OVERVIEW

What is lung cancer?

Primary bronchogenic carcinoma, commonly referred to as lung cancer, is a malignant tumor originating in the airways (including the trachea and bronchi) or lungs. It can cause symptoms such as coughing, hemoptysis, chest pain, fever, fatigue, and weight loss, with a high mortality rate^[1].

Lung cancer is closely associated with smoking and air pollution, and secondhand smoke is equally dangerous. Additionally, long-term exposure to cooking fumes, chemicals such as chromium, nickel, or asbestos, excessive ionizing radiation, or a family history of lung cancer can also increase the risk^[1].

Currently, lung cancer is primarily treated with surgery, combined with chemotherapy, radiotherapy, targeted therapy, etc. Prognosis largely depends on the timing of treatment and the patient's condition. Early diagnosis and treatment may lead to a relatively good prognosis, while delayed treatment can result in distant metastasis and a poorer prognosis^[2].

What are the types of lung cancer?

Based on histopathology, it can be classified into:

1. Non-small cell lung cancer: Includes squamous cell carcinoma, adenocarcinoma, large cell carcinoma, etc.^[2].
   • Squamous cell carcinoma: Generally grows slowly, metastasizes late, and has more opportunities for surgical resection^[2].
   • Adenocarcinoma: Tends to metastasize early through the bloodstream^[2].
   • Large cell carcinoma: Metastasizes relatively late, with better chances of surgical removal^[2].
2. Small cell lung cancer: Rapidly proliferates and can metastasize distantly at an early stage^[2].

Is lung cancer common?

Yes. According to the latest data from the WHO GLOBOCAN, the incidence of lung cancer in China exceeds 40 per 100,000 people, meaning that more than 40 out of every 100,000 individuals have lung cancer, with a higher prevalence among men over 40 years old^[3,4].

SYMPTOMS

What are the early warning signs of lung cancer?

When the following symptoms appear in the body, be alert to the possibility of lung cancer. Do not delay, and it is recommended to seek medical attention as soon as possible to obtain professional help from a doctor.

• A cough lasting more than 2–3 weeks or unresponsive to standard treatment;
• Chest tightness or shortness of breath after activity;
• Persistent chest or shoulder/back pain;
• Blood-streaked sputum or coughing up blood;
• Pneumonia lasting for an extended period or unresponsive to standard treatment;
• Unexplained fever, hoarseness, fatigue, poor mental state, weight loss, etc.^[3].

What are the common manifestations of lung cancer?

The symptoms of lung cancer are closely related to the size, type, stage, and metastasis of the tumor. 5%–15% of patients may have no symptoms and are only discovered during routine physical examinations or chest imaging. For symptomatic patients, the manifestations typically include the following^[2]:

• Symptoms caused by the primary tumor: These include cough, blood-streaked sputum or even massive hemoptysis, shortness of breath, difficulty breathing, chest pain, fever, and weight loss. Among these, cough is the earliest symptom, usually presenting as a dry, irritating cough with little or no sputum^[2].
• Symptoms caused by tumor invasion of adjacent organs or structures: When the tumor compresses the recurrent laryngeal nerve, it may cause hoarseness; when it compresses the esophagus, it may lead to difficulty swallowing^[2].
• Symptoms caused by distant metastasis: When the tumor metastasizes to the central nervous system, symptoms such as headache, nausea, vomiting, dizziness, or hemiplegia may occur; metastasis to the bones may cause local pain and tenderness; metastasis to the digestive system may result in loss of appetite or abdominal pain; metastasis to the lymph nodes often causes lymphadenopathy and pain^[2].

What complications can lung cancer cause?

• Pleural effusion: When lung cancer invades the pleura, it can cause pleural effusion, leading to symptoms such as chest tightness, difficulty breathing, and fever^[2].
• Superior vena cava syndrome: This occurs when the lung cancer mass compresses or directly invades the superior vena cava, manifesting as facial swelling (similar to the sensation of prolonged inversion), facial edema, difficulty breathing, blurred vision, dizziness, and headache^[2].
• Pancoast tumor syndrome: Lung cancer located at the apex of the lung may damage the sympathetic nerves, leading to this syndrome, which presents as shoulder pain, one-sided eyeball retraction, one-sided pupil constriction, one-sided facial sweating reduction, and hand muscle atrophy^[2].
• Paraneoplastic syndrome: Some lung cancer cells can secrete specific endocrine hormones, leading to paraneoplastic syndrome. Symptoms include dry mouth, nausea, constipation, polyuria, irritability, confusion, and even coma or sudden death^[2].

