What is cancer?
Cancer is an umbrella term for a large group of diseases caused when abnormal cells divide rapidly, and spread to other tissue and organs. Cancer is one of the leading causes of death in the world. They have the potential to invade or spread to other parts of the body through metastasis. These contrast with benign tumors, which do not spread.
Possible signs and symptoms can be:
- abnormal bleeding
- prolonged cough
- unexplained weight loss
- change in bowel movements
Note: While these symptoms may indicate cancer, they can also have other causes.
Science behind cancer
Trillions of cells make up a healthy body and each cell has a specific life cycle, reproducing and dying off in a way that is determined by the type of cell. Cancer disrupts this process and leads to abnormal growth in cells. It’s caused by changes or mutations in DNA that are not corrected by the cell’s repair machinery.
Mutations can cause cells to divide uncontrollably, causing tumors to form. Although some tumors are benign and do not spread to neighboring tissues, sometimes, they are malignant and cancerous, i.e., they can invade other parts of the body.
Some cancer cells can also migrate through the bloodstream or lymphatic system to distant areas of the body. This process is called metastasis. Cancers that have metastasized are considered more advanced than those that have not, tend to be harder to treat and are more fatal.
Causes of cancer
Some common causes of cancer are listed below:
- Tobacco is a common cause of cancer and is responsible for about 22% of cancer deaths.
- Obesity, poor diet, lack of physical activity or excessive drinking of alcohol cause about10% of the cancer cases.
- Ionizing radiation and environmental pollutants are also known carcinogens.
- In the developing world, 15% of cancers are due to infections such as Helicobacter pylori, hepatitis B, hepatitis C, human papillomavirus infection, Epstein–Barr virus and human immunodeficiency virus (HIV).
- Approximately 5–10% of cancers are due to inherited genetic defects.
Types of cancer
Cancers are named for the area in which they begin and the type of cell they are made of, even if they spread to other parts of the body. For example, a cancer that begins in the lungs and spreads to the liver is still called lung cancer. There are also several clinical terms used for certain general types of cancer:
- Carcinoma is a cancer that starts in the skin or the tissues that line other organs.
- Sarcoma is a cancer of connective tissues such as bones, muscles, cartilage, and blood vessels.
- Leukemia is a cancer of bone marrow, which creates blood cells.
- Lymphoma and myeloma are cancers of the immune system.
The most common types of treatment are:
- Surgery: Surgically removes as much of the cancer as possible.
- Chemotherapy: Uses medications that are toxic to cells to kill rapidly-dividing cancer cells.
- Radiation Therapy: Uses powerful, focused beams of radiation inside (brachytherapy) or outside (external beam radiation) your body to kill cancer cells.
- Stem Cell (Bone Marrow) Transplant: Repairs diseased bone marrow with healthy stem cells. Stem cells are undifferentiated cells that can have a variety of functions. These transplants allow doctors to use higher doses of chemotherapy to treat the cancer.
- Immunotherapy (Biological Therapy): Uses antibodies to help your body’s immune system recognize cancer so it can fight it off.
- Hormone Therapy: Removes or blocks hormones that fuel certain cancers to stop cancer cells from growing.
- Targeted Drug Therapy: Uses drugs to interfere with certain molecules that help cancer cells grow and survive.
- Clinical Trials: Investigates new ways to treat cancer.
- Alternative Medicine: Used to decrease symptoms of cancer and side effects of cancer treatment, such as nausea, fatigue, and pain. Alternative medicine includes acupuncture, hypnosis, massage, yoga, meditation and other relaxation techniques.