual screening programs may vary depending on risk factors. People with a genetic predisposition are encouraged to start screening earlier and more often than others. MRI of mammary glands is used as an additional research method.

Colorectal cancer

To reduce the risk of mortality from colorectal cancer, it is recommended to undergo a colonoscopy, sigmoidoscopy and highly sensitive analysis of fecal occult blood.

Colonoscopy is a diagnostic method that allows you to inspect and assess the condition of the rectum and colon. During a colonoscopy, the doctor can biopsy or remove potentially dangerous polyps. This is an unpleasant and rather complicated procedure, so you need to do it only with a highly qualified specialist. If there are no contraindications, you can undergo a colonoscopy under general anesthesia, for example, in the Atlas clinic. The National Cancer Institute recommends a colonoscopy every 10 years between the ages of 50 and 75.

Sigmoidoscopy is a simplified version of colonoscopy. With this diagnostic method, the doctor examines the rectum and lower parts of the colon. In a randomized clinical trial, it was found that even a single sigmoidoscopy procedure between the ages of 55 and 64 years can significantly reduce the incidence and mortality from colorectal cancer. The National Cancer Institute recommends sigmoidoscopy every 5 years from the age of 50.

Immunochemical analysis of fecal occult blood is a highly sensitive method for diagnosing latent bleeding in the lower gastrointestinal tract. Polyps and small cancers in the rectum and colon can bleed, so the analysis allows you to identify the tumor at an early stage and reduces the risk of mortality from colorectal cancer. The analysis of fecal occult blood is recommended to be tested once every 1-2 years from 50 to 80 years.

Cervical cancer

A cytology test and an HPV test reduce the incidence and mortality from cervical cancer.

Cytology or Pap test - a procedure for collecting cells from the surface of the cervix and vagina. In a smear, the size, shape, number and nature of the location of the cells are evaluated, which allows to diagnose background, precancerous and cancers of the cervix. Pap test is recommended once every three years from the age of 21. In Russia, this analysis is prescribed once a year from 18 years.

The HPV test is used to test DNA and RNA for the presence of oncogenic virus types. Using a cytology smear and an HPV test, which is performed every 5 years from 30, a specialist can detect more cervical changes that lead to cancer than after only a pap test.

Lung cancer

Screening using low-dose spiral computed tomography reduces the risk of lung cancer mortality among active smokers.

A low-dose spiral CT scan is a low-dose radiation procedure during which the X-ray unit scrolls the body. This is a sensitive screening test that displays both benign and malignant tumors, which often leads to overdiagnosis and unnecessary interventions. For this reason, this screening method is recommended only for heavy smokers who are at high risk of developing lung cancer.

Liquid biopsy can be an additional method for screening for lung cancer. The FDA has already approved a new technology for the early diagnosis and selection of the optimal treatment for this type of tumor.

X-ray and sputum cytology are not considered effective screening tests, as they do not reduce the risk of mortality.

Other types of tumors

For other types of malignant tumors, there are no effective screening programs. More research is needed to assess how surveys affect morbidity and mortality.

It is important to be attentive to changes in the body. For example, regularly check moles.

The exception to the rule is a screening for stomach cancer in Japan. This is the country with the highest incidence of stomach cancer. It is believed that this is due to the increased salt content in food and the prevalence of Helicobacter pylori infection. The state screening program has significantly reduced gastric cancer mortality, but in other countries this effect has not been achieved.

When can screening and early diagnosis be dangerous?

Despite the advantages of early detection during screening programs, this approach has disadvantages.

Overdiagnosis Detection of a tumor does not always improve and prolong the patient's life. Some types of malignant tumors may be asymptomatic and not disturb the patient. In such cases, when a tumor is detected, the patient is prescribed a series of examinations and treatments that impair the quality of life and the psychological state of the person. This explains the high suicide rate among adolescents and young people who have been diagnosed with cancer. For example, a prostate specific antigen (PSA) test reduces the risk of prostate cancer mortality, but increases the risk of overdiagnosis and unnecessary treatment. Therefore, this test is not recommended as a screening for healthy people.

Screening tests can give false results.

A false positive result is obtained if the test demonstrates the presence of a tumor, but additional examinations refute this. Such errors lead to the fact that a person once again experiences, often passes expensive and difficult medical procedures.

A false-negative result is obtained if the test does not show the presence of a tumor when it is. Therefore, the necessary patient examinations are postponed to a later date.

On the one hand, early detection can cure a tumor before it has grown. On the other hand, the detection of a neoplasm can only worsen the patient’s quality of life without improving survival. Screening is a modern problem of oncology, which requires additional clinical research, government support, an established system between the detection and treatment of malignant tumors, as well as the training of qualified specialists.

The doctor must make a plan of examinations and prescribe additional procedures - he knows what accuracy can be calculated and how to properly treat the results of screening.

Red Flags

Often the cancer does not manifest itself in the early stages, so it is important to monitor your overall health and pay attention to the changes that occur with the body.

We have compiled an exemplary list of signals in which case it is better to consult a specialist to see if everything is in order:

To identify cancer at an early stage, it is important to listen to your body, respond to signals in time and generally monitor your health. However, no one is completely immune from the disease. In the next article, Atlas will tell you what to do if cancer is diagnosed.

Source: https://habr.com/ru/post/405739/

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