Cancer is a class of diseases where a group of cells display uncontrolled growth. Cells are aggressive, invasive and metastatic. These malignant properties of cancer differentiate it from being tumors which are limited in their growth.

1. Breast cancer

This disease occurs when cells that are abnormal grow out of control in one or both breasts. They can also invade nearby tissues and form a mass (malignant tumor). In 2005, it caused 502,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths. IT is about 100 times as frequent among women as among men. More than 80% of breast cancer cases are discovered when the woman feels a lump. Indications of it other than a lump may include changes in breast size or shape, skin dimpling, nipple inversion, or spontaneous single-nipple discharge.

2. Lung Cancer

This occurs when abnormal cells grow out of control in the lung.They can form tumors and invade nearby tissue. It is the leading cause of all cancer deaths in men and second most common in women. It is responsible for 1.3 million deaths worldwide annually. The main cause of lung cancer is of course smoking but being exposed to asbestos, arsenic, radioactive dust, or radon can increase your chances of getting lung cancer. Early lung cancer unfortunately does not have any symptoms but in advanced stages this disease may effect how the lungs are working. The first signs and symptoms of it are: shortness of breath, coughing (including coughing up blood), and weight loss. It may spread to the chest and then to other parts of the body.

3. Colorectal cancer (colon cancer)

This occurs when cells that are abnormal grow in your colon or rectum. These cells grow together and form tumors. With 655,000 deaths over the world per year, it is the third most frequent types of cancer and the second leading cause of cancer-related death in the Western world. When it is found early then it is easily treated and often cured. But usually it is not found early and that is why it is so high in the list. Fairly simple screening tests can prevent this disease, but fewer than half of people older than 50 are screened. The symptoms of it are usually vague, like bleeding, weight loss, and fatigue. Local (bowel) symptoms are rare until the tumor has grown to a large size.

4. Prostate cancer

This is a disease in which cancer develops in the prostate, a gland in the male reproductive system. The prostate sits just below the bladder. In young men, the prostate is about the size of a walnut. It usually grows larger as you grow older. This disease may cause pain, difficulty in urinating, problems during sexual intercourse, erectile dysfunction and other symptoms. It develops most frequently in men over fifty. This cancer can occur only in men, as the prostate is exclusively of the male reproductive tract.