Cancer-medically termed as malignant neoplasm is a class of diseases in which a group of cells display the traits of uncontrolled growth and division beyond the normal limits, invasion and destruction of adjacent tissues, and sometimes spread to other locations in the body via lymph or blood. These three malignant properties of cancers differentiate them from harmless, which are self-limited, do not invade or spread. Most cancers form a tumor but some, like leukemia, do not take the form of tumor. It is a different class of diseases, which differ widely in their causes and biology.

People at all ages, even fetuses, may be affected by cancer but risk for the more common varieties tends to increase with age. Not only humans are affected by cancer but also there are even some form of cancer that even attacks plants and animals both. Near about all cancers are caused by abnormalities in the genetic material of the transformed cells and this may be due to the effects of carcinogens, such as tobacco smoke, asbestos inhalation, chemicals, radiation or infectious agents. There are also other cancer-encouraging genetic abnormalities that may arise through errors in DNA replication, or are acquired from birth.

Why only some is then develops cancer after exposure to a known carcinogen while other remains safe? This happens due to the complex interactions between carcinogens and the host genome. A pathologist usually classifies Cancer according to the tissue from which the cancerous cells originate, and a standard diagnosis usually requires the histological scrutiny of a tissue biopsy specimen. Although most cancers are initially recognized either looking at the symptoms that appear or through screening but neither of these lead to a definitive diagnosis. Biopsy is considered as the standard form of diagnosis. Depending on the specific type, location, and stage, most cancers can be treated and some cured usually with a combination of surgery, chemotherapy and radiotherapy.

Among the most common cancers worldwide are due to nine potentially modifiable risk factors that includes tobacco smoking, excessive alcohol use, diet low in fruits and vegetables, lack of physical exercise, unsafe sex, urban air pollution, domestic use of solid fuels, and contaminated injections like hepatitis B and C. Men are twice more vulnerable than women to have a modifiable risk factor for their disease. Cancer can be prevented by avoiding carcinogens or altering their metabolism, pursuing a lifestyle or diet that modifies cancer-causing factors and/or medical intervention for instance chemoprevention, treatment of pre-malignant wounds.

Description:
Cancer is a different class of diseases, which differ widely in their causes and biology and are also treated accordingly.