Causes of lung cancer

The cause of lung cancer is still not completely clear, but a large amount of medical data shows that the risk factors for lung cancer include smoking (including secondhand smoke), asbestos, radon, arsenic, ionizing radiation, halogenated olefins, polycyclic aromatic compounds, nickel, etc. The details are as follows:

1. Smoking

Long-term smoking can cause proliferation of bronchial mucosal epithelial cells, induce squamous cell carcinoma or undifferentiated small cell carcinoma. Although non-smokers can also develop lung cancer, adenocarcinoma is more common. Cigarettes release carcinogens when they burn.

2. Air pollution

3. Occupational factors

Long-term exposure to radioactive substances such as uranium and radium and their derivatives, carcinogenic hydrocarbons, arsenic, chromium, nickel, copper, tin, iron, coal tar, pitch, petroleum, asbestos, mustard gas and other substances can induce lung cancer, mainly squamous cell carcinoma and undifferentiated small cell carcinoma.

(IV) Chronic lung diseases such as tuberculosis, silicosis, and pneumoconiosis may coexist with lung cancer. The incidence of cancer in these cases is higher than that in normal people. In addition, chronic inflammation of the lung bronchi and fibrous scar lesions of the lung may cause squamous metaplasia or hyperplasia during the healing process. On this basis, some cases may develop into cancer.

(V) Internal factors of the human body such as family heredity, reduced immune function, metabolic activity, and endocrine dysfunction.

Basic types of lung cancer

1) Small cell lung cancer (SCLC) or oat cell carcinoma

Nearly 20% of lung cancer patients belong to this type; CT image of small cell lung cancer Small cell lung cancer (SCLC) has a short tumor cell doubling time and rapid progression, often accompanied by endocrine abnormalities or carcinoid syndrome; Since patients have hematogenous metastasis in the early stage and are sensitive to radiotherapy and chemotherapy, the treatment of small cell lung cancer should be based on systemic chemotherapy, combined with radiotherapy and surgery as the main treatment methods. Comprehensive treatment is the key to the successful treatment of small cell lung cancer.

2) Non-small cell lung cancer (NSCLC)

About 80% of lung cancer patients belong to this type. This distinction is quite important because the treatment options for these two types of lung cancer are very different. Patients with small cell lung cancer are mainly treated with chemotherapy, and surgery does not play a major role in patients with this type of lung cancer. On the other hand, surgery is mainly suitable for patients with non-small cell lung cancer.

Clinical types of lung cancer

1. Squamous cell carcinoma (also known as squamous cell carcinoma)

It is the most common type of lung cancer, accounting for about 50%. Most patients are over 50 years old, and most are men. Most of them originate from larger bronchi and are often central lung cancers. Although the degree of differentiation of squamous cell carcinoma varies, it generally grows and develops slowly and has a long course. It is more sensitive to radiation and chemotherapy. It first metastasizes through the lymph nodes, and blood metastasis occurs later.

2. Undifferentiated carcinoma

The incidence rate is second only to squamous cell carcinoma. It is more common in men, with a younger age of onset. It usually originates from larger bronchi. Central lung cancer can be divided into several types according to the morphology of tissue cells, such as oat cell, small round cell and large cell, among which oat cell is the most common. Undifferentiated carcinoma is highly malignant, grows fast, and metastasizes to lymph nodes and blood at an early stage. It is more sensitive to radiation and chemotherapy and has the worst prognosis among all types of lung cancer.

3. Adenocarcinoma

Originated from the bronchial mucosal epithelium, a few originate from the mucous glands of large bronchi. The incidence rate is lower than that of squamous cell carcinoma and undifferentiated carcinoma, the age of onset is younger, and it is relatively more common in women. Most adenocarcinomas originate from smaller bronchi and are peripheral lung cancers. There are generally no obvious clinical symptoms in the early stages, and they are often discovered during chest X-ray examinations. They appear as round or oval masses, which generally grow slowly, but sometimes blood metastasis occurs in the early stages. Lymphatic metastasis occurs later.

4. Alveolar cell carcinoma

Originated from the bronchial mucosal epithelium, it is also called bronchioalveolar cell carcinoma or bronchiolar adenocarcinoma. It is located around the lung field and has the lowest incidence among all types of lung cancer. It is more common in women. It is generally highly differentiated and grows slowly. Cancer cells grow along the bronchioalveolar ducts and alveolar walls without invading the alveolar septa. Lymphatic and hematogenous metastasis occur later, but can spread to other lobes through the bronchi or invade the pleura. Alveolar cell carcinoma has two morphological types: nodular and diffuse. The former can be a single nodule or multiple nodules; the latter is similar in morphology to pneumonia lesions. For the nodular type with limited range, surgical resection has a better effect.