Cancer diagnosis
How to recognize the disease in the early stages
Cancer causes almost every sixth death in the world. But it is possible to reduce this indicator if oncological diseases are detected and treated at an early stage. For a person, this means more chances of continuing life, for the state – less spending on the treatment of citizens. The oncologist tells about how doctors look for the first signs of cancer and why it is not always useful Igor Samoylenko.
Some types of the disease can be detected by the patient and his relatives independently, for example, melanoma of the skin or basal cell carcinoma. It is enough to have a clear idea of the structure of your own body, to understand what has been on the skin since childhood, and what appeared a couple of months ago. That is why they are called "tumors of visual localization".
In other cases, a timely visit to the doctor remains the decisive factor in the detection of a tumor. And it completely depends on the patient. Some types of cancer are so common that now everyone needs to know what measures are included in the early diagnosis.
How the disease is diagnosed
Cancer diagnostic procedures are divided into two types: invasive, which involve penetration through the external barriers of a person, and non-invasive, which do not require such intervention.
Non-invasive include imaging, that is, obtaining images of internal organs and structures of a person without incisions. It's about computed tomography (CT) and magnetic resonance imaging (MRI). In the first case, X-rays are used, which can be potentially dangerous for the patient. In the second case, the effect of magnetic fields on electrons in human tissues occurs – such a procedure is recognized as absolutely harmless.
Conventional X-rays are not used as a means of diagnosing oncological diseases: computed tomography has displaced him.
There is also positron emission tomography (PET). A person is injected with a safe radioactive substance and they observe how quickly it is excreted from the body or where and in what amount it accumulates. In this way, it is possible to determine the location of metastases at any depth and in any part of the body, even if the size of the neoplasm is only 5-6 millimeters.
Ultrasound examination also remains in the arsenal of doctors. However, in some cases, for example with colorectal cancer, ultrasound can detect the disease only in the later stages.
If we are talking about tumors of the skin, breast, intestines, lung, stomach, pancreas, liver, after receiving a picture, a biopsy and examination of the obtained material under a microscope always follow. Because this is the only way to determine whether a malignant tumor is or not, and if so, what kind it is. Until recently, it was believed that it was not worth touching the tumor and taking samples so as not to provoke its further growth, but today it is known: in most cases, the disease can spread its cells to all parts of the body at the earliest stages, and doctors' manipulations do not stimulate this process.
With the help of various kinds of punctures and incisions, doctors reach almost any part of the body to take biomaterial. If a tumor is found in the brain, oncologists will do a stereotactic biopsy.
In some cases, cancer can be detected in the early stages with the help of cancer markers. These substances appear in the body under the influence of a tumor, are characteristic of it, and normally do not occur in humans or are present in small quantities. For example, alpha-fetoprotein became one of the first cancer markers: this protein is formed during the development of the embryo and fetus, but is not normally present in an adult.
However, to date, most cancer markers have been recognized as insufficiently effective for the diagnosis of cancer. Their indicators may increase either due to other inflammatory processes, or at later stages of the development of cancer. Only prostate-specific antigen (PSA) has confirmed its effectiveness. It is used to detect prostate cancer.
Screening of different types of cancer
Screening is a set of measures to detect cancer in healthy people from risk groups. The methods that doctors choose for screening are specific to the biology of each disease.
For example, an effective way to screen for lung cancer is an annual low–dose CT scan for those who have been smoking for many years. During the study, doctors can detect a focus of the disease in the lung. If it turns out to be small, there will be a chance to cure the patient with surgery without radiation therapy or chemotherapy.
Early diagnosis of lung cancer is very important because it is the most common and most dangerous type of cancer in the world: 1.76 million people died from it in 2018.
Screening of tumors of the colon and rectum (colorectal cancer) takes place in two stages. First, doctors offer to take a stool test for hidden blood. Microscopic remnants of blood may indicate inflammation or malignant neoplasm. If they are detected, a colonoscopy should be performed.
People aged 40-75 years need to take a stool test for hidden blood every 1-2 years and, if necessary, do a colonoscopy. If the patient is found to have polyps, then examinations are prescribed more often.
Colorectal cancer is one of the most common malignant tumors as in Both in Russia and in the world. According to WHO, 862 thousand people died from this disease in 2018. People either paid attention late to blood impurities in the stool and signs of the disease such as pain, obstruction and bloating, or the disease was asymptomatic.
Breast cancer screening is aimed at detecting the disease among women aged 40-75 years. At the first stage, doctors inform the population and invite them to undergo a mammography examination. This is an X-ray examination of the mammary glands in two projections. After it, two independent groups of specialists study the obtained images. Patients whose data aroused suspicion are invited for a biopsy. For example, one patient out of a thousand may have a malignant tumor, prescribe treatment and save her life.
Cervical cancer is the second most common among women in developing countries. But with early detection, a complete cure is possible.
The only known cause of cervical cancer today is infection with the human papillomavirus (HPV). Therefore, doctors recommend that all women after the age of 21 regularly visit a gynecologist and take a smear for cytological analysis, aka PAP test (PAP test).
For early diagnosis of prostate cancer, a biochemical blood test for PSA (prostate-specific antigen) is used. If his indicator turns out to be high, the doctor will offer to do a biopsy. If cancer is detected, patients will either receive medications, or undergo radiation therapy, or in some cases undergo prostatectomy (removal of the prostate gland).
Pros and cons of screening
In Russia, the incidence of cancer has increased by 23.7% over the past ten years. The most common diseases are breast cancer and lung cancer. It is these types, as well as colorectal cancer, cervical and prostate cancer, that can be detected at an early stage, even before a person notices changes in the body or feels deviations.
However, screening is a kind of sieve. You can reach more people, and then most of them will undergo unnecessary examination, and you can – less, but then some of the patients will not be covered.
The latter is not always bad, because in some cases aggressive treatment at an early stage does not contribute to an increase in life expectancy. For example, as it turned out in In America, the detection of prostate cancer in the early stages did not lead to the fact that patients after treatment lived longer than those who had the same type of cancer found posthumously. At the same time, examination and treatment can be very painful and significantly worsen the quality of life.
Disputes arise around the early diagnosis of breast cancer. At the moment, doctors in most Western countries recommend that all women aged 40-75 years have a mammogram once every two years. However, WHO warns that even well-performed screening can give false positive or false negative results. Then, in the first case, it will cause serious concern to patients with an incorrect diagnosis: they will be subjected to unnecessary X-rays and potentially dangerous biopsies. And in case of mistakenly negative results, the woman will get false hope and will discover the disease late.
It may also happen that doctors will find a neoplasm that would not have led to the death of the patient anyway. But she will have to undergo painful treatment, which will significantly worsen her quality of life.
To date, drug technologies can seriously prolong the life or cure patients in the late stages of cancer, even if metastases have already appeared in the patient's body. Therefore, society faces the question of what is more ethical and economically expedient: to diagnose diseases at an early stage or to improve the treatment of the disease. Obviously, there is no universal answer. It is necessary to make a decision taking into account the available knowledge, resources, the prevalence of the disease and the life expectancy of patients. The answer to this question should be scientifically justified for each specific disease and society at a certain point in time.
Until then, it is important for people to weigh the risks and, in any case, continue to monitor their health. Because a cure in the late stages of cancer is possible only in places with a developed medical infrastructure. And where there is no opportunity to receive timely qualified medical care, the risk of death from cancer increases.
About the author:
Igor Samoylenko – Candidate of Medical Sciences, Senior Researcher at the N.N. Blokhin Russian Research Center of the Russian Academy of Medical Sciences.
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