What Is Cancer?
Cancer is the general name for a group of more than 100 diseases. Although there are many kinds of cancer, all cancers start because abnormal cells grow out of control. Untreated cancers can cause serious illness and death.
What are signs and symptoms?
Signs and symptoms are both signals of injury, illness, disease – signals 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’s 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’s 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 won’t cause any signs or symptoms until it has grown quite large. Cancers of the pancreas, for example, usually don’t 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. Cancer can also 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 that 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.
How are signs and symptoms helpful?
Treatment works best when cancer is found early – while it’s still small and is less likely to have spread to other parts of the body. This often means a better chance for a cure, especially if the cancer can be removed with surgery.
A good example of the importance of finding cancer early is melanoma skin cancer. It can be easy to remove if it has not grown deep into the skin. The 5-year survival rate (percentage of people who live at least 5 years after diagnosis) at this early stage is around 98%. Once melanoma has spread to other parts of the body, the 5-year survival rate drops to about 16%.
Sometimes people ignore symptoms. Maybe they don’t know that the symptoms could mean something is wrong. Or they might be frightened by what the symptoms could mean and don’t want to get medical help. Maybe they just can’t afford to get medical care.
Some symptoms, such as tiredness or coughing, are more likely caused by something other than cancer. Symptoms can seem unimportant, especially if there’s a clear cause or the problem only lasts a short time. In the same way, a person may reason that a symptom like a breast lump is probably a cyst that will go away by itself. But no symptom should be ignored or overlooked, especially if it has lasted a long time or is getting worse.
Most likely, symptoms are not caused by cancer, but it’s important to have them checked out, just in case. If cancer is not the cause, a doctor can help figure out what the cause is and treat it, if needed.
But keep in mind, even if you have these recommended tests, it’s still important to see a doctor if you have any symptoms.