Lung cancer
Causes and types
European Clinic, Naked Science
The latest WHO global study is published in the Cancer Journal for Clinicians and shows up-to-date statistics on oncological diseases: more than 18 million new cases worldwide, of which about two million are registered for lung cancer.
Most cancer cases are detected in Asia – 63.3% of cases on the planet, partly because about 60% of the world's population lives there. The most common types of cancer pathology in the world are lung tumors (11.6% of the total number of cases), as well as breast cancer in women and colon cancer. Lung cancer is also the most common cause of cancer mortality (18.4% of the total) due to the low level of curability of this type.
Among men, lung tumor is the main culprit of death in most countries of Eastern Europe, Western Asia (especially in the former Soviet Union), North Africa and some countries of East Asia (China) and Southeast Asia (for example, Myanmar). Among women, the highest incidence rates are observed in North America, Northern and Western Europe (especially in Denmark and the Netherlands), Australia and New Zealand.
Types of lung cancer
Lung cancer or, as it is also called, bronchogenic cancer, is a malignant neoplasm of the lungs originating from the epithelial tissue of the bronchi of various calibers. It can be central, peripheral or massive, that is, mixed, depending on the place of formation.
There are two main types of lung cancer: small cell, which accounts for about 15% of all cases, and the more common – non-small cell, which is about 85%. They differ not only in the way of growth and spread, but also in the method of treatment.
Types of non-small cell carcinoma
Adenocarcinoma is the most common type of non–small cell lung cancer, it accounts for about 50% of all cases of the disease. The tumor in this case develops from special cells in the lung that produce mucin (the mucous secret of this organ).
Most often there are several foci on the surface of the lung at once. Interestingly, this type of lung cancer is most common in non-smokers and in women. Squamous cell carcinoma accounts for about 30% of cases of non-small cell lung carcinoma.
Unlike adenocarcinoma, squamous cell carcinoma develops more often in the central areas of the bronchi in the lungs. There is a close relationship between this type of lung cancer and smoking, and this type of disease is more common in men than in women.
Large cell carcinoma, sometimes called undifferentiated, is the most rare type of non–small cell lung cancer (10-15% of all cases). As a rule, large cell carcinoma grows into lymph nodes and other organs of the body. There are also cases of lung cancer in which several types are present simultaneously or even all at once.
Small cell carcinoma
It is small cell cancer that is responsible for the horrifying statistics: it belongs to the most malignant tumors. This type of oncopathology is characterized by a short history, latent and rapid course, early metastasis and poor prognosis.
In the vast majority of cases, small cell lung cancer develops in smoking patients, more often in men. The greatest incidence is recorded in the age group of 40-60 years. There are oat cell, spindle cell and pleomorphic bronchogenic cancers.
All types of small cell carcinoma most often have an unfavorable prognosis, even in cases where the diagnosis was made at an early stage. As for treatment, small cell carcinoma responds well to radiation and chemotherapy, and surgical methods are used minimally.
Causes of occurrence
Of course, lung cancer is directly related to smoking. The incidence of bronchogenic cancer, depending on the region, may differ by 20 times, which largely reflects the development of the tobacco epidemic and differences in the historical traditions of tobacco use, the type of cigarettes and the degree of inhalation.
Moreover, the situation is aggravated by an increase in the length of nicotine addiction, an increase in the number of cigarettes smoked per day and the age of the patient. Namely, the degree of risk is directly proportional to the number of years during which a person smokes. On average, carcinogenesis – the development of cancer – in a smoker takes about 15 years.
But smoking is not the only reason. For example, the WHO report noted that the incidence rates among Chinese women (22.8 per 100 thousand) do not differ from those among women in some Western European countries (for example, in France, 22.5 per 100 thousand), despite significant differences in the prevalence of smoking between these population groups.
It is believed that although smoking is not common among Chinese women, the high incidence of lung cancer in them is associated with exposure to smoke from burning charcoal for heating and cooking.
Heredity and harmful working conditions (contact with arsenic, nickel, chromium) are also considered triggers for the occurrence of oncopathology. The background on which lung cancer most often occurs may be transferred tuberculosis of the respiratory system or chronic obstructive pulmonary disease.
And air pollution is also directly related to lung cancer pathology. For example, in industrial areas with mining and processing industries, people get sick three to four times more often than in remote villages.
Diagnostics
Unfortunately, there is a big problem with early diagnosis of lung cancer. Usually its symptoms are similar to many other diseases: incessant cough, which increases with time, chest pain, shortness of breath, wheezing or hoarseness, chest pain, which increases on inspiration, frequent bronchitis and pneumonia, loss of appetite and weight loss.
The appearance of at least one of these symptoms is a reason to consult a doctor. Timely examination makes it possible to exclude the presence of a cancerous tumor in the lungs or to detect it at the stage when treatment in the vast majority of cases gives a positive effect.
But since the early signs of lung cancer don't seem so scary, most people just ignore them. The most noticeable and frightening symptoms are coughing with blood, an increase in lymph nodes above the collarbones and a violation of the swallowing process. However, with such manifestations, in most cases, cancer is diagnosed already at the third and fourth stages.
As a result, in Russia, 25-30% of tumors are diagnosed at the first and second stages, and 70%, unfortunately, at the third and fourth, when the probability that treatment will give a positive result is not so great.
The most well–known way to detect lung cancer is to do an X-ray. However, this method is not always effective in the early stages of the disease, when the tumor is very small or atypical of its location. For a more accurate determination, computed tomography (CT) or magnetic resonance imaging (MRI) is prescribed.
These studies can identify the primary tumor focus, assess the presence of regional and distant manifestations of the disease (metastases), which is extremely necessary for staging the tumor process and deciding whether surgical intervention is appropriate.
Laboratory methods such as the determination of tumor markers are also important at the stage of initial examination, but do not play a key role. After that, it is necessary to determine the type of tumor.
Endoscopic techniques are one of the main ways to obtain tumor material, which, in turn, is the key to personalized selection of treatment in each individual case. At a minimum, you need to perform a bronchoscopy and a biopsy.
If the tumor is inaccessible for bronchoscopy, various puncture techniques are used, in which a puncture is made through the skin and, if technically possible, tissue samples are taken.
But today there are two least invasive techniques for obtaining tumor material with minimal risk: puncture of a tumor or a tumor lymph node under ultrasound control from the lumen of the esophagus or trachea. These techniques are used when the tumor has a peripheral localization and is not available for conventional bronchoscopy, or when there are enlarged lymph nodes.
They help to get tumor tissue, as well as stage the tumor process. Biopsy (biomaterial obtained by biopsy. – Approx. NS) is examined under a microscope and determines whether the tissue is malignant or not. If the tumor is malignant, then additional studies are carried out to determine how quickly it can grow and spread.
An important and most advanced method of examination is to determine the presence of mutations in genes, on the basis of which it is possible to choose personalized chemotherapy.
Treatment
The therapy of bronchogenic cancer depends on the type and stage of its development. Surgical treatment is used in situations where the tumor has clear boundaries and can be removed simultaneously along with the nearest lymph nodes.
At the zero stage – the so–called non-invasive cancer, when cancer cells are detected only in the inner lining of the lung - the treatment is quite simple and the prognosis for life is favorable. Such a tumor is found, as a rule, accidentally, during the treatment of another lung pathology.
In other cases, treatment should be comprehensive and prescribed individually. And only a detailed examination, which necessarily includes endoscopic methods, helps to choose it correctly.
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