I. Causal factors of lung cancer
Lung cancer is the most dangerous malignant tumor to human health and life in the world today, and has become the main cause of human death from cancer, accounting for about 30% of all cancer deaths.
(1) Smoking has been recognized as the most important causative factor of lung cancer.
(2) Occupational lung cancer-causing factors.
(3) Environmental pollution such as atmospheric pollution.
(4) Indoor radon pollution.
(5) Other risk factors of lung cancer: such as tuberculosis, pneumonia, chronic bronchitis, emphysema, etc. A certain amount of selenium has inhibitory and preventive effects on cancer.
(6) Under the influence of internal and external factors, multi-gene mutations of oncogenes and oncogenes in human body cause multi-stage cell damage and repair errors, and finally cause cancer. Oncogenes such as ras, myc, Rb and oncogene p53 are known to be related to the occurrence of lung cancer.
Prevention of lung cancer
(1) Eat more apples to prevent lung cancer: eating apples regularly can reduce the risk of lung cancer. The report points out that flavonoids contained in apples are important antioxidants produced through metabolism and are the main reason for reducing the incidence of lung cancer. People who regularly consume foods containing flavonoid compounds, especially apples, have a 46% lower lung cancer rate.
(2) Laugh at life with less worries: Recent studies in China have shown that psychosocial factors of lung cancer patients before the onset of lung cancer are one of the important pathogenic risk factors for the development of lung cancer, therefore, eliminating or minimizing the adverse psychosocial factors is also an important part of lung cancer prevention. For example, to maintain a good and optimistic state of mind; to learn to self-regulate psychologically; to take the initiative to talk to relatives and confidants in case of difficulties, so as to make oneself “happy”; to treat people generously and make good interpersonal relationships; to be “contented and happy” with life; to take the initiative to adapt to the environment. Adapt to it.
(3) Carry out mass lung cancer screening: at least once a year, and in high-risk groups and industrial and mining areas, if conditions allow, once every six months. Lung cancer is also prone to occur on the basis of chronic lung diseases, for example, for patients with chronic bronchitis and tuberculosis, regular sputum exfoliation cell examination and chest X-ray examination can easily detect early lung cancer, and some occult cancer and precancerous lesions may also be detected. III. Symptoms of lung cancer
About 5%-10% of early stage lung cancer patients have no symptoms, which can be found only during X-ray physical examination. 90% of patients have symptoms, but they are not early specific symptoms, which can be broadly classified into four categories.
1.Lung symptoms
①Cough: It is the most common symptom, about 2/3 of patients have this symptom. It can be a mild dry cough or a severe cough with varying amounts of sputum. However, in patients with chronic long-term cough once the nature of the cough changes, or frequency or nocturnal cough occurs, be alert to lung cancer. Persistent and uncontrollable cough is one of the most painful typical symptoms of lung cancer.
②Hemoptysis: half of the lung cancer patients have this symptom. once smoking men over 40 years old have blood in sputum, blood or small blood clots, the possibility of lung cancer is quite high, which is also one of the early symptoms of lung cancer.
③ Chest pain: 30% to 40% of patients have pulmonary chest pain, which is generally intermittent and not severe intra-thoracic pain. It is dull pain or drilling pain, which can last for several minutes to several hours. If the cancer invades the pleura, the pain will be more intense, continuous and fixed.
Fever: Most of the fever in lung cancer is caused by inflammation due to obstruction and poor drainage of bronchial cavity caused by cancer. Early treatment with antibiotics can restore the body temperature to normal, but it is easy to recur. In larger tumors, necrosis occurs in the inflammatory center and often causes higher body temperature due to the absorption of toxins. Sometimes daily flaccid fever for several months, repeated anti-inflammatory treatment is ineffective, once the tumor is removed, the body temperature immediately returns to normal. The fever is often caused by the tumor itself, that is, the so-called “cancer fever”, and the body temperature is often below 38°C. Male smokers over 45 years old who have long-term inflammatory fever in the lungs and have poor treatment results should be especially alert to the possibility of lung cancer.
⑤ Chest tightness and shortness of breath: except for tumor obstruction of bronchus causing pulmonary atelectasis and lung inflammation which can cause chest tightness and shortness of breath, it is usually more obvious in the late stage of lung cancer, especially when there is a lot of pleural fluid.
2. Extra-pulmonary and intrathoracic manifestations: Tumor invasion of pleura, chest wall, mediastinal organs and intrathoracic nerves can cause a series of chest manifestations. Tumor invasion of pleura can cause breathing pain and pleural effusion (i.e. pleural fluid), and bloody pleural fluid indicates poor prognosis. If malignant tumor cells are found in the pleural fluid, the chance of surgery will be lost. The involvement of tumor in mediastinum is mostly caused by mediastinal lymph node metastasis, and few of them are direct invasion. In 5% of patients, tumor compression of superior vena cava causes swelling of upper limbs and above shoulder, venous anger, headache and dyspnea, which indicates advanced stage. Tumor compression on esophagus can cause difficulty in swallowing, and invasion of laryngeal nerve can cause hoarseness.
3.Extra-thoracic metastasis: lung cancer often metastasizes along lymphatic vessels and blood vessels. Nearly 15% of patients have metastases as the earliest manifestation, and hematogenous metastases are most common in adenocarcinoma and small cell lung cancer.
4. Extrathoracic non-metastatic manifestations: Extrathoracic non-metastatic manifestations can occur in only 2% of patients, but the symptoms are complex, involving more systems and the etiology mechanism is unknown. Scleroderma, etc.
5. Systemic manifestations: like other malignant tumors, systemic manifestations of lung cancer may include anorexia, emaciation, weakness, and finally cachexia.