What are signs and symptoms?
Signs and symptoms are both signals of injury, illness, disease, or that something is not right in the body.
A sign is a signal that can be seen by someone else-maybe a loved one, or a doctor, nurse, or other health care professional. For example, fever, fast breathing, and abnormal lung sounds heard through a stethoscope may be signs of pneumonia.
A symptom is a signal that is felt or noticed by the person who has it, but may not be easily seen by anyone else. For example, weakness, aching, and feeling short of breath may be symptoms of pneumonia.
Having one sign or symptom may not be enough to figure out what's causing it. For example, a rash in a child could be a sign of a number of things, such as poison ivy, measles, a skin infection, or a food allergy. But if the child has the rash along with other signs and symptoms like a high fever, chills, achiness, and a sore throat, then a doctor can get a better picture of the illness. Sometimes, a patient's signs and symptoms still don't give the doctor enough clues to be sure what is causing the illness. Then medical tests, such as x-rays, blood tests, or a biopsy may be needed.
How does cancer cause signs and symptoms?
Cancer is a group of diseases that can cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, how big it is, and how much it affects the organs or tissues. If a cancer has spread (metastasized ), signs or symptoms may appear in different parts of the body.
As a cancer grows, it can begin to push on nearby organs, blood vessels, and nerves. This pressure causes some of the signs and symptoms of cancer. If the cancer is in a critical area, such as certain parts of the brain, even the smallest tumor can cause symptoms.
But sometimes cancer starts in places where it will not cause any signs or symptoms until it has grown quite large. Cancers of the pancreas, for example, usually do not cause symptoms until they grow large enough to press on nearby nerves or organs (this causes back or belly pain). Others may grow around the bile duct and block the flow of bile. This causes the eyes and skin to look yellow (jaundice ). By the time a pancreatic cancer causes signs or symptoms like these, it's usually in an advanced stage. This means it has grown and spread beyond the place it started-the pancreas.
A cancer may also cause symptoms like fever, extreme tiredness (fatigue ), or weight loss. This may be because cancer cells use up much of the body's energy supply, or they may release substances that change the way the body makes energy from food. Or the cancer may cause the immune system to react in ways that produce these signs and symptoms.
Sometimes, cancer cells release substances into the bloodstream that cause symptoms which are not usually linked to cancer. For example, some cancers of the pancreas can release substances that cause blood clots in veins of the legs. Some lung cancers make hormone-like substances that raise blood calcium levels. This affects nerves and muscles, making the person feel weak and dizzy.