Lung cancer is one of the most common and dangerous types of cancer worldwide, and in many cases, its severity is linked to late detection because the disease progresses silently during its early stages. The nature of this cancer and the ways it affects the body vary depending on the type of tumor, its location, and its stage, so the lung cancer symptoms may vary from person to person. Understanding the changes the disease may cause and recognizing them early can help speed up diagnosis and improve the chances of successful treatment and management of the condition.
What is lung cancer?
Lung cancer is a disease caused by the abnormal and uncontrolled growth of lung cells, leading to the formation of masses or tumors that may, over time, impair lung function and affect breathing. This type of cancer usually begins inside the bronchi or small air sacs and may remain localized within the lung or spread to other organs in advanced stages.
Cancer occurs when cells undergo changes or mutations that cause them to divide continuously without stopping, leading to an accumulation of abnormal cells that form tumors. Smoking is the factor most strongly associated with lung cancer; the risk of developing the disease increases with the duration of smoking and the number of cigarettes smoked. However, the disease can also occur in nonsmokers, and quitting smoking helps reduce the risk of developing the disease even after many years of smoking.
When do lung cancer symptoms begin to appear?
Lung cancer may not cause any obvious symptoms in its early stages, so the tumor can grow for a long time before it is detected. Symptoms usually begin to appear as the tumor grows and affects the lung or surrounding tissues, and their nature and severity may vary from person to person depending on the type of cancer, its location, and the stage of the disease. In many cases, the symptoms may resemble those of common respiratory illnesses such as bronchitis or pneumonia, which can lead to a delayed diagnosis.
Early and localized symptoms of lung cancer
Early symptoms of lung cancer may result from the tumor’s direct impact on the lung and respiratory tract; they may be mild or gradual at first before becoming more pronounced as the disease progresses. These symptoms include:
- Persistent or worsening cough: A new cough that doesn’t go away or a cough that gets worse over time.
- Shortness of breath: Feeling labored or tired when breathing, even with minimal exertion.
- Chest pain: Pain that may worsen with deep breathing, coughing, or laughing.
- Coughing up blood: Coughing up blood or rust-colored mucus.
- Wheezing: May be caused by narrowing or blockage of the airways.
- Hoarseness: Persistent changes in voice or unexplained hoarseness.
- Recurrent chest infections: Such as bronchitis or recurrent pneumonia.
- Loss of appetite and unexplained weight loss: Weight loss without dieting or any apparent cause.
- Persistent fatigue and exhaustion: Feeling constantly tired or having low energy.
Advanced localized manifestations of lung cancer
As lung cancer progresses and the tumor grows within the chest, more pronounced local complications may arise as a result of airway obstruction or tumor pressure on adjacent tissues. The most notable of these manifestations include:
- Atelectasis: This can occur due to airway obstruction, causing part of the lung to collapse.
- Malignant pleural effusion: This is a collection of fluid around the lung and can cause severe shortness of breath and chest pain.
- Airway obstruction: This can lead to severe difficulty breathing or recurrent lung infections.
- Invasion of the chest wall or surrounding tissues: This can cause persistent pain in the chest, shoulder, or arm.
- Horner’s syndrome: This can occur with tumors at the apex of the lung, such as a Pancoast tumor, due to the tumor pressing on the nerves supplying the face and eye. This can cause drooping of the eyelid, pupil constriction, and decreased sweating on one side of the face.
- Superior vena cava syndrome: This occurs when a tumor compresses the superior vena cava, the vessel that carries blood from the head and arms back to the heart. This can lead to swelling of the face, neck, or upper chest, along with shortness of breath and sometimes headaches.
Symptoms of lung cancer spreading to other organs
Lung cancer may cause symptoms outside the respiratory system when it spreads to other organs; these symptoms vary depending on where the cancer has spread and how the tumor affects the organ.
Symptoms of lung cancer spreading to the brain
- Headaches: These may occur as a result of the tumor spreading to the brain or due to increased pressure inside the skull.
- Dizziness and balance problems: The patient may feel unsteady, have difficulty walking, or experience loss of balance.
- Seizures: Convulsive seizures can occur if the brain is affected.
- Weakness or numbness in the extremities: Weakness or numbness in the arms or legs may occur as a result of the nervous system being affected.
- Vision or memory problems: Cancer spreading to the brain may cause changes in vision or problems with concentration and memory.
Symptoms of lung cancer spreading to the bones
- Bone pain: This often occurs in the back, pelvis, or limbs and may worsen with movement or at night.
- Weakened bones and increased risk of fractures: Cancer can weaken bone structure and increase the risk of fractures.
- Back or limb pain: This may occur when cancer spreads to the spine or the bones of the limbs.
Symptoms of lung cancer spreading to the liver
- Jaundice: Yellowing of the skin and the whites of the eyes due to liver involvement when lung cancer spreads to the liver.
- Upper right abdominal pain: May occur as a result of lung cancer spreading to the liver and affecting its tissues.
- Loss of appetite and nausea: The patient may experience difficulty eating or feel nauseous after meals.
Symptoms of lung cancer spreading to lymph nodes and blood vessels
- Enlarged lymph nodes: Lumps or swelling may appear in the neck, above the collarbone, or under the armpits.
- Blood Clots: Lung cancer increases the risk of blood clots forming, which can travel to the lungs and cause a serious pulmonary embolism.
Symptoms of lung cancer spreading to the adrenal glands
In many cases, the spread of lung cancer to the adrenal glands may not cause any obvious symptoms, but some patients may experience symptoms related to impaired adrenal gland function, such as:
- Fatigue and general weakness: Feelings of exhaustion or dizziness may occur when adrenal gland function is impaired.
- Weight or appetite disturbances: These may sometimes occur as a result of hormonal changes associated with the adrenal glands.
Paraneoplastic syndromes associated with lung cancer
Lung cancer can sometimes cause disorders that affect organs and tissues distant from the tumor site without direct spread to them; these conditions are known as paraneoplastic syndromes. These syndromes occur as a result of the tumor secreting hormone-like substances or due to an abnormal immune response that affects various body systems, and they are seen more frequently in patients with small-cell lung cancer.
Paraneoplastic syndromes in small cell lung cancer
- Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): This condition occurs when a tumor secretes antidiuretic hormone, leading to low sodium levels in the blood and potentially causing fatigue, nausea, cramps, and mental confusion.
- Ectopic Cushing’s syndrome: This condition results from a tumor secreting ACTH, which stimulates cortisol production, and may cause weight gain, fluid retention, high blood pressure, and high blood sugar.
- Lambert-Eaton syndrome: This condition occurs when the immune system attacks the neuromuscular junction, which can lead to muscle weakness and difficulty walking, swallowing, or speaking.
- Paraneoplastic limbic encephalitis: May cause memory impairment, mood and behavioral changes, and seizures.
- Paraneoplastic cerebellar degeneration: May result in loss of balance, impaired coordination, and difficulty with movement, speech, and swallowing.
Paraneoplastic syndromes in non-small cell lung cancer
- Hypercalcemia: This is often caused by a tumor secreting substances that raise blood calcium levels, and may cause extreme thirst, frequent urination, constipation, nausea, fatigue, and mental confusion.
- Acromegaly: This may occur as a result of the tumor secreting substances that stimulate an increase in growth hormone, which can lead to enlargement of the hands and feet and changes in facial features.
- Hypertrophic pulmonary osteoarthropathy: This may cause clubbing of the fingers and bone and joint pain. It is more commonly seen in certain types of non-small cell lung cancer.
Can non-smokers develop lung cancer symptoms?
Lung cancer can also affect nonsmokers, so persistent respiratory symptoms should not be ignored, even in the absence of a history of smoking. Lung cancer symptoms in non-smokers are similar to those commonly seen in smokers, such as a chronic cough, shortness of breath, chest pain, fatigue, and weight loss. The onset of the disease may be linked to other factors such as chronic exposure to secondhand smoke, air pollution, or certain genetic mutations.
How is lung cancer treated?
Treatment for lung cancer depends on the type and stage of the tumor, the extent of the disease, and the patient’s overall health. Treatment may include surgery, chemotherapy, radiation therapy, immunotherapy, and targeted therapies. Treatment approaches differ between small-cell and non-small-cell lung cancer. More details about lung cancer treatment and small-cell lung cancer treatment can be found in the dedicated articles.
In conclusion, lung cancer symptoms can mimic those of many common respiratory diseases, which sometimes leads to them being overlooked or diagnosed late, particularly in the early stages of the illness. It is crucial to pay attention to persistent or unusual symptoms and consult a doctor when they arise, as this increases the chances of early detection and improves treatment outcomes. The nature of the symptoms can vary among patients, depending on the type of cancer, its stage, and how far it has spread. Therefore, early medical evaluation is essential for reaching an accurate diagnosis and developing an appropriate treatment plan.
Sources:
- American Cancer Society. (n.d.). Signs and symptoms of lung cancer
- MD Anderson Cancer Center. (n.d.). Lung cancer symptoms.
- Blyss Splane, Z. (February 27, 2023). Paraneoplastic syndrome in lung cancer: Types, symptoms, and more. Healthline.
