Cancer : Detailed Guide

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How Does Cancer Produce Signs and Symptoms?

Cancer is a group of diseases that may cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, the size of the cancer, and how much it affects the surrounding organs or structures. If a cancer spreads (metastasizes), then symptoms may appear in different parts of the body.

As a cancer grows, it begins to push on nearby organs, blood vessels, and nerves. This pressure creates 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 produce early symptoms.

Sometimes, however, cancers form in places where there may be no symptoms until the cancer has grown quite large. Pancreas cancers, for example, do not usually grow large enough to be felt from the outside of the body. Some pancreatic cancers do not produce symptoms until they begin to grow around nearby nerves, causing a backache. Others grow around the bile duct, which blocks the flow of bile and leads to a yellowing of the skin known as jaundice. By the time a pancreatic cancer causes these signs or symptoms, it has usually reached an advanced stage.

A cancer may also cause symptoms such as fever, fatigue, or weight loss. This may be caused by cancer cells using up much of the body’s energy supply or releasing substances that change the body’s metabolism. Or the cancer may cause the immune system to react in ways that produce these symptoms.

Sometimes, cancer cells release substances into the bloodstream that cause symptoms not usually thought to result from cancers. For example, some cancers of the pancreas can release substances which cause blood clots to develop in veins of the legs. Some lung cancers make hormone-like substances that affect blood calcium levels, affecting nerves and muscles and causing weakness and dizziness.

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