CAUSES

How does lung cancer develop?

Normal tracheal, bronchial, and alveolar cells undergo a series of genetic mutations due to various factors, causing cells that would normally "age and die automatically" to become "immortal" and grow rapidly, forming cell masses, which develop into lung cancer.

Cancer cells are highly aggressive. They not only grow in the lungs but also invade territories "exclusive" to organs such as the brain, liver, and bones, expanding like an invader. This is lung cancer metastasis.

What are the common causes of lung cancer?

The exact etiology and pathogenesis of lung cancer remain unclear, but studies suggest it may be related to the following factors^[2]:

• Smoking and passive smoking: Smoking is currently recognized as the most significant risk factor for lung cancer. Tobacco releases multiple carcinogens during combustion, and long-term inhalation increases the likelihood of lung cancer. Passive smoking is also a risk factor, particularly among women^[3].
• Environmental pollution:
  • Outdoor environmental pollution: Industrial exhaust and vehicle emissions in cities contain carcinogens. Studies have found higher lung cancer incidence rates in urban areas compared to rural areas^[2,5].
  • Indoor environmental pollution: Indoor pollution mainly includes fuel combustion and cooking fumes. Incomplete fuel combustion and fumes produce various carcinogens, increasing lung cancer risk^[3].
• Occupational factors: Certain occupations involving long-term exposure to asbestos, arsenic, chromium, nickel, uranium, radium, ionizing radiation, and microwave radiation can elevate lung cancer incidence^[2].
• Genetic and gene mutations: Familial clustering of lung cancer cases suggests a role for genetic factors. Additionally, lung cancer involves a series of gene mutations, with key oncogenes including the RAS gene family and Myc gene family^[2,3].
• Other factors: Diet, physical activity, psychosocial factors, infections, and lung diseases (e.g., chronic obstructive pulmonary disease) may also contribute to lung cancer.

Who is at higher risk for lung cancer?

• Long-term active or passive smokers: These individuals are at higher risk due to prolonged inhalation of tobacco carcinogens^[3].
• Those with long-term exposure to carcinogens: Occupational exposure to asbestos, arsenic, chromium, nickel, ionizing radiation, etc., increases susceptibility^[2].
• Individuals with a family history of lung cancer: Familial clustering indicates a higher likelihood of developing the disease^[2,3].

DIAGNOSIS

Under What Circumstances Should Lung Cancer Patients Seek Medical Attention?

Generally, coughing is the earliest symptom of lung cancer. Therefore, patients should seek prompt medical evaluation if they experience symptoms such as a dry, irritating cough with little or no phlegm, or coughing up blood, and avoid delays in treatment.

Additionally, if a physical examination (particularly a chest CT scan) reveals lung nodules, further medical evaluation is necessary.

How Do Doctors Diagnose Lung Cancer?

Typically, doctors rely on the patient's smoking history (including passive smoking), personal history (such as prolonged exposure to carcinogens like asbestos, chromium, nickel, or ionizing radiation), family history, and clinical symptoms. They also combine these with blood tests, X-rays, CT scans, MRI scans, and histopathological examinations to diagnose the condition^[3].

What Diagnostic Methods Are Used for Lung Cancer?

1. Blood tests: These include complete blood count, kidney and liver function tests, and tumor marker tests to assess the patient's general condition.

2. Imaging tests:

   • X-rays: One of the most common methods, but their low resolution limits their effectiveness in detecting early-stage lung cancer^[2].
   • CT scans: Offer higher resolution than X-rays and can effectively detect early lung cancer. Contrast-enhanced CT scans also aid in clinical staging^[2].
   • MRI scans: Useful for determining the relationship between tumors and major blood vessels and are superior in detecting brain or spinal metastases^[2,3].
   • PET-CT scans: The best method for diagnosing lung cancer staging, assessing prognosis, precisely locating lesions, and identifying metastases, though they are more expensive^[1,3].

3. Sputum cytology: Cancer cells shed from lung tumors may be coughed up in sputum. Finding these cells confirms the diagnosis. However, this method requires repeated sampling and must involve deep airway sputum^[1,2].

4. Histopathological examination: Typically performed via bronchoscopy or lung biopsy to obtain tissue samples, which are then examined under a microscope to detect cancer cells^[2]. This method has a high diagnostic accuracy but is invasive.

In addition to the above tests, other diagnostic tools such as ultrasound, bone scans, and thoracoscopy may be used to aid in diagnosis.

