How Does Smoking Increase the Risk of Lung Cancer?

The lungs are the main component of the human respiratory system. They are important organs for inhaling oxygen, expelling carbon dioxide, and maintaining normal human metabolism.

The lungs are located on both sides of the heart in the chest cavity and are divided into the left lung and the right lung. The left lung is divided into two lobes, the upper and lower lobes, and the right lung is divided into three lobes, the upper, middle and lower lobes. The lungs have a soft, spongy structure, and can contract and relax with breathing. Each lobe is connected to the trachea by a tube called a bronchus.

With continuous differentiation, the bronchi gradually become thinner. We call them bronchi, bronchioles, terminal bronchioles, respiratory bronchioles and alveolar ducts, etc. The branches at the end of the bronchi are sac-shaped and are called alveoli.

How "close" are you to lung cancer if you smoke?

There are nearly 300 million alveoli in our lungs. The alveolar ducts and alveoli are surrounded by capillaries. The alveoli are the place where the human body exchanges oxygen and carbon dioxide with the outside world. Oxygen is absorbed by the blood through the alveolar wall and transported to various parts of the body. Carbon dioxide and other waste gases produced by the human body enter the alveoli through the alveolar wall from the blood and are finally expelled from the body with breathing.

The total area of ​​adult alveoli is 80 to 100 square meters. Usually, some alveoli are closed. During intense activities, all alveoli participate in gas exchange.

The lungs of normal people are ruddy, but smokers have a lot of tar and smoke toxins in their bodies, and their lungs show different colors, which we call "colorful lungs". As the smoking time increases, the color of the lungs gradually deepens, and even if you stop smoking, the color of the lungs will not recover.

Lung cancer refers to cancer originating from the bronchial epithelium or alveolar epithelium, which is medically called primary bronchial lung cancer.

Lung cancer is the most common malignant tumor in the lungs. Under the influence of various carcinogenic factors, bronchial epithelial cells or alveolar epithelial cells in the lung tissues are transformed into cancer cells. Cancer cells grow and multiply uncontrollably, and their volume gradually increases to form solid tumors.

According to the location of occurrence, lung cancer is divided into central lung cancer and peripheral lung cancer. Most of the former occurs in the trachea, left and right common bronchi, lobar bronchi and segmental bronchial cavities, and grows to the surrounding lung tissues; peripheral lung cancer occurs in alveolar tissues and spreads to other parts along the walls of bronchioles and lung tissues.

In addition to continuous infiltration and growth in the lungs, cancer cells can also enter lymphatic vessels and metastasize to lymph nodes; enter capillaries and metastasize to various parts of the body with blood circulation, such as the liver, bones, and brain.

Lung cancer is now the malignant tumor with the fastest increasing incidence in my country.

In 2004, 71 people out of 100,000 Beijingers suffered from lung cancer, while 8 years ago, 49 people out of 100,000 Beijingers suffered from lung cancer. In other words, the incidence of lung cancer in Beijing has nearly doubled in 8 years.

The mortality rate of lung cancer is also far ahead of other malignant tumors. One in every four male malignant tumor patients is a lung cancer patient, and one in every five female malignant tumor patients is a lung cancer patient. In the past 30 years, the mortality rate of lung cancer in my country has increased nearly fivefold.

The increasing number of smokers in my country is considered to be the main reason for the high incidence and mortality of lung cancer.

Statistics show that the smoking rate of adult males in Beijing is 58.6%, and that of females is 5.7%. If the current smoking situation in China remains unchanged, then by 2050, nearly 100 million men under the age of 29 will die from smoking in middle age or old age; the number of female deaths will also reach millions.

In recent years, there has been an increasing trend of smoking among teenagers. As long as tobacco production and sales are legal, there will be people smoking, and non-toxic cigarettes do not exist.

Smoking has been recognized as the leading cause of lung cancer.

And it has been proven that it has an additive relationship with the age of starting smoking, the number of years of smoking, the number of cigarettes smoked per day, and the type of cigarettes. The probability of long-term heavy smokers suffering from lung cancer is 10 to 20 times that of non-smokers. The younger the age at which people start smoking, the higher the incidence of lung cancer. A person who smokes 15 to 20 cigarettes a day is 14 times more likely to develop lung cancer than a non-smoker.

In my country, smoking is the main risk factor for male lung cancer. The increase in cigarette consumption is an important reason for the rising trend of male lung cancer. The rapid increase in lung cancer incidence may reflect the rapid increase in cigarette consumption in my country after the 1970s.

According to statistics, my country's per capita cigarette consumption ranks first in the world, and it is one of the only six countries in the world where per capita cigarette consumption continues to rise. If this trend continues, the increase in the incidence of lung cancer will continue until after 2030, by which time my country may become the country with the highest incidence of lung cancer in the world.

In my country, the relationship between female lung cancer and smoking is not as close as that between male and smoking. Smoking can only explain 24% to 35% of the causes of lung cancer. It has been confirmed that the occurrence of female squamous cell lung cancer and small cell lung cancer is closely related to smoking, but the relationship between female lung adenocarcinoma and smoking is weaker.

In recent years, with the increase in the incidence of lung cancer in women, especially lung adenocarcinoma, it may indicate that the characteristics of environmental risk factors have changed, such as outdoor air pollution and environmental pollution factors, or related to low-tar cigarettes, "second-hand smoke", "third-hand smoke", kitchen fumes, house decoration materials and other indoor air pollution and micro-environmental pollution.

Smokers who are prone to lung cancer are related to the following factors:

(1) Smoking age of more than 20 years.

(2) Start smoking before the age of 20.

(3) Smoking more than 20 cigarettes a day.

(4) Quit smoking less than 15 years ago.

(5) The amount of smoke inhaled per puff is large, and most of it is inhaled into the lungs (lung smokers).

(6) Total smoking = (number of cigarettes smoked per day × number of years of smoking) / 20, which takes into account the impact of daily smoking and smoking duration on lung cancer. Total smoking is more than 20 cigarettes per year.

(7) Chronic bronchitis and long-term smoking.

(8) Long-term exposure to indoor "second-hand smoke" environment.

The harm of smoking to lung cancer among teenagers will only be manifested after several years. Studies have confirmed that the lung tissue of adolescents in the growth period is more sensitive to carcinogens, and the risk of lung cancer in the future is greater.