I. Overview of lung cancer
Lung cancer occurs in the bronchial mucosa epithelium and is also called bronchopulmonary cancer. Lung cancer generally refers to cancer of the parenchyma of the lung, and usually does not include other mesodermal tumors of cribriform origin, or other malignant tumors such as carcinoid tumors, malignant lymphomas, or tumors that metastasize from other sources. Therefore, in the following, we refer to lung cancer as malignant tumors derived from bronchial or fine bronchial epidermal cells, which account for 90-95% of malignant tumors of the lung parenchyma.
Lung cancer is currently the number one cause of cancer deaths worldwide, with 600,000 deaths worldwide in 1995, and the number is increasing every year. The incidence of lung cancer in women is especially on the rise. The disease mostly develops at the age of 40 or above, with the peak age of incidence between 60 and 79. The prevalence rate of men and women is 2.3:1, and race, family history and smoking all have an impact on the development of lung cancer.
Lung cancer originating from the bronchial mucosa epithelium confined to the basement membrane is called carcinoma in situ, which can grow into the bronchial lumen or/and adjacent lung tissues and can spread through lymphatic bloodstream or transbronchial metastasis. The growth rate and metastasis of carcinoma are related to the biological characteristics of the carcinoma, such as the histological type and degree of differentiation.
The distribution of lung cancer is more in the right lung than in the left lung, more in the upper lobe than in the lower lobe, and the cancer can occur from the main bronchus to the fine bronchus. Lung cancer originating from the main bronchus and lobe bronchi is called central lung cancer if it is located close to the hilum; lung cancer originating below the bronchi of the lung segment is called peripheral lung cancer if it is located in the peripheral part of the lung.
1.There are two basic types of lung cancer as follows.
(1) small cell lung cancer (SCLC) or oat cell type, to which one third of lung cancer patients belong.
Small cell lung cancer (SCLC) has short tumor cell multiplication time and rapid progression, and is often accompanied by endocrine abnormalities or carcinoid syndrome; since patients develop bloodstream metastasis at an early stage and are sensitive to radiotherapy, treatment of small cell lung cancer should be based on systemic chemotherapy, combined with radiotherapy and surgery as the main treatment means. Combination therapy is the key to successful treatment of small cell lung cancer.
(2) Non-small cell lung cancer (NSCLC) category, one third of lung cancer patients belong to this category. This distinction is important because the treatment options for these two types of lung cancer are very different. Patients with small cell lung cancer are treated primarily with chemotherapy. Surgical treatment does not play a major role in patients with this type of lung cancer. On the other hand, surgical treatment is primarily indicated for patients with non-small cell lung cancer. Another type of cancer is pheochromocytoma.
II. Causes of lung cancer
The etiology of lung cancer is still not completely clear. A lot of information shows that the risk factors of lung cancer include smoking (including second-hand smoke), rock wool, radon, arsenic, ionizing radiation, halogenated alkenes, polycyclic aromatic compounds, nickel and so on. The details are as follows.
1, smoking: long-term smoking can lead to bronchial mucosa epithelial cell hyperplasia phosphoepithelial growth induced squamous epithelial carcinoma or undifferentiated small cell carcinoma non-smokers can also suffer from lung cancer but adenocarcinoma is more common. In addition, paper cigarettes release carcinogenic substances when burning.
2.Atmospheric pollution.
3, occupational factors: long-term exposure to radioactive substances such as uranium radium and its derivatives carcinogenic hydrocarbons arsenic chromium nickel copper tin iron coal tar asphalt petroleum asbestos mustard gas and other substances can induce lung cancer mainly squamous carcinoma and undifferentiated small cell carcinoma.
Chronic lung diseases such as tuberculosis, silicosis and pneumoconiosis can coexist with lung cancer, and the incidence of cancer in these cases is higher than normal people.
5. Intrinsic factors such as family genetics, lowered immune function, metabolic activity, endocrine dysfunction, etc.
Lung cancer symptoms
1.Early symptoms
There are no special symptoms of lung cancer in early stage, but only symptoms common to general respiratory system diseases, such as cough, sputum and blood, low fever, chest pain and tightness, which can be easily ignored. The specific manifestations of common symptoms of lung cancer in early stage are
(1) Cough: Lung cancer usually produces irritating cough because it grows on bronchopulmonary tissues, resulting in respiratory tract irritation.
(2) Low fever: Obstructive lung lobes often exist after the tumor blocks the bronchial tubes, and the degree varies from low fever in mild cases to high fever in severe cases, which may temporarily improve after medication but will recur soon.
(3) Chest distention pain: Early stage of lung cancer has mild chest pain, mainly manifested as boring pain, hidden pain, the location is not certain, and the relationship with breathing is also uncertain. If the pain is persistent, it means that the cancer may involve the pleura.
