OVERVIEW

What is lung adenocarcinoma?

Lung adenocarcinoma is a common type of lung cancer that can originate in small bronchi or central airways, grow outside the trachea, or spread along alveolar walls^[1].

The exact cause remains unclear but may be linked to smoking, occupational factors, environmental factors, ionizing radiation, and genetic predisposition.
It is more common in women^[1], typically grows slowly, and has subtle early symptoms. Many patients are diagnosed at intermediate or advanced stages, often missing the optimal window for surgery.

Is lung adenocarcinoma common in China?

Yes. In China, its incidence has been rising annually, accounting for nearly 50% of all lung cancer cases (i.e., ~50 out of 100 lung cancer patients have adenocarcinoma). Globally, ~2.2 million new lung cancer cases were reported in 2020^[2].
The 5-year survival rate for early-stage patients is 53%, but only 15% of cases are detected while the tumor remains localized. The overall 5-year survival rate across all stages remains as low as 16%~17%^[3].

What are the types of lung adenocarcinoma?

According to the 2015 WHO lung tumor classification, it includes:

1. Adenocarcinoma in situ (AIS): Tumor ≤ 3 cm, purely lepidic growth^[4];
2. Minimally invasive adenocarcinoma (MIA): Also ≤ 3 cm, predominantly lepidic growth, but with ≤ 0.5 cm invasive foci (cloud-like shadows on X-rays)^[4];
3. Invasive adenocarcinoma (LPA): At least one invasive focus > 5 mm, with infiltration into lymphatics/vessels. Subtypes include acinar (ACI), papillary (PAP), solid with mucin (SPA), and micropapillary (MPA)^[4].

Which department should suspected or diagnosed patients visit?

Respiratory medicine, oncology, or thoracic surgery.

SYMPTOMS

What are the symptoms of lung adenocarcinoma?

• Cough: An early symptom of lung adenocarcinoma, often presenting as paroxysmal dry cough (intermittent, non-persistent) or irritating dry cough (severe cough without phlegm, with an itchy sensation in the respiratory tract).
• Blood in sputum: Intermittent or continuous blood-streaked phlegm may occur.
• Wheezing: Manifests as a "whistling" sound during breathing, usually caused by bronchial narrowing or partial obstruction due to the tumor.
• Weight loss: In advanced stages, pain may reduce appetite, leading to rapid weight loss.

How does lung adenocarcinoma progress?

Lung adenocarcinoma has an insidious onset and grows slowly. Its progression typically follows: adenocarcinoma in situ → minimally invasive adenocarcinoma → invasive adenocarcinoma.
During this process, cellular and structural atypia (varying degrees of deviation from normal tissue) gradually increase. Approximately 75% of patients are already in the advanced stage at diagnosis^[1].

What complications may lung adenocarcinoma cause?

• Superior vena cava syndrome: Compression or invasion of the superior vena cava (located in the right anterior superior mediastinum of the heart) by the tumor or metastatic lymph nodes obstructs blood flow, leading to swelling of the face, neck, and upper limbs, as well as engorged chest wall veins (visible blood vessels).
• Pleural and pericardial effusion: Caused by tumor invasion or metastasis to the pleura and pericardium, resulting in chest tightness, chest pain, and rapid heartbeat.
• Intracranial metastasis: Brain metastasis often causes central nervous system symptoms such as headache, vomiting, dizziness, diplopia (double vision), hemiplegia, and seizures.
• Bone metastasis: Presents as localized pain and tenderness in the ribs, spine, etc. If the tumor further invades the spinal cord, it may lead to incontinence or paralysis.
• Liver metastasis: Patients may exhibit hepatomegaly or liver pain, often accompanied by loss of appetite, nausea, and weight loss.

CAUSES

What are the high-risk factors for lung adenocarcinoma?

• Smoking: Smoking can impair lung function, damage lung structure, and weaken respiratory immunity. Long-term heavy smoking may trigger genetic mutations in normal lung cells, leading to lung adenocarcinoma.
• Genetic factors: Lung adenocarcinoma is associated with mutations in the EGFR gene, KRAS gene, and EML4-ALK fusion gene. Individuals with a family history of lung adenocarcinoma have a higher risk of developing the disease^[4].
• Environmental factors: Exposure to radon (a radioactive gas found in soil and rocks), asbestos (a heat-resistant mineral fiber), mineral and metal dust, as well as indoor fuel combustion and cooking fumes containing benzopyrene, can cause severe, irreversible damage to the respiratory system and increase the risk of lung adenocarcinoma.
• Ionizing radiation: The lungs are highly sensitive to radiation (e.g., X-rays, alpha rays). High doses of ionizing radiation may elevate the risk of lung adenocarcinoma.
• Disease factors: Conditions such as tuberculosis and chronic obstructive pulmonary disease (COPD) are also associated with the development of lung adenocarcinoma.

Which groups are more susceptible to lung adenocarcinoma?

• Long-term heavy smokers and passive smokers;
• Chefs and individuals who cook frequently;
• Workers in heavy industries such as machinery manufacturing and metallurgy;
• Those exposed to ionizing radiation for extended periods;
• Individuals with pre-existing lung diseases;
• People with a family history of lung adenocarcinoma.

Is lung adenocarcinoma hereditary?

Yes. The development of lung adenocarcinoma is linked to genetic mutations, including those in the EGFR gene, KRAS gene, and EML4-ALK fusion gene. First-degree relatives (parents, children, siblings) of affected individuals have a higher risk of developing the disease^[4].

DIAGNOSIS

How to diagnose lung adenocarcinoma? What tests are needed?