How Is Lung Cancer Staged? What Do the Stages Mean?

Lung cancer is commonly staged using the TNM system. A typical clinical notation is T1N2M1, Stage IV.

• T indicates the size of the primary tumor, with higher subscript numbers representing larger tumors.
• N indicates the extent of lymph node involvement, with higher numbers indicating greater involvement.
• M indicates metastasis to other organs, where 0 means none and 1 means present.

Stages are categorized as I, II, III, or IV, with higher numbers indicating more advanced disease, worse prognosis, and shorter survival^[1].

What Diseases Are Easily Confused with Lung Cancer?

• Tuberculosis: Both can present with cough, sputum, chest pain, and hemoptysis, with similar X-ray findings. Distinguishing tests include Mycobacterium tuberculosis detection, CT scans, and MRI scans^[1].
• Pneumonia: Both may cause cough and sputum, and chronic pneumonia-induced inflammatory pseudotumors can resemble lung cancer. However, pneumonia usually responds to antibiotics. Blood tests, MRI, and histopathology can help differentiate them^[2].
• Lung abscess: When lung cancer undergoes central necrosis, X-ray findings may resemble a lung abscess. However, lung abscesses typically present acutely with copious sputum, chills, and high fever. Bronchoscopy and sputum cytology aid in differentiation^[2].
• Other lung tumors: Such as fibromas, hamartomas, and bronchial adenomas, which may resemble lung cancer on X-rays. Histopathological examination is key for differentiation^[1].

TREATMENT

Which department should I visit for lung cancer?

Respiratory medicine, thoracic surgery, or oncology.

How is lung cancer treated?

Generally, doctors will develop a planned and rational approach based on the patient's physical condition, tumor type, and extent of invasion, utilizing methods such as surgery, radiotherapy, chemotherapy, and molecular targeted therapy to maximize survival time, improve survival rates, and enhance quality of life^[3].

What is surgical treatment for lung cancer?

It refers to the removal of lung cancer tumor tissue through surgery. Early-stage patients may achieve a cure through surgery. In recent years, the application of thoracoscopic techniques in lung cancer surgery has spared many patients the "pain of open-chest surgery," though it is not suitable for everyone. Surgeons will choose the surgical method based on the patient's condition and overall health^[1]. Common surgical methods include segmentectomy, lobectomy, and pneumonectomy^[1].

Segmentectomy involves removing less than one lobe of the lung, with lower surgical risks but a higher recurrence rate, making it suitable for very early-stage lung cancer patients^[1].

Lobectomy and pneumonectomy have lower recurrence rates but may result in relatively poorer quality of life for patients^[1].

Do lung cancer patients need further treatment after surgery?

Whether additional treatment is needed after surgery depends on the stage of the lung cancer. Since the majority of lung cancer patients in China are diagnosed at an advanced stage, most still require follow-up treatment post-surgery.

What is chemotherapy for lung cancer?

Chemotherapy involves using chemical drugs to kill tumor cells. Chemotherapy drugs include oral and intravenous forms, with the latter being more common. The advantage of chemotherapy is that the drugs enter the bloodstream, not only targeting lung lesions but also killing tumor cells that have spread throughout the body^[2].

Common chemotherapy drugs include cisplatin, carboplatin, paclitaxel, and docetaxel, which can delay tumor progression and improve long-term survival rates post-surgery. They are generally suitable for small-cell lung cancer patients, those ineligible for surgery, or those with lymph node or distant metastases. However, side effects may include hair loss, nausea, vomiting, and hematuria^[2].

Can I skip chemotherapy due to its feared side effects?

Currently, scientists and doctors worldwide agree that chemotherapy can delay recurrence and metastasis in lung cancer patients and extend survival^[2]. Avoiding chemotherapy due to fear of side effects is counterproductive.

In clinical practice, doctors take measures to prevent or mitigate chemotherapy side effects. Following medical advice and communicating your experience with the doctor are also crucial for reducing side effects.

What is targeted therapy for lung cancer?

Targeted therapy is also a form of drug treatment. After taking targeted drugs, they act on specific cancer-causing sites, killing tumor cells without harming normal cells. It is generally suitable for non-small-cell lung cancer patients, those ineligible for surgery, or those with lymph node or distant metastases. Common targeted drugs include erlotinib, gefitinib, and bevacizumab, which can inhibit tumor growth and cause regression. Possible side effects include rash, diarrhea, nausea, and vomiting^[2].

