Lung cancer – a malignant tumor arising from the bronchi or lung parenchyma tissue. Symptoms which may suggest lung cancer are low-grade fever, blood-streaked sputum cough, shortness of breath, chest pain, weight loss.
The development of pleurisy, pericarditis, superior vena cava syndrome, pulmonary hemorrhage is also possible. An accurate diagnosis requires X-ray and CT scan, bronchoscopy, sputum and pleural fluid tests, biopsy of the tumor or lymph nodes.
Radical treatment of lung cancer includes resection methods, depending on the size of the tumor, in combination with chemotherapy and radiotherapy.
- Causes of lung cancer
- Classification of lung cancer
- Symptoms of lung cancer
- Diagnosis of lung cancer
- Treatment of lung cancer
- Prediction and prevention of lung cancer
Lung cancer – a malignant tumor of epithelial origin, evolving from the mucous membranes of the bronchial tree, the bronchial glands (bronchogenic carcinoma) or alveolar tissue (pulmonary or pneumonic cancer). Lung cancer is the most common cause of cancer-related death. Despite the progress made by modern medicine, the mortality rate in lung cancer accounts for 85% of the total number of cases.
Lung cancer development is not the same for tumors of different histological structure. Differentiated squamous cell carcinoma is characterized by slow development; undifferentiated carcinoma develops quickly and gives extensive metastases. The most malignant course is shown in small cell lung cancer: developing secretly and rapidly it starts to spread early and leads to a poor prognosis. Most of the tumors occur in the right lung – 52% of cases, while in the left lung in the 48% of cases.
The cancer is localized predominantly in the upper lobe of the lung (60%), less frequently in the lower or middle lobes (30% and 10% respectively). This is explained by a more powerful air exchange in the upper lobes, as well as features of the anatomical structure of the bronchial tree, in which the main bronchus of the right lung is a straight continuation of the trachea, and the left bronchus meets trachea at an acute angle in the bifurcation zone. Therefore, carcinogens, foreign bodies, smoke particles rush to well-aerated areas and staying there for quite a long period of time, which causes the growth of tumors.
The spread of lung cancer occurs in three ways: lymphatic, hematogenous and implantation.
The most common is lymphatic metastasis of lung cancer in bronchopulmonary, pulmonary, paratracheal, tracheobronchial, bifurcation, periesophageal lymph nodes. During the course of lymphatic metastasis first the pulmonary lymph nodes are affected in the area of separation on the bronchus lobe into segmental branches. Then, the metastases spread to the bronchopulmonary lymph nodes along the lobar bronchus.
Later, metastases travel to the lymph nodes of the root of the lung and an azygos vein and to the tracheobronchial lymph nodes. Next, the pericardial and periesophageal paratracheal lymph nodes are affected. Distant metastases occur in the lymph nodes near the liver, mediastinum and supraclavicular area.
Hematogenous metastasis of lung cancer occurs when the tumor invades the blood vessels, in which case it mostly affects the other lung, kidneys, liver, adrenal glands, brain, and spine. Implantation spread of lung cancer is possible via pleura in case the tumor invades it.
1Causes of lung cancer
Factors and mechanisms of development of lung cancer do not differ from the etiology and pathogenesis of other malignant tumors of the lung. In the development of lung cancer the main role is played by exogenous factors: smoking, air pollution by carcinogenic substances and radiation exposure (especially by radon).
2 Classification of lung cancer
According to the histological type there are 4 types of lung cancer: squamous, large cell, small cell and glandular (adenocarcinoma). Knowing the histological type of cancer is important for the choice of treatment and prognosis. It is known that squamous cell lung cancer evolves relatively slowly and usually does not give early metastasis.
Adenocarcinoma is also characterized by a relatively slow development, but it shows an early hematogenous dissemination. Small cell and other undifferentiated types of lung cancer are fulminating and are followed by an extensive early lymphatic and hematogenous spread.
It is noticed that the lower the degree of differentiation of the tumor, the more malignant its course.
By location as related to the bronchus lung cancer can be central, arising in large bronchi (the main, lobar, segmental) and peripheral, arising from subsegmental bronchi and their branches as well as alveolar tissue. Central lung cancer is more common (70%), than peripheral – (30%).
Central lung cancer occurs in 3 forms: endobronchial, peribronchial nodular and peribronchial branched. Peripheral cancer may develop in the form of round tumor, pneumonia-like tumour, or a tumour at the very top of the lung (Pancoast).
TNM classification of lung cancer and the stages of the process are provided in detail in the article “Malignant tumors of the lung.”
3The symptoms of lung cancer
Lung cancer clinical picture is similar to other manifestations of malignant lung tumors. Typical symptoms are persistent cough with muco-purulent sputum, shortness of breath, low-grade body temperature, chest pain, hemoptysis. Some differences in the clinical picture of lung cancer are caused by the anatomical location of the tumor.
