Lung adenocarcinoma is a malignant neoplasm originating from the glandular epithelium of the bronchial wall. In the early stages of development, it proceeds asymptomatically or with mild signs of general intoxication. Later, a wet cough, shortness of breath, chest pains are added, sometimes paraneoplastic syndrome is present. Pathology is diagnosed using imaging techniques, bronchoscopy, genetic studies, biopsy. Radical treatment is lobe, bilob, or pulmonectomy, which is supplemented by radiation, targeted or chemotherapy.
C34 Malignant neoplasm of the bronchi and lung
Adenocarcinoma (glandular cancer) of the lung occurs in 10-45% of all patients with malignant pulmonary neoplasms. It is a type of non-small cell bronchopulmonary cancer. Affects mainly the peripheral parts of the lung, differs in the degree of differentiation. A special form of highly differentiated adenocarcinoma, bronchioloalveolar cancer, is allocated to a separate group. Men get sick about 3 times more often than women. The incidence is higher among persons of the Mongoloid race. In non-smokers and patients under 45 years of age, adenocarcinoma is the most common variant of lung cancer.
Causes of lung adenocarcinoma
The causes of the neoplastic process are not fully understood. The main etiological factor is considered to be active and passive smoking. The probability of tumor growth depends on the intensity and length of smoking. Some authors of articles on oncology and pulmonology associate an increase in the incidence of glandular cancer with a high content of nitrosamines in tobacco smoke formed when using popular light “low-tar” cigarettes.
Other risk factors for the occurrence of pathology include:
- Air pollution with harmful substances. It includes unfavorable ecology, industrial and industrial hazards. The connection of the development of glandular neoplasms of the respiratory tract with inhalation of asbestos-containing dust has been established. Lung adenocarcinoma is often detected in patients who have been in contact with radon, heavy metal salts and diesel fuel for a long time.
- Genetic predisposition. Cases of occurrence of this pathology in several generations of blood relatives speak in favor of hereditary predisposition to the formation of lung cancer. Familial adenocarcinoma is formed with inherited features of carcinogen metabolism enzymes and genetically determined DNA repair disorders.
- Endogenous prerequisites. Adenocarcinoma of the lung is often formed in the area of areas of pneumofibrosis, comes from scar tissue. Such tumors are often observed in patients with tuberculosis, persons with post-tuberculosis and post-inflammatory changes in the respiratory organs. The appearance of a neoplasm is promoted by immunosuppression.
Under the influence of carcinogens, numerous gene mutations occur, leading to uncontrolled division of altered glandular epithelial cells. Adenocarcinoma more often affects the periphery of the lung. It grows slower than squamous cell carcinoma, but it metastasizes earlier. As the tumor increases in size, it sprouts the pleura, pericardium, diaphragm, spreads to the mediastinum, the adjacent pulmonary lobe. The trachea, esophagus and spine may be involved in the pathological process.
Adenocarcinoma of the lung metastasizes by lymphogenic and hematogenic pathways. The peribronchial lymph nodes are primarily affected, then the lymph nodes of the tracheal and mediastinal bifurcation, last of all, the opposite lung. Hematogenous metastases are found in the pleura, pericardium. In the later stages of the disease, second changes are most often detected in the brain, bones and liver. Macroscopically, neoplasia looks like a yellowish-brown or gray node on the incision.
Classification of lung adenocarcinoma
Adenocarcinoma is a histological variant of non-small cell lung cancer. According to the structure, there are creeping, acinar, papillary, solid and micropillary formations. Atypical forms of the tumor include colloidal, fetal and intestinal type. Depending on the presence or absence of mucus formation, mucinous and non-mucinous variants of glandular cancer are isolated. According to the prevalence of the process, lung adenocarcinoma is:
- Preinvasive. It is represented by a single formation up to 3 cm in diameter with a creeping type of growth. There is no invasion of the stroma, vessels or pleura.
- With minimal invasion. Minimally invasive adenocarcinoma differs from the previous variant by the presence of a stromal invasion of no more than 5 mm.
- Invasive. The size of the tumor is more than 3 cm. The degree of invasion exceeds 0.5 cm. The neoplasm sprouts vessels or pleura. Tumor necrosis is present.
Symptoms of lung adenocarcinoma
At an early stage of development, neoplasia does not manifest itself in any way. Sometimes there are small symptoms of the disease, which patients usually do not attach importance to. Minor shortness of breath and increased fatigue are attributed to other causes. Later, pain syndrome, dry or productive cough joins. The intensity of chest pain depends on the localization and prevalence of the process. There is an increase in pain syndrome with a deep breath, during a cough attack, laughter.
The patient is more often disturbed by a dry cough, sometimes liquid mucous sputum is released. In some forms of adenocarcinoma, a large (2 or more liters per day) amount of watery mucus is coughed up. The germination of blood vessels by a tumor is accompanied by hemoptysis, pulmonary bleeding. Difficulty breathing first occurs only with significant physical exertion, then shortness of breath gradually increases, severe respiratory failure develops.
