1.Smoking Paper cigarette contains more than 40 kinds of carcinogenic substances, and a large number of epidemiological studies have proved that the relationship between smoking and lung cancer is extremely close, and smoking makes the incidence and mortality of lung cancer continue to rise. Among the patients who die of lung cancer, more than 80% are caused by smoking, including passive smoking, and the mortality rate of lung cancer in male smokers is 8-20 times higher than that of non-smokers. At the same time, there are data confirming that if one smokes 25 cigarettes per day for more than 20 years, the incidence of lung cancer is 2.27 per 1,000; if one smokes 15-24 cigarettes per day, it may be reduced to 1.39 per 1,000; if one to 14 cigarettes per day, it is as low as 0.75 per 1,000. Women passive smokers are also prone to lung cancer, and the current increase in female passive smokers has increased their lung cancer risk. There are even data showing that the risk of lung cancer in women due to passive smoking is three times higher than that of male direct smokers. The epidemiological changes in lung cancer worldwide are related to the prevalence of cigarettes in specific countries. Although the number of smokers has peaked and tended to decline in developed countries such as the United States, China, as well as other developing countries, has held an upward trend over the past 20 years. The results of the Chinese population smoking rate survey show that in 2002 the smoking rate in China was 66.0% for men and 3.08% for women, compared with the results of the 1996 survey, although the total smoking rate decreased by 1.8%, but the smoking rate of people aged 15 to 24 years old is increasing, and the passive smoking rate is 52.l%. It is predicted that if the increase in smoking rate among young people and the spread of smoking behavior among the population cannot be effectively controlled, the incidence level of lung cancer among Chinese residents will continue to rise in the near future.
2.Dietary and nutritional factors The research results on the relationship between alcohol consumption and the risk of lung cancer are not consistent. However, most scholars believe that alcohol consumption is a risk factor for lung cancer, and acetaldehyde, the first metabolite of alcohol, is believed to be related to lung cancer. Dietary phytoestrogens have estrogen-like effects and have been shown to have chemopreventive effects on lung cancer in in vitro studies. A study from the United States confirmed that high dietary intake of phytoestrogens reduces the risk of lung cancer, comparing self-reported dietary intake of 12 phytoestrogens in 1526 lung cancer cases and 1483 healthy controls, and found that in lung cancer patients, intake of 10 of the 12 estrogens was significantly lower than in healthy controls. Another study from the Czech Republic also confirmed the effect of dietary factors on lung cancer, finding that for women who smoked, dietary intake of milk or dairy products, vegetables, and exercise reduced the risk of lung cancer; for non-smoking women, drinking more black tea had a significant protective effect. There is also information showing that regular intake of fresh vegetables and fruits can also reduce the incidence of lung cancer.
3.Environmental factors Atmospheric and environmental pollution is another risk factor for lung cancer. A foreign study confirmed that serious air pollution can lead to high incidence of lung cancer, and the incidence of lung cancer is significantly higher in cities than in villages, with the incidence rates of 4%-9% and 1%-3% respectively. The incidence of lung cancer is significantly higher in cities than in the countryside, with incidence rates of 4-9% and 1-3%, respectively. In addition to air pollution, the fuel and fumes used in cooking are also risk factors for the development of lung cancer in women, and the combustion products of fuel contain a variety of carcinogenic substances. Indian women spend an average of 4-6 hours a day on cooking, and a study from India confirmed a definite correlation between exposure to cooking fuels and lung cancer, and the cooking index (average daily cooking time multiplied by years of cooking) was significantly higher in lung cancer patients than in healthy controls, leading to the conclusion that cooking is an important risk factor for lung cancer in non-smoking women, and that cooking should be done in a well-ventilated kitchen.
The relationship between certain occupational exposures and lung cancer is relatively clear, and more than ten industrial toxicants or occupational processes have been identified as related to lung cancer. For example, the incidence and mortality rate of lung cancer among miners of Yunnan Jielao Yunxi Company is the highest in the world, with the incidence and mortality rate of lung cancer among male miners being as high as 1180.3/100,000 and 729.6/100,000, respectively. Through the research on the working environment of tin mines, it is found that radon gas and arsenic-containing dust in the working environment are important factors for the high incidence of lung cancer among miners. In addition, lung cancer can be induced by large amount of inhalation of radioactive substances such as uranium and radium, long-term exposure to metal minerals containing radioactivity and microwave radiation. In addition, occupational exposure to silica, inorganic arsenic, asbestos, chromium, nickel, coal tar, mustard gas, dichloromethyl ether, etc., can increase the risk of lung cancer.
Psychosocial and genetic factors Young people are prone to mental depression and depression due to the pressure of work, family, life and other aspects, which, together with unhealthy lifestyle, can bring “pollution” to the body and mind and lead to the decline of immune function and induce diseases. In addition, genetic factors play a role in the process of tumor development. If there is a history of tumor in the family, it is also a risk group for developing lung cancer.
6.Pre-clinical signs After suffering from lung cancer, the body will usually show some signs, mainly including
(1) Cough, a common early symptom, about 2/3 of patients have this symptom, which can be mild dry cough or severe cough, mostly persistent. Patients with chronic cough may have a change in the nature of the cough, such as the cough becoming more frequent or an irritating dry cough, which is often not easily noticed by patients.
(2) Bloody sputum, mostly blood sputum or blood in sputum, can cause hemoptysis if it erodes large blood vessels.
(3) Chest pain, early chest pain is mild, manifested as intermittent non-severe dull or drilling pain, the location is not certain, and the relationship with breathing is not certain.
(4) Fever, unexplained fever, poorly treated with antibiotic medication.
(5) Dyspnea with progressive worsening.
(6) Unexplained chest tightness and shortness of breath.
(7) Non-specific systemic symptoms, such as loss of appetite and weight loss.
(8) Pulmonary hypertrophic osteoarthropathy, mainly manifested as painful large joints of bones, pestle-like fingers and toes, i.e., hyperplasia, hypertrophy and pestle-like expansion of the ends of fingers or toes.
(9) Carcinoid syndrome, the main clinical manifestations of which are abdominal pain and diarrhea, facial flushing, bronchospasm, etc.
(10) Gynecomastia, the main clinical manifestations are bilateral or unilateral mammary gland development in men.
(11) Superior vena cava compression syndrome, manifesting as edema of the head and neck and even upper limbs, angry veins in the neck and upper chest, capillary dilation, etc.
(12) Horner’s syndrome, manifested by sunken eyes on the affected side, ptosis of the upper eyelid, smaller eye fissures, reduced pupils, and absence of sweating on the affected side.
(13) Pancoast syndrome, which further presents with upper limb pain on top of Horner syndrome.
(14) Other common symptoms of tumor invasion and metastasis include: hoarseness caused by tumor involving the recurrent laryngeal nerve; headache, vomiting and hemiparesis caused by brain metastasis; persistent bone pain at corresponding sites caused by bone metastasis. When these symptoms occur, especially for people over 40 years old and long-term and heavy smokers, they should consider the possibility of lung cancer and go to hospital for comprehensive examination in time.