Serum tumor markers: Used for early diagnosis of lung adenocarcinoma. Combined diagnosis of CEA (carcinoembryonic antigen) and CYFRA 21-1 (cytokeratin 19 fragment) can improve the positive diagnostic rate of lung adenocarcinoma^[3].

Pathological examination: The gold standard for diagnosing lung adenocarcinoma. Samples are collected via mediastinoscopy, thoracoscopy, fiberoptic bronchoscopy, or percutaneous lung biopsy and examined under a microscope to detect cancer cells^[3].
Imaging tests: Including CT scans, X-rays, and MRI scans, which can detect abnormal lung lesions early, determine the location, size, and nature of the lesions, and are used for early screening of lung adenocarcinoma while ruling out other benign lung conditions.

Which diseases are easily confused with lung adenocarcinoma? How to differentiate them?

Many benign tumors resemble malignant tumors on imaging, particularly bronchial adenomas and hamartomas, and may present with symptoms like cough, bloody sputum, and wheezing, making them easily confused with lung adenocarcinoma. Pathological examination is required for differentiation.

TREATMENT

Is surgery the primary treatment for early-stage lung adenocarcinoma?

Yes, surgical treatment is the preferred method for early-stage lung adenocarcinoma and can achieve a curative effect. It is suitable for patients whose cancer lesions are confined to one lung and nearby lymph nodes.

Doctors will determine the surgical approach based on the patient's overall health and the extent of tumor invasion. Patients with severe heart or respiratory diseases are generally not recommended for surgery.

What other treatments are available for lung adenocarcinoma?

Main treatments include:

• Chemotherapy: For advanced-stage or metastatic lung adenocarcinoma, chemotherapy drugs such as pemetrexed, cisplatin, docetaxel, or gemcitabine are used. Side effects may include hematuria, nausea, and vomiting. Patients with abnormal liver/kidney function or heart failure are not eligible for chemotherapy^[1].
• Targeted therapy: Patients with positive driver genes (e.g., EGFR, KRAS, or EML4-ALK fusion genes) may receive single-agent targeted drugs like erlotinib, gefitinib, afatinib, osimertinib, or crizotinib^[1]. Common side effects include rash, diarrhea, loss of appetite, dizziness, and vision abnormalities.
• Radiation therapy (radiotherapy): This method uses radiation to induce tumor cell death. The procedure is painless, but high doses or large treatment areas may cause side effects such as nausea, vomiting, fatigue, bone marrow suppression (reduced blood cell counts), and weakened immunity.

How long is the typical treatment cycle for lung adenocarcinoma?

Some early-stage patients may require no further treatment 3–6 months after surgery if no symptoms recur, only regular follow-ups. Intermediate or advanced cases usually need long-term treatment for about 10–12 months, depending on disease progression.

Can lung adenocarcinoma be cured?

Early and intermediate-stage lung adenocarcinoma has a chance of cure, while advanced cases cannot be completely cured. However, standardized treatment can improve quality of life and prolong survival.

DIET & LIFESTYLE

What should patients with lung adenocarcinoma pay attention to in their diet?

Patients should supplement adequate protein, calories, and vitamins, such as milk, lean meat, fish, fresh vegetables, and fruits (e.g., tomatoes, celery, kiwis, apples, etc.), to improve their immune resistance.

If patients have difficulty swallowing normally, they should supplement nutrients through soft foods (e.g., well-cooked dumplings, wontons), semi-liquid foods (e.g., soft noodles, rice porridge), or liquid foods (e.g., rice soup without grains, milk, freshly squeezed fruit juice, etc.). If dietary intake still fails to meet nutritional needs, enteral nutritional supplements can be used to provide nutritional support.

What are the precautions and care measures after surgical treatment for lung adenocarcinoma?

• Postoperative patients must follow medical advice for regular dressing changes or medication. They must not alter drug dosages or discontinue medication without authorization. If adverse reactions such as nausea or vomiting occur, they should promptly inform their doctor for adjustments to the treatment plan.
• Postoperative patients should maintain cleanliness and disinfection of the surgical site. Avoid bathing or contact with water; instead, use a damp towel to clean the body while avoiding the surgical area.
• Balance work and rest, maintain a regular lifestyle, ensure adequate sleep and rest, and avoid excessive fatigue.
• Patients are encouraged to engage in social activities, stay connected with friends, and appropriately vent negative emotions.
• Surgical patients should rest in bed and avoid walking but can perform moderate limb exercises while lying down.

Is follow-up examination necessary for lung adenocarcinoma? How is it conducted?

Yes, follow-up examinations are necessary. Imaging tests are primarily used to monitor treatment efficacy and detect tumor metastasis or recurrence promptly.

Within the first two years after treatment, follow-up examinations should be conducted every 3 months; from years 2 to 5, every 6 months; and after 5 years, annually.

PREVENTION

Can Lung Adenocarcinoma Be Prevented? How to Prevent It?

The exact cause of lung adenocarcinoma is not fully understood, so there are no specific preventive measures. However, certain risk factors can be minimized in daily life and work to reduce the likelihood of developing the disease.

• Try to quit smoking or reduce smoking frequency in daily life, and avoid exposure to secondhand smoke.
• Avoid radiation and harmful chemicals. When unavoidable, take protective measures such as wearing radiation-proof clothing or gloves.
• Install high-quality, high-capacity exhaust systems in kitchens to ensure efficient and rapid removal of cooking fumes. Additionally, maintain natural ventilation in the kitchen to reduce the accumulation of fumes.
• Actively treat underlying lung conditions such as tuberculosis, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis.
• Individuals with a family history of the disease should remain vigilant and undergo regular annual medical check-ups.