Primary bronchopulmonary cancer (lung cancer for short) is a cancer that originates in the bronchial mucosa and alveoli, and is one of the common malignant cancers. The occurrence of this disease is mainly affected by chemical carcinogens, smoking is one of the main reasons. In addition, industrial waste gas and air pollution, which produce a lot of polycyclic aromatic hydrocarbons and other harmful gases, can also induce lung cancer. Most lung cancers occur between the ages of 35/75. There are more men than women.
I. Classified by the site of tumor occurrence.
(1) Central type tumors occur in bronchi above the segment, that is, in lobar bronchi and segmental bronchi.
(2) Peripheral tumors occur in bronchi below the segment.
(3)Diffuse tumor occurs in fine bronchi or alveoli and is diffusely distributed in both lungs.
II. Histopathological typing.
(1) Squamous cell carcinoma referred to as squamous carcinoma, including spindle cell (squamous) carcinoma.
(2) Adenocarcinoma includes adenoid ductal adenocarcinoma, papillary adenocarcinoma, fine bronchial lung cancer, and alveolar cell carcinoma.
(3) Adenosquamous carcinoma.
(4) Undifferentiated carcinoma is divided into small cell carcinoma (including oat cell type, intermediate cell type, and compound oat cell type) and large cell carcinoma (including giant cell carcinoma and clear cell carcinoma).
(5) Carcinoid tumors (endocrine tumors of the lung).
(6) Bronchial adenocarcinoma including adenoid cystic carcinoma, mucinous epidermoid carcinoma, and adenoid follicular cell carcinoma.
III. Typing by clinical features.
Since the biological behavior of small cell lung cancer is significantly different from other epithelial carcinomas (squamous carcinoma, adenocarcinoma, adenosquamous carcinoma, and large cell carcinoma), i.e., it is clinically highly malignant, has extensive distant metastasis at early stage, and is more sensitive to chemotherapy and radiotherapy, thus the treatment principles are different from other epithelial carcinomas. Therefore, from the clinical perspective, the world currently tends to roughly classify these two types of lung cancer with different biological behaviors into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), which includes epithelial cancers other than small cell carcinoma.
The following is a brief description of the common symptoms and diagnostic points of lung cancer.
I. Symptoms
Cough is the most common early symptom of lung cancer. A dry cough with no sputum or a small amount of white foamy sputum is caused by stimulation of bronchial mucosa by the mass.
Hemoptysis and hematemesis are also one of the first symptoms of lung cancer. Although their incidence is lower than that of cough, their diagnostic significance is more important than that of cough. It is often more blood than sputum and bright red in color, and sometimes it is not easy to control. When the cancer erodes blood vessels, it may cause hemoptysis.
Chest pain: When the tumor is located near the pleura, it is easy to produce irregular pure pain; when the ribs and spine are invaded, there may be continuous chest pain and fixed pressure pain; when the tumor compresses the intercostal nerve, the chest pain is in the area where the nerve travels; when the mediastinal lymph nodes are involved, there may be deep posterior sternal pain. This is due to the metastasis of mediastinal lymph nodes in undifferentiated cancer.
Fever: There are two types of fever caused by lung cancer, one is inflammatory fever caused by bronchial obstruction or wall compression; the other is the so-called “cancer fever”, which is caused by toxins from tumor necrosis, and often occurs after extensive metastasis at a later stage.
Chest tightness and shortness of breath: shortness of breath caused by bronchial stenosis and obstruction. Concurrent pleural effusion, cancerous lymphangitis and diaphragmatic paralysis by tumor compression of phrenic nerve may also cause shortness of breath.
V. Late stage symptoms of lung cancer
The thoracic cavity is a very complicated space, three-fourths of the lung surface is surrounded by the chest wall, which is composed of a thin layer of lining (wall pleura), fat, muscle, ribs and skin in different proportions. Tumor invasion of any of these parts can cause pain. Thus, most patients with intra-thoracic regional dissemination of lung cancer have symptoms of chest pain.
The area that surrounds the apex of the lung – the tip of the lung – forms a special area of the chest wall. Nerve fibers from the neck, sensory and motor innervation of the upper extremities enter the upper extremities through this area. As a result, if a tumor invades this area, one will often feel pain and weakness in the affected upper limb. As a type of lung cancer, this so-called “Pancoast cancer”, or upper sulcus cancer, often has shoulder pain as the main symptom. This pain often requires analgesics to be relieved. Often these patients are easily referred to an orthopedic surgeon or neurologist, thus losing the opportunity for early diagnosis. Nearly a quarter of the lung surface is adjacent to the so-called “mediastinum”. The word “mediastinum” means “the middle part of the chest, the division” and it represents a space containing a series of vital organs. The mediastinum is located directly behind the sternum and is considered to be “central” in the layman’s world. The trachea and main bronchus pass through the mediastinum. The esophagus passes immediately posterior to the trachea and descends through it. The heart and its large blood vessels, as well as some of the major life-related nerves, also pass through this area. If cancer invades the mediastinum, the following symptoms may occur.
