What Is Cancer?

The Definition of Cancer

Cancer is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body.

Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and multiply (through a process called cell division) to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.

Sometimes this orderly process breaks down, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumors, which are lumps of tissue. Tumors can be cancerous or not cancerous (benign).

Cancerous tumors spread into, or invade, nearby tissues and can travel to distant places in the body to form new tumors (a process called metastasis). Cancerous tumors may also be called malignant tumors. Many cancers form solid tumors, but cancers of the blood, such as leukemias, generally do not.

Benign tumors do not spread into, or invade, nearby tissues. When removed, benign tumors usually don’t grow back, whereas cancerous tumors sometimes do. Benign tumors can sometimes be quite large, however. Some can cause serious symptoms or be life threatening, such as benign tumors in the brain.

cancer is curable or not

Whether a person's cancer can be cured depends on the type and stage of the cancer, the type of treatment they can get, and other factors. Some cancers are more likely to be cured than others. But each cancer needs to be treated differently. There isn't one cure for cancer

Differences between Cancer Cells and Normal Cells

Cancer cells differ from normal cells in many ways. For instance, cancer cells:

• grow in the absence of signals telling them to grow. Normal cells only grow when they receive such signals.
• ignore signals that normally tell cells to stop dividing or to die (a process known as programmed cell death, or apoptosis).
• invade into nearby areas and spread to other areas of the body. Normal cells stop growing when they encounter other cells, and most normal cells do not move around the body.
• tell blood vessels to grow toward tumors. These blood vessels supply tumors with oxygen and nutrients and remove waste products from tumors.
• hide from the immune system. The immune system normally eliminates damaged or abnormal cells.
• trick the immune system into helping cancer cells stay alive and grow. For instance, some cancer cells convince immune cells to protect the tumor instead of attacking it.
• accumulate multiple changes in their chromosomes, such as duplications and deletions of chromosome parts. Some cancer cells have double the normal number of chromosomes.
• rely on different kinds of nutrients than normal cells. In addition, some cancer cells make energy from nutrients in a different way than most normal cells. This lets cancer cells grow more quickly.
• Many times, cancer cells rely so heavily on these abnormal behaviors that they can’t survive without them. Researchers have taken advantage of this fact, developing therapies that target the abnormal features of cancer cells. For example, some cancer therapies prevent blood vessels from growing toward tumors, essentially starving the tumor of needed nutrients.

Types of Cancer

• Carcinoma
• Sarcoma
• Leukemia
• Lymphoma
• Multiple Myeloma
• Melanoma
• Brain and Spinal Cord Tumors

Other Types of Tumors

• Germ Cell Tumors
• Neuroendocrine Tumors
• Carcinoid Tumors

What are the 3 main treatments for cancer?

• Surgery

Surgical oncology is the branch of surgery applied to oncology; it focuses on the surgical management of tumors, especially cancerous tumors.

• Chemotherapy

Chemotherapy is a cancer treatment where medicine is used to kill cancer cells. There are many different types of chemotherapy medicine, but they all work in a similar way. They stop cancer cells reproducing, which prevents them from growing and spreading in the body

• Radiation

Radiation therapy (also called radiotherapy) is a cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors.