Complications of Lung Cancer

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Complications: Lung cancer may cause wheezing by narrowing the airway. Blockage of an airway by a tumor may lead to the collapse of the part of the lung that the airway supplies, a condition called atelectasis (see Atelectasis). Other consequences of a blocked airway are shortness of breath and pneumonia, which may result in coughing, fever, and chest pain. If the tumor grows into the chest wall, it may produce persistent, unrelenting chest pain. Fluid containing cancerous cells can accumulate in the space between the lung and the chest wall (pleural effusions—see Pleural Disorders: Pleural Effusion). Large amounts of fluid can lead to shortness of breath. If the cancer spreads throughout the lungs, the levels of oxygen in the blood drop and become low, causing shortness of breath and eventually enlargement of the right side of the heart and possible heart failure (cor pulmonale—see Pulmonary Hypertension:Pulmonary Hypertension).

Lung cancer may grow into certain nerves in the neck, causing a droopy eyelid, small pupil, sunken eye, and reduced perspiration on one side of the face—together these symptoms are called Horner's syndrome (see Autonomic Nervous System Disorders: Horner's Syndrome). Cancers at the top of the lung may grow into the nerves that supply the arm, making the arm painful, numb, and weak. Tumors in this location are often called Pancoas't tumors. When the tumor grows into nerves in the center of the chest, the nerve to the voice box may become damaged, making the voice hoarse.

Lung cancer may grow into or near the esophagus, leading to difficulty swallowing or pain with swallowing.

Lung cancer may grow into the heart or in the midchest (mediastinal) region, causing abnormal heart rhythms, blockage of blood flow through the heart, or fluid in the sac surrounding the heart (pericardial sac).

The cancer may grow into or compress one of the large veins in the chest (the superior vena cava); this condition is called superior vena cava syndrome. Obstruction of the superior vena cava causes blood to back up in other veins of the upper body. The veins in the chest wall enlarge. The face, neck, and upper chest wall—including the breasts—can swell, causing pain. The condition can also produce shortness of breath, headache, distorted vision, dizziness, and drowsiness. These symptoms usually worsen when the person bends forward or lies down.

Lung cancer may also spread through the bloodstream to other parts of the body, most commonly the liver, brain, adrenal glands, spinal cord, or bones. The spread of lung cancer may occur early in the course of disease, especially with small cell lung cancer. Symptoms—such as headache, confusion, seizures, and bone pain—may develop before any lung problems become evident, making an early diagnosis more complicated.

Paraneoplastic syndromes (see What Are Paraneoplastic Syndromes?) consist of effects that are caused by cancer but occur far from the cancer itself, such as in nerves and muscles. These syndromes are not related to the size or location of the lung cancer and do not necessarily indicate that the cancer has spread outside the chest. These syndromes are caused by substances secreted by the cancer (such as hormones, cytokines, and various other proteins).