Hoarseness is the most common symptom. The recurrent laryngeal nerve, which controls the left side of the articulatory function, travels from the neck down to the chest and returns up to the larynx around the large vessels of the heart, thus innervating the left side of the articulatory organ. Therefore, if the tumor invades the left side of the mediastinum and compresses the recurrent laryngeal nerve, hoarseness will be produced without other symptoms of sore throat and upper respiratory tract infection.
On the right side of mediastinum, there is superior vena cava, which transmits venous blood from the upper limbs and head and neck back to the heart. If the tumor invades the right side of the mediastinum and compresses the superior vena cava, it will initially cause anger in the jugular vein due to poor reflux and eventually lead to facial and neck edema, which requires prompt diagnosis and management.
Ultimately, patients with regional spread of lung cancer almost always have varying degrees of shortness of breath. Normal tissue fluid produced by the lungs and heart muscle is returned by the lymph nodes in the median thorax. If these lymph nodes are obstructed by the tumor, this tissue fluid will accumulate in the pericardium to form a pericardial effusion or in the thorax to form a pleural effusion. Both of these conditions can lead to shortness of breath. However, the combination of chronic lung disease of varying degrees in many smoking patients makes the identification of shortness of breath difficult. In addition, the loss of respiratory function due to the growth of tumor in part of the lung tissue can cause respiratory discomfort due to impaired positive respiratory function, which is initially felt only during exercise and eventually even at rest. All the above symptoms indicate that lung cancer is in the progressive stage.
VI. Examination methods.
1. Imaging examination
X-ray examination∶Description of central type lung cancer: It is generated in the bronchial cavity in the early stage and appears as an increase in the density of hilar shadow. When it invades the bronchial wall and grows outward, a hilar mass appears, and description of peripheral type lung cancer: It appears as a nodule or spherical lesion with light density and blurred outline in the early stage, which may have shallow lobulation and fine burr.
CT examination: Clinically, a mass less than 1 cm in diameter can be distinguished, with cut marks and burrs on the edges of the mass.
MRI (magnetic resonance imaging): MRI can be used for multiplanar imaging, and the intrapulmonary mass is clearer than CT.
2. Endoscopy
Bronchoscopy: Bronchoscopy plays an important role in the diagnosis of lung cancer, especially for early central lung cancer.
Mediastinoscopy: Mediastinoscopy is an effective means to diagnose mediastinal lymphatic metastasis of lung cancer. Any intrathoracic lesion with mediastinal lymph node enlargement that cannot be diagnosed by other examination methods can be diagnosed by this means.
3. Sputum cytology examination: Primary lung cancer originates from trachea and bronchial epithelium, so tumor cells will be shed in the lumen and excreted with sputum, so sputum cytology examination can be performed to diagnose lung cancer.
VII. Tumor marker test for lung cancer
The tumor marker tests for lung cancer mainly include the following.
Carcinoembryonic antigen (CEA)
CEA is a fetal protein present in adult cancer tissues, CEA was discovered in 1965. It is an acidic glycoprotein that is synthesized in the small intestine, liver, and pancreas during embryonic life and is present in extremely low levels in adult serum (generally <5 mg/L). CEA is a useful indicator for cancer diagnosis, prognosis and recurrence prediction.
Neuron-specific enolase (NSE)
①It can be used as an aid to diagnose and monitor the therapeutic effect of small cell lung cancer. The concentration of NSE gradually decreases to normal when the treatment is effective.
NSE elevation is used to monitor recurrence 4-12 weeks earlier than the clinical determination of recurrence. ②It can be used to monitor changes in neuroblastoma, evaluate the efficacy of treatment and predict recurrence. ③Serum NSE may also be increased in endocrine tumors, such as pheochromocytoma, islet cell tumor, medullary thyroid carcinoma, melanoma, and retinoblastoma.
Squamous cell carcinoma antigen (SCC)
SCC is a marker of squamous epithelial carcinoma, and SCC is elevated in all kinds of squamous carcinomas. The positive rate of lung squamous carcinoma is 46-90%, and the concentration of SCC in serum increases with the aggravation of the disease.
Glycoantigen 125 (CA125)
It can also be elevated in malignant tumors such as lung cancer, ovarian cancer, endometrial cancer, fallopian tube cancer, pancreatic cancer, gastric cancer, breast cancer, esophageal cancer, etc.
Cytokeratin 19 fragment (CyFRA21-1)
CyFRA21-1 is a new marker for lung squamous epithelial cell carcinoma and non-small cell lung cancer. It is significantly elevated in patients with lung squamous epithelial cell carcinoma and has a sensitivity of 70% specificity of 95%. It is important for the early diagnosis of non-small cell lung cancer to observe the efficacy and prognosis.
For general lung cancer tumor marker examination, single or multiple tests can be selected from several indicators, such as CEA, CA125, NSE, SCC, CyFRA21-1, etc., especially if several indicators are combined for better results.