With a secondary lesion of the pleura and pericardium, symptoms of fluid accumulation in the pleural cavity, the cardiac sac appear. A large neoplasm sometimes squeezes or sprouts the esophagus, causing dysphagia. Occasionally, adenocarcinoma is localized in the region of the apex of the lung and is manifested by Gorner syndrome, a change in the timbre of the voice and intense pain in the shoulder. Patients with glandular cancer often receive long-term treatment for prolonged pneumonia.
With the progression of the disease, there are signs of damage to the removed organs, paraneoplastic syndrome. Most often, lung adenocarcinoma is accompanied by manifestations of hypercalcemia. The patient is worried about nausea and vomiting, severe thirst. The patient loses weight, there are symptoms of dehydration, constipation. Sometimes deformations of the terminal phalanges of the fingers are found by the type of drumsticks.
Complications are detected in the later stages of the disease. Invasive lung adenocarcinoma very often causes arrosion of the vascular wall, followed by pulmonary bleeding, which in 10-80% of cases ends in death. Pathology is often accompanied by severe paracancrotic pneumonia, carcinomatous pleurisy. Secondary damage to the brain and liver leads to disruption of the functions of these organs. Bone metastases immobilize the patient.
Diagnostics of lung adenocarcinoma
Oncologists and pulmonologists are engaged in the diagnosis of the disease. When interviewing the patient, the intensity and length of smoking, the professional route are specified, the family history is taken into account. Examination and physical examination in the initial stage of the disease are uninformative. In advanced cases, symptoms of pneumonia, hypoxemia are detected. The final diagnosis is established on the basis of:
- Visualization research methods. Peripheral infiltration sites with signs of tumor growth are viewed on the lung radiograph. CT and MRI of the chest help to clarify the localization of the neoplasm, identify metastases in the regional lymph nodes, the contralateral lung. MRI, PET CT and osteoscintigraphy are used to determine remote second changes.
- Endoscopic diagnostics. Fibrobronchoscopy makes it possible to visualize a malignant tumor in the lumen of the bronchi of large and medium caliber, to detect signs of bronchostenosis. With the help of this method of investigation, washing water is taken, a transbronchial biopsy is performed.
- Lung biopsy. It allows differentiating lung adenocarcinoma with other types of bronchopulmonary tumors, determines the degree of its differentiation and histological type. The material obtained during the biopsy is subjected to molecular genetic testing, followed by the use of the results for the appointment of targeted therapy.
Treatment of lung adenocarcinoma
A malignant neoplasm can be radically cured by removing the primary tumor and lymph nodes affected by metastases. Taking into account the prevalence of the process, surgical intervention is prescribed or combined or complex treatment is carried out, including chemotherapy, immunotherapy, radiation and targeted treatment. Adenocarcinoma of the lung in the terminal stage is treated symptomatically.
As a monotherapy, the operation is used in patients with a non-invasive or minimally invasive tumor. In the latter case, if there is a risk of recurrence, the surgical technique is supplemented with radiotherapy or chemotherapy. 1-2 pulmonary lobes are removed. With locally advanced cancer, a pneumonectomy is performed. At the same time, lymph nodes affected by the tumor process are excised.
Conservative measures include radiation, chemo- and targeted therapy, and treatment with immune drugs. Adjuvant use of ionizing radiation and chemotherapeutic agents is carried out in the postoperative period, aimed at destroying the remnants of the neoplasm. Neoadjuvant therapy is prescribed before surgery to reduce the tumor mass. Conservative treatment is also carried out in patients with contraindications to surgery.
Advanced lung adenocarcinoma with distant metastases is inoperable and is treated conservatively. Targeted therapy is prescribed to patients with certain molecular genetic properties of the tumor. For this purpose, tyrosine kinase and anaplastic lymphoma kinase inhibitors are most widely used. Standard methods also include immunotherapy. Modern medicines “train” the cells of the immune system to recognize a tumor and destroy it. Clinical trials of new immunotherapeutic drugs are being conducted.
Palliative care is provided to terminal patients on an outpatient basis or in a specialized hospice department. The main purpose of such treatment is to relieve the hard-to-bear symptoms of the disease and improve the quality of life of patients. Adequate anesthesia is of great importance. Narcotic and non-narcotic analgesics are used. If necessary, cough suppressants, bronchodilators are prescribed, long-term oxygen therapy is used, psychological support is provided.
Prognosis and prevention
Early lung adenocarcinoma (preinvasive, minimally invasive stages) with timely surgical treatment is prognostically favorable. Recovery occurs in almost 100% of patients. The prognosis worsens as the disease progresses. The survival rate of patients with pathology in the last stage is extremely low. For preventive purposes, it is necessary to give up smoking, observe safety regulations when working in production with harmful conditions, and undergo preventive medical examinations in a timely manner.