Symptoms

At first, cancer, as a tiny mass of cells, produces no symptoms whatsoever. When cancer grows in an area with a lot of space, such as in the wall of the large intestine, it may not cause any symptoms until it becomes quite large. In contrast, a cancer growing in a more restricted space, such as on a vocal cord, may cause symptoms (such as hoarseness) when it is relatively small.

Cancers produce symptoms by growing into and thus irritating or destroying other tissues, putting pressure on other tissues, producing toxic substances, and using energy and nutrients normally available for other bodily functions. Cancer may cause one set of symptoms as it grows in its initial site and cause different symptoms as it spreads (metastasizes) to other parts of the body.

As a cancer grows and spreads throughout the body, a number of complications can result. Some of these complications can be serious and require emergency treatment. Certain complications, called paraneoplastic syndromes, result when substances produced by cancers spread throughout the body.

See the table Some Complications of Cancer.

See the sidebar What Are Paraneoplastic Syndromes?

Pain

Cancers are typically painless at first. However, as they grow, the first symptom is often a mild discomfort, which may steadily worsen into increasingly severe pain as the cancer enlarges. The pain may result from the cancer compressing or eroding into nerves or other structures.

Bleeding

At first, a cancer may bleed slightly because its cells are not well attached to each other and its blood vessels are fragile. Later, as the cancer enlarges and invades surrounding tissues, it may grow into a nearby blood vessel, causing bleeding. The bleeding may be slight and undetectable or detectable only with testing. Such is often the case in early-stage colon cancer. Or, particularly with advanced cancer, the bleeding may be massive and even life threatening.

The site of the cancer determines the site of the bleeding. Cancer anywhere along the digestive tract can cause bleeding in the stool. Cancer anywhere along the urinary tract can cause bleeding in the urine. Other cancers can bleed into internal areas of the body. Bleeding into the lungs can cause the person to cough up blood.

Weight Loss and Fatigue

Typically, a person with cancer experiences weight loss and fatigue, which increase as the cancer progresses. Some people notice weight loss despite a good appetite. Others lose their appetite and may even become nauseated by food. They may become very thin; the loss of underlying fat is particularly noticeable in the face. People with advanced stage cancer are often very tired and sleep many hours a day. If anemia develops, these people may find that they feel tired or become short of breath when exerting themselves.

Swollen Lymph Nodes

As a cancer begins to spread around the body, it may first spread to nearby lymph nodes, which become swollen and may feel hard or rubbery. The swollen lymph nodes may be painless or tender. They may be freely moveable or, if the cancer is more advanced, they may be stuck to the skin above, the deeper layers of tissue below, or to each other.

Depression

Cancer often results in depression. Depression can be related to the symptoms of the illness, a fear of dying, and a loss of independence. Additionally, some cancers may produce substances that directly cause depression by affecting the brain.

Neurologic and Muscular Symptoms

Cancer can grow into or compress nerves, causing any of several neurologic and muscular symptoms, including a change in sensations (such as tingling sensations) or muscle weakness. When a cancer grows in the brain, symptoms may be hard to pinpoint but can include confusion, dizziness, headaches, nausea, changes in vision, and seizures. Neurologic symptoms may also be part of a paraneoplastic syndrome.

Respiratory Symptoms

Cancer can compress or block structures, such as the airways in the lungs, causing shortness of breath or pneumonia and the inability to cough up secretions. Shortness of breath can also occur when the cancer causes bleeding into the lungs or anemia.