The clinical presentation of lung cancer is diverse but not specific, which often leads to a delay in the diagnosis of lung cancer. Peripheral lung cancer usually does not show any symptoms and is often detected during health checkups or chest imaging for other diseases. The clinical manifestations of lung cancer can be summarized as symptoms caused by the local growth of the primary tumor itself, symptoms caused by the invasion of adjacent organs and structures by the primary tumor, symptoms caused by distant metastases, and extra-pulmonary manifestations of lung cancer (e.g., paraneoplastic syndrome).
- Symptoms caused by the local growth of the primary tumor itself
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Such symptoms and signs include: (1) cough, which is the most common symptom of lung cancer patients at the time of consultation, with more than 50 lung cancer patients having cough at the time of diagnosis. (2) Hemoptysis. Approximately 25-40% of lung cancer patients will present with hemoptysis, which usually presents as blood in the sputum, and hemoptysis is rare. Hemoptysis is the most suggestive symptom of lung cancer. (3) Dyspnea. The mechanisms of dyspnea may include the following: reduction of alveolar area due to primary tumor expansion, obstruction of the airways by central lung cancer or metastatic lymph nodes, atelectasis and obstructive pneumonia, intrapulmonary lymphatic vessel dissemination, pleural and pericardial effusion, and pneumonia. (4) Fever, fever can be caused by necrosis of tumor tissue, and fever can also be caused by secondary pneumonia caused by tumor. (5) Wheezing. If the tumor is located in the large airway, especially in the main bronchus, it may cause limited wheezing symptoms.
- Symptoms caused by primary tumor invading adjacent organs and structures
- Symptoms due to distant metastases of tumors
- Extrapulmonary manifestations of lung cancer
- Extrapulmonary manifestations of lung cancer
The primary tumor directly invades adjacent structures such as the chest wall, diaphragm, pericardium, phrenic nerve, recurrent laryngeal nerve, superior vena cava, esophagus, or metastatic enlarged lymph nodes mechanically compressing the above structures, and specific symptoms and signs may appear. These include: pleural effusion, hoarseness, phrenic nerve palsy, dysphagia, superior vena cava obstruction syndrome, pericardial effusion, Pancoast syndrome, etc.
The most common symptoms are headache, nausea, and vomiting due to central nervous system metastases. Bone metastases usually present with more intense and progressive pain, etc.
In addition to symptoms caused by local progression of the tumor and symptoms caused by extrathoracic metastases, patients with lung cancer may also present with paraneoplastic syndrome. Paraneoplastic syndromes associated with lung cancer are seen in approximately 10 to 20 patients with lung cancer and are more common in small cell lung cancer. They are commonly associated with ectopic endocrine, osteoarticular metabolic abnormalities and, in some cases, neuromuscular conduction disorders. The development of paraneoplastic syndrome does not necessarily correlate positively with the extent of tumor disease and may sometimes precede the clinical diagnosis of lung cancer. In lung cancer with combined paraneoplastic syndrome that can be surgically resected, the recurrence of symptoms is an important indicator of tumor recurrence.