The cancer is localized in the large bronchi developing early clinical symptoms due to irritation of the bronchial mucosa, causing misbalance of its permeability and ventilation of the corresponding segment, lobe or an entire lung.
The involvement of the pleura and the nerve trunks causes pain, cancerous pleurisy and disturbance in the innervation zones of the relevant nerves (phrenic, vagus or recurrent). Metastasis of lung cancer to distant organs causes secondary symptoms from side of the affected organs.
Malignant invasion of the bronchi causes bronchial cough with phlegm often mixed with blood. Hypoventilation and atelectasis of a segment or lobe of the lung leads to cancer-like pneumonia attenuated by increased body temperature, purulent sputum and shortness of breath. Cancer pneumonia responds well to anti-inflammatory therapy, but recurs again. Cancer pneumonia is often accompanied by hemorrhagic pleurisy.
If the tumor invades or compresses the vagus nerve, it causes paralysis of the vocal muscles and leads to hoarseness of the voice. The affection of the phrenic nerve leads to paralysis of the diaphragm. Invasion of cancer in the pericardium causes pain in the heart and leads to pericarditis.
The invovement of the superior vena cava leads to disruption of the venous and lymphatic drainage of the upper body. So-called superior vena cava syndrome is manifested by facial swelling, flushing with cyanotic tinge, swelling of the veins in the arms, neck, chest, and shortness of breath, in severe cases – headache, visual disturbances, and impaired consciousness.
Peripheral lung cancer
Peripheral lung cancer at an early stage of development is asymptomatic, since there are no pain receptors in the lung tissue. As the tumor grows it invades the bronchi, the pleura and the neighboring organs. Local symptoms of peripheral lung cancer include cough with blood-streaked sputum and superior vena cava compression syndrome, hoarseness of the voice. The invasion of pleura is accompanied by cancer pleurisy and compression of the lung due to pleural effusion.
The development of lung cancer is accompanied by an increase of general symptoms: intoxication, shortness of breath, weakness, weight loss, fever.
Advanced lung cancer is accompanied by complications in the organs to which the cancer has spread, the disintegration of the primary tumor, the phenomenon of bronchial obstruction, atelectasis and profuse pulmonary hemorrhage. The most common causes of death are extensive metastases, pneumonia, pleurisy and cachexia (severe exhaustion of the body).
4Lung Cancer Diagnosis
Diagnosis of suspected lung cancer includes:
- general blood and urine tests;
- biochemical blood parameters analysis;
- sputum cytology, bronchial wahsing;
- physical data evaluation;
- X-rays of the lungs in 2 projections, linear tomography, CT scan of the lungs;
- bronchoscopy (fibrobronchoscopy);
- pleural puncture (in the presence of effusion);
- diagnostic thoracotomy;
- prescalenic biopsy of the lymph nodes;
- Other diagnostic procedures
More information about diagnostic methods for lung cancer is available here.
55Lung Cancer Treatment
The leading method in lung cancer treatment is surgery in combination with radiation therapy and chemotherapy. The operation is performed by thoracic surgeons.
In case there are contraindications or the previous methods happened to be ineffective, the palliative treatment is carried out. It is aimed to relieve the state of a terminally ill patient. Palliative treatments include pain relief, oxygen therapy, detoxification, palliative surgery: tracheostomy, gastrostomy, enterostomy, nephrostomy, etc.).
Pneumonia cancer requires anti-inflammatory treatment, cancer pleurisy – thoracostomy; in case of pulmonary hemorrhage haemostatic therapy is required.
6Prediction and prevention of lung cancer
The worst prediction is statistically observed when lung cancer stays untreated: nearly 90% of patients die within 1-2 years after diagnosis. In case of non-combined surgical treatment of lung cancer the five-year survival rate is about 30%. Treating lung cancer during the first stage shows the five-year survival rate of 80%, at the second stage – 45%, and the third – 20%.
Radiotherapy or chemotherapy shows 10% for the five-year period survival of patients with lung cancer; the combined treatment (surgery + chemotherapy + radiotherapy) shows the 40 % survival rate for the same period. Metastasis of lung cancer to the lymph nodes and distant organs influences the prognosis in a negative way.
The issues on prevention of lung cancer are important due to the high rate of mortality from this disease. The most important element in the prevention of lung cancer lies in the educative activities, prevention of the development of inflammatory and destructive lung diseases, detection and treatment of lung benign tumors, smoking cessation, elimination of occupational hazards and everyday exposure to carcinogenic factors.
Getting a chest X-ray at least once in 2 years can detect lung cancer at an early stage and prevent the development of complications associated with advanced forms of cancer.