Cancer is one of the leading causes of death in developed countries

Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion or by implantation into distant sites by metastasis. This unregulated growth is caused by damage to DNA, resulting in mutations to genes that control cell division. Several mutations may be required to transform a normal cell into a malignant cell. These mutations are often caused by chemicals or physical agents called carcinogens. Some mutations occur spontaneously, or they can be inherited as germ line mutations.

Cancer can cause many different symptoms, depending on the site and character of the malignancy and whether there is metastasis. Cancer may be painless. A definitive diagnosis usually requires the histologic examination of tissue by a pathologist. This tissue is obtained by biopsy or surgery. Once diagnosed, cancer is usually treated with surgery, chemotherapy, or radiotherapy.

If untreated, cancers may eventually cause death. Cancer is mainly a disease of later years, and is one of the leading causes of death in developed countries. Most cancers can be treated and many cured, especially if treatment begins early. Many forms of cancer are associated with exposure to environmental factors, such as tobacco smoking, alcohol, and certain viruses. Some of these can be avoidable, and public health and vaccination programmes are important on a global scale.

More: en.wikipedia.org/wiki/Cancer

Multiple Sclerosis is a chronic disease

Multiple sclerosis (MS) is a chronic disease that affects the brain and spinal cord. MS can cause a variety of symptoms, including changes in sensation, visual problems, muscle weakness, depression, and difficulties with coordination and speech. Although many patients lead full and rewarding lives, MS can cause impaired mobility and disability in the more severe cases.

Multiple sclerosis affects neurons, the cells of the brain and spinal cord that carry information, create thought and perception and allow the brain to control the body. Surrounding and protecting these neurons is a fatty layer known as the myelin sheath, which helps neurons carry electrical signals. MS causes gradual destruction of myelin (demyelination) and transection of neuron axons in patches throughout the brain and spinal cord, causing various symptoms depending upon which signals are interrupted. The name multiple sclerosis refers to the multiple scars (or scleroses) on the myelin sheaths. It is thought that MS results from attacks by an individual’s immune system on the nervous system and is therefore categorized as an autoimmune disease.

Multiple sclerosis may take several different forms, with new symptoms occurring in discrete attacks or slowly accruing over time. Between attacks, symptoms may resolve completely, but permanent neurologic problems often persist. Although much is known about how MS causes damage, its exact cause remains unknown. MS currently does not have a cure, though several treatments are available which may slow the appearance of new symptoms. MS primarily affects adults, with an age of onset typically between 20 and 40 years, and is more common in women than in men.

More: en.wikipedia.org/wiki/Multiple_sclerosis