In recent years, the incidence rate and mortality rate of malignant tumors are still rising rapidly with the intensification of population growth and population aging process, the acceleration of modernization such as urban industrialization, environmental pollution and people’s poor lifestyle, etc. According to the epidemiological survey of the Ministry of Health, the mortality rates of lung cancer, liver cancer, colorectal cancer, female breast cancer, bladder cancer and their composition ratios related to the environment and lifestyle are on the rise, among which, the incidence of lung cancer in cities with developed industries is the most obvious.
At present, the mortality rate of lung cancer occupies the 1st place in cancer mortality, and has become one of the most common malignant tumors worldwide that seriously endangers human health.
Its incidence rate has been increasing year by year, and the incidence rate in China has jumped from the 6th place to the 2nd place among the original malignant tumors; it is the 1st place in the mortality rate of urban malignant tumors. The World Health Organization expects that by 2025, the incidence of lung cancer, which is the leading cause of death from malignant tumors in China, will double and become one of the common diseases, and 1 million people will die from lung cancer every year. It is evident that lung cancer has a significant impact on human health. Although lung cancer has a high incidence rate and high mortality rate, the overall 5-year survival rate of lung cancer is only 14.1%, but the 5-year survival rate of stage I lung cancer patients is 60% after surgery, and the 5-year survival rate of stage 0 lung cancer patients can be more than 90%, but through early diagnosis and treatment, the survival period can be extended and good treatment effect can be achieved. The incidence rate of lung cancer can be greatly reduced by quitting smoking, improving lifestyle habits and eating properly.
I. Causal factors of lung cancer
1.Tobacco hazard.
Smoking is the main cause of lung cancer. Paper cigarette contains benzo(a)pyrene and other carcinogenic substances, and long-term smoking can lead to bronchial mucous membrane epithelial cell proliferation and induce lung cancer. A large number of surveys have shown that the risk of lung cancer in smokers increases with the number, duration and type of cigarettes smoked. The incidence of lung cancer in smokers is 10 times higher than that of nonsmokers, and the incidence of lung cancer in heavy smokers is 20 times higher than that of nonsmokers. Among the clinically diagnosed lung cancer cases, those who smoked more than 20 paper cigarettes per day for more than 30 years accounted for more than 80%. In recent years, the danger of “second-hand smoke” has attracted attention.
2.Environmental pollution.
Industrial development of exhaust gas, automobile exhaust, asphalt highway volatiles, etc., which also contains many hydrocarbon carcinogens. The incidence of lung cancer is high in industrialized cities and higher in urban than rural areas.
3.Occupational exposure.
Long-term exposure to radioactive substances such as uranium radium and its derivatives, carcinogenic hydrocarbons, arsenic chromium nickel and other metals, coal tar, asphalt petroleum, asbestos, mustard gas and other substances can induce lung cancer.
4.Chronic lung diseases.
Patients with tuberculosis, silicosis, pneumoconiosis and other underlying diseases have higher incidence of lung cancer than normal people because chronic inflammation and lung fiber scars occur in lung bronchus under the stimulation of long-term chronic adverse substances, and the lesions may cause squamous epithelial chemosis or hyperplasia in the healing process on the basis of which some cases may develop into cancer.
5.Intrinsic factors in human body.
Such as family genetic inheritance and endocrine dysfunction with lowered immune function may also play a role in promoting the development of lung cancer.
The susceptible groups of lung cancer
1. Smokers: Smokers inhale and exhale smoke containing a large amount of carcinogenic substances. Active smoking and passive smoking are equally dangerous, therefore, long-term smokers and those who work and live in the smoke around smokers for a long time are all high-risk groups for lung cancer, especially those with high-risk factors: (male age ≥ 45 years and smoking index > 400 cigarettes/year).
2 . People with occupational exposure: those who are exposed to carcinogenic substances such as radon gas, radioactive substances, asphalt, arsenic, chromium, coal tar, asbestos, etc. in their daily work.
3. People living in polluted environment: people living in areas and cities with heavy air and water pollution.
4.People with chronic lung diseases such as tuberculosis, silicosis and pneumoconiosis.
Early diagnosis of lung cancer
1. Pay attention to the early clinical manifestations of lung cancer
Lung cancer patients, especially early stage patients, are often asymptomatic and only have symptoms common to general respiratory diseases, which often lead to misdiagnosis and delayed diagnosis for most patients due to atypical and non-specific symptoms. Therefore, susceptible people, especially those with high-risk factors, should pay attention to the following early symptoms of lung cancer for early diagnosis of lung cancer.
(1) Cough: Lung cancer usually produces irritating cough because it grows on bronchopulmonary tissues, resulting in respiratory irritation symptoms. Age above 45 years old, especially unexplained frequent irritating dry cough; with tuberculosis and chronic bronchitis and change in the regularity of the original cough.
(2) Hemoptysis: there will be a small amount of bleeding when tumor inflammation causes tissue necrosis and capillary breakage, often mixed with sputum, showing intermittent blood in sputum, hemoptysis, hemoptysis; about 30%-50%.
(3) Chest pain: intermittent chest pain of uncertain location and uncertain relationship with breathing; accounting for 30%-60%.
(4) Chest tightness and shortness of breath: sudden progressive shortness of breath, chest tightness, chest X-ray with pleural effusion.
(5) Chest X-ray shows “inflammation of the lung”, which cannot be completely controlled by treatment, and the symptoms appear repeatedly or worsen.
(6) Symptoms caused by tumor metastasis: such as enlarged lymph nodes in the neck, hoarseness, pleural effusion, bone pain, etc.
(7) Fever: caused by obstruction of bronchus by tumor leading to obstructive pneumonia or cancerous fever, mostly low fever, which may improve after treatment, but often recurring.
(8) Extra-pulmonary symptoms: such as unexplained joint and muscle intractable pain, gynecomastia, etc.
In summary, it is important to raise the alertness to these symptoms, especially the susceptible people should go to the hospital in time once they have similar conditions. Early diagnosis of lung cancer plays an important role in treatment effect and prognosis.
2.Clinical examination.
Clinical screening of lung cancer has started in 1950s, from X-ray light, sputum exfoliative cytology, to bronchoscopy, etc. There are not yet recognized screening means, but early diagnosis of lung cancer can be made clinically from the following aspects.
(1) For high-risk groups, annual chest fluoroscopy or radiographic physical examination is recommended, and spiral CT scan should be performed when masses or shadows are found.
(2) For those with cough, sputum and blood in sputum, repeated sputum examination for cancer cells and/or bronchoscopy should be performed.
(3) Those with lung nodules or shadows found in chest X-ray but negative bronchoscopy can undergo CT localized puncture biopsy.
3.New technologies are applied in the clinic to improve the early diagnosis rate of lung cancer.
(1) Spiral CT and low-dose spiral CT: It can accurately detect lesions smaller than 2-3mm, especially for small nodular lesions with a diameter of 15mm, which is significantly better than X-ray chest radiography. Compared with surgery, the sensitivity of low-dose spiral CT to detect intra-pulmonary nodules ≤6mm is 60% and 95% for those >6mm, but for neoplastic lesions ≥6mm, the sensitivity reaches 100%. A multicenter International Early Lung Cancer Action Plan (I-ELCAP) study showed that 80% of lung cancers picked up by annual low-dose spiral CT were early-stage lung cancers (treatable lung cancers); therefore, it can be used for the diagnosis of early-stage lung cancers and curable-stage lung cancers, which is expected to improve the cure rate and prognosis.
(2) Fluorescence bronchoscopy: Using laser-induced autofluorescence technology, early-stage lung cancer shows fluorescence different from normal tissue for early diagnosis, and the site of early invasive cancer can be identified, making it possible to increase the sensitivity of diagnosing precancerous lung lesions and carcinoma in situ by 1,5-6,3 times.
(3) Sputum exfoliative cytology based on liquid-based cytology technique: This method has improved the methods of sampling, cell separation smear, background influence and cell structure observation. It has greatly improved the detection rate and accuracy of cancer cells, and the diagnosis rate of lung cancer, especially central lung cancer, is significantly higher than that of the traditional smear method.
(4) Breathing gas detection: It was found that there are several alkanes and benzene derivatives in the breathing gas of lung cancer patients that are different from those of normal people, and the detection of these components by spectral analysis instruments can detect early lung cancer and correctly predict 71,1% of lung cancer patients and 66,7% of non-lung cancer patients.
(5) Gene chip and tumor marker detection: with the advantages of large amount of detection information, high accuracy, fast examination speed and high degree of automation, it can make accurate diagnosis without clinical symptoms.
Treatment of lung cancer
The treatment of lung cancer is a comprehensive treatment mainly based on surgery. As long as the stage of lung cancer is in stage II and part of stage IIIa and there is no definite contraindication, surgical resection should be considered.
The 5-year survival rate of stage I lung cancer patients after surgery is 60%, and the 5-year survival rate of stage 0 can be over 90%. The earlier the lung cancer is, the better the treatment effect is. In recent years, significant progress has been made in the comprehensive treatment of lung cancer, which has greatly improved the survival rate of lung cancer. For example, advances in lung cancer chemotherapy and clinical application of targeted drugs, three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and neoadjuvant chemotherapy, surgery, and integrated radiotherapy have significantly improved the survival period and survival quality of lung cancer patients. Immunotherapy and Chinese medicine play an important role in reducing patients’ response to radiotherapy and chemotherapy, improving the immunity of the body, consolidating the therapeutic effect and promoting and restoring the function of the body.
V. Prevention of lung cancer
Lung cancer prevention is more important than treatment, because it is closely related to environment, smoking and bad living habits, so lung cancer can be prevented through the following aspects
1. Quit smoking: It is never too late for smokers to quit smoking, but the earlier the better! Quitting smoking makes the risk of lung cancer significantly lower, and the incidence of lung cancer starts to decrease after 5 to 10 years of quitting, and after fifteen years of stopping smoking, the chance of getting lung cancer is the same as that of non-smokers.
2.Stay away from occupational exposure
3.Healthy lifestyle habits: eat a reasonable diet, more vitamin-rich vegetables and fruits, coarse cereals. Eat less smoked food and no moldy food.
5.Pay attention to environmental and living hygiene: reduce harmful compounds during and after house decoration; pay attention to pollution in the kitchen and strengthen kitchen ventilation.
6.Participate in regular physical exercise and frequent outdoor activities.
7.Positive life attitude: cultivate an optimistic and open-minded personality and life attitude.
Although lung cancer is a malignant tumor, it can be prevented through active measures such as quitting smoking. In addition, the combination of focusing on early symptoms and choosing appropriate clinical examination means can diagnose lung cancer at an early stage and select treatment at an early stage, which can achieve good treatment effect.