Cancer

(a) Definition

The name cancer actually refers to numerous distinct diseases characterized by abnormal cell growth and differentiation. Cancer evolves from irrepressible growth of abnormal cells that have mutated from normal tissues. Cancer is the result of a multi-step process called carcinogenesis, which occurs over a long period of time. The state of the cancer is highly dependent on the cell type and organ from which it is derived.

(b) Risk Factors and Incidence

Frequently doctors cannot explain why one person develops cancer and another foes not. Much research shows that certain risk factors increase the chance that a person will develop cancer. The most common factors for becoming prone for cancer are growing older, tobacco, sunlight, certain chemicals, family history, alcohol, and a poor diet. According to Healthline.com there are more than 8 million new cases and 5 million deaths from cancer per year. The incidence of cancer is nearly 100,000 new cases each year. Except in rare cases, cancer incidence, prevalence, and mortality rates are higher in industrialized countries such as the U.S. and Europe; compared to developing countries like China and African nations. Incidence rates for certain cancers can be considerably affected by the use of screening procedures to identify asymptomatic diseases.

(c) Symptoms

Cancer is groups of diseases that can cause almost any type of sign or symptom. The signs and symptoms can vary on the size of the cancer, where the cancer is, and how much it affects the surrounding organs and structures. If a cancer spreads, then symptoms can appear in different parts of the body. When a cancer grows, it begins to push on nearby organs, blood vessels, or nerves. The pressure it creates can determine 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 immense symptoms. A cancer may also cause symptoms such as fever, fatigue, or weight loss. This may happen because the cancer cells use up much of the body's energy supply or because, 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 headaches, weakness and dizziness.