(4) Sputum blood: When tumor inflammation causes necrosis and capillary breakage, there will be a small amount of bleeding, which is often mixed with sputum and appears intermittently or intermittently. Many patients with lung cancer visit the doctor because of sputum blood.
2.Symptoms of late stage lung cancer
(1) Facial and neck edema: There is superior vena cava on the right side of mediastinum, which transmits venous blood from upper limbs and head and neck back to heart. If the tumor invades the right side of the mediastinum and compresses the superior vena cava, the jugular vein will initially become angry due to poor reflux, and finally it will lead to facial and neck edema, which needs to be diagnosed and treated in time.
(2) Hoarseness is the most common symptom: the recurrent laryngeal nerve, which controls the left side of the articulatory function, travels down from the neck to the chest and returns upward around the large blood vessels of the heart to the larynx, thus innervating the left side of the articulatory organ.
(3) Shortness of breath: Patients with lung cancer that undergoes regional spread 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 middle of the chest. If these lymph nodes are blocked 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 some lung tissues may cause respiratory discomfort due to the impairment of proper respiratory function, which may be felt only during exercise at first, but eventually even at rest.
3.Symptoms of extensive metastatic lung cancer
Because lung cancer is prone to metastasis at an early stage, symptoms related to metastasis are often the first symptoms discovered by doctors or patients. If the lesion metastasizes to the brain, it may produce persistent headache and hazy vision. Continued progression may lead to confusion or even epilepsy. The nature of this headache is not significantly different from a normal tension headache and is therefore highly overlooked. Blurred vision is mainly manifested as difficulty in reading newspapers or watching TV. Because most lung cancer patients are elderly, they often mistakenly believe that they only need to change their glasses, but the key is the change in the nature of their vision. Initially, they are very sensitive to changes in consciousness and vision.
If the cancer metastasizes to bone, it leads to bone destruction and when the destruction reaches a certain level, bone pain ensues. If the outer layer of hard bone cortex is destroyed, the bone structure can become extremely unstable. If it occurs in the ribs, there may be discomfort, but if it occurs in a long, heavily loaded bone such as the femur or humerus, there is a high risk of fracture during daily activities.
Finally, and most problematic, lung cancer has metastasized to the spine. In most patients, metastases to the spine can cause pain. The problem, however, is that the cancer can metastasize further into the spinal cord. This will first manifest as back pain and then spread to the lower extremities, where there may be weakness in the lower extremities, incontinence, and eventually paralysis below the point of metastasis. Therefore, the presence of back pain in heavy smokers should also be taken seriously.
However, the most common symptoms of distant metastases or systemic metastases are weakness and wasting. Patients with distant metastases have unexplained weight loss, which often occurs before the loss of appetite and does not help even if the appetite is increased.
4. Physical signs
(1) Restricted croup is a limited croup, which mostly appears in the inspiratory phase and does not disappear after coughing.
(2) Hoarseness appears when lymph node metastasis compresses or invades the recurrent laryngeal nerve.
(3) superior vena cava syndrome when the tumor compresses or invades the superior vena cava, the venous return is blocked, producing edema of the head, face, neck and upper limbs, varicose veins and edema in the upper chest, accompanied by dizziness, chest tightness, shortness of breath and other symptoms.
(4) Horner’s syndrome when pulmonary apical carcinoma compresses or invades the cervical sympathetic ganglion, producing sunken eyes on the affected side, ptosis, narrowed pupils, narrowed eye fissures, increased skin temperature of the upper chest on the affected side, and absence of sweating.
(5) Pain in the shoulder and arm When the apical lung cancer compresses or invades the brachial plexus nerve, radiating burning pain in the shoulder and upper extremity on that side appears.
(6) shortness of breath and chest tightness when the phrenic nerve is invaded.
(7) dysphagia caused by enlarged mediastinal lymph nodes compressing the esophagus, and breathing difficulty caused by compression of the trachea.
(8) pericardial invasion, pericardial effusion, shortness of breath, cardiac arrhythmia, cardiac insufficiency, etc., when the pericardium is invaded.
(9) Pleural metastasis can be seen as chest pain, cancerous pleural fluid, etc.
(10) Metastasis of lung cancer is commonly found in bone, liver, brain, kidney, adrenal gland, subcutaneous tissue, etc. In addition, internal metastasis of lung cancer is also more common. The clinical symptoms and signs vary according to the metastatic sites.
(11) Extra-pulmonary signs commonly include joint pain or hypertrophy of extremities, pestle finger, polyneuritis, myasthenia gravis, Cushing’s disease, gynecomastia hypertrophy, hypercalcemia, mental abnormalities, etc.