What is immunotherapy for lung cancer?

It involves using drugs to activate the body's immune system to kill cancer cells. Common drugs include PD-1 or PD-L1 inhibitors, suitable for advanced or metastatic non-small-cell lung cancer patients. Possible side effects include hypothyroidism, hyperthyroidism, rash, and interstitial pneumonia^[3].

What is radiotherapy for lung cancer?

Radiotherapy uses radiation to kill cancer cells, eliminate tumors, extend survival, and improve quality of life. It is a localized treatment with relatively fewer side effects. Depending on the patient's condition, it can be used alone or combined with chemotherapy. It is suitable for patients ineligible for surgery, those with lymph node or distant metastases, or as adjuvant therapy before or after surgery^[1,2].

Can lung cancer be cured?

Not necessarily.

The prognosis depends on the timing of treatment and the patient's condition. Early-stage lung cancer can often be cured through surgery. However, symptoms typically appear at an advanced stage, leading to poorer outcomes^[1,2].

How often should lung cancer patients undergo follow-up exams?

For early- and mid-stage lung cancer patients after comprehensive treatment (including surgery), follow-ups are generally recommended every three months for the first two years, every six months for years two to five, and annually thereafter^[3]. Chest CT scans are the primary method, with subsequent treatment plans and follow-up schedules determined based on the results.

DIET & LIFESTYLE

What should lung cancer patients pay attention to after surgery?

• Keep the wound clean and dry after surgery, avoid contact with water. For those with drainage tubes, ensure the tubes remain unobstructed, avoid kinking or bending, and make sure the drainage tube position is not higher than the wound plane.
• The chest will be tightly bandaged after surgery. Patients should closely monitor for symptoms such as chest tightness or difficulty breathing.
• Rest adequately after surgery. Once the condition allows, actively engage in lung function exercises under medical guidance, such as deep breathing initially, and later using a respiratory trainer for blowing or inhaling exercises.

What should lung cancer patients pay attention to in daily life?

• Strictly follow medical instructions for medication and follow-up visits. Do not reduce, change, or stop medication without authorization. Closely monitor for adverse drug reactions during treatment and seek medical attention promptly if abnormalities occur.
• Maintain a clean and tidy living environment with good ventilation.
• Avoid smoking and exposure to harmful substances such as cooking fumes and vehicle exhaust.
• Strengthen lung function through exercises like Tai Chi, breathing exercises, or square dancing, but ensure moderate intensity and avoid strenuous activities.
• Maintain a positive mindset. Relax by listening to music, watching movies, etc., and avoid excessive focus on the disease itself to prevent emotional distress and fluctuations.

What dietary precautions should lung cancer patients take?

There are no special dietary requirements for this condition; a healthy and light diet is sufficient.

Consume more low-fat, low-cholesterol, and high-quality protein foods, as well as fresh vegetables and fruits such as spinach, broccoli, apples, lean meat, eggs, and milk to enhance nutrition and promote recovery.

PREVENTION

What are the preventive measures for lung cancer?

• Quit smoking. Also avoid exposure to secondhand smoke.
• Turn on the range hood or open windows for ventilation while cooking.
• People who are exposed to carcinogens due to work requirements should take protective measures during work.
• Get regular health check-ups, and high-risk groups for lung cancer should increase the frequency of check-ups.
• People with lung diseases should seek medical treatment early and actively treat the underlying condition.
• Maintain a healthy diet, regular routine, exercise, and a positive mood.

How is lung cancer screened?

Low-dose CT (LDCT) is a common screening method for lung cancer, with high sensitivity, and is suitable as a routine screening method. For suspicious lesions detected by CT, further examination with fiberoptic bronchoscopy may be performed^[6].

Who are the key populations for lung cancer screening?

• People aged 45–75: Since the incidence and mortality of lung cancer increase significantly after age 45 and decline after age 75, screening is recommended for this age group.
• Smokers: It is recommended that people with a smoking history of ≥20 pack-years undergo lung cancer screening. Heavy smokers may further undergo fluorescence bronchoscopy.
• Others: Those chronically exposed to secondhand smoke or cooking fumes, those exposed to high-risk carcinogens like radon, arsenic, chromium, or cadmium, individuals with a history of other malignancies, those with a family history of lung cancer, and those with a history of other chronic lung diseases^[6].

How often should lung cancer screening be done?

The recommended screening interval is 1 year. If the annual screening results are normal, it is recommended to continue screening every 1–2 years^[6].