Cancer can arise from a single cell that begins to grow and divide uncontrollably, eventually forming a mass of cells known as a tumor. A tumor (even a benign tumor) can interfere with the function of the organ in which it is growing. When a tumor is able to spread beyond its original site and invade neighboring tissues, the tumor is considered to be cancerous.

The Stages of Cancer

Cancer staging is the process of evaluating a person with cancer to determine how far the disease has advanced. Features such as the size of the primary tumor and how far it has spread into neighboring tissues and lymph nodes help determine which stage level is assigned. In the most commonly used staging classification system (called the TNM system), cancers are given a classification of stage 0 through stage 5, with stage 5 being the most advanced state of disease.

The early signs of cancer can vary greatly, depending on the tissue in which the tumor is located. Prognosis and treatment also depend on the site of the tumor as well as the stage of the disease. Explore our cancer articles for information on individual types and signs of cancer, some of which are highlighted below.

Cancers of the Blood: Lymphoma and Leukemia

Lymphoma (cancer of the lymphatic system) and leukemia (cancer of the tissues that make blood) both have many sub-types that vary in:

  • Diagnosis techniques
  • Prognosis
  • Symptoms.

Explore the collection of articles on lymphoma cancer and leukemia cancer to understand the differences between the various kinds of blood-associated cancers.

Cancers of the Respiratory System: Lung Cancer and Mesothelioma

Mesothelioma cancer affects the mesothelium (the layer of cells that surrounds many organs). Although it can originate in many different locations, the lungs are the most common site of mesothelioma. Cancer that originates in the cells of the lung itself is known as lung cancer. For both mesothelioma and lung cancer, signs commonly include chronic coughing and chest pain. Browse the articles on to learn about these diseases of the respiratory system.

Gynecologic Cancers: Cervical and Ovarian Cancer

Gynecologic cancers affect tens of thousands of women in the United States each year. They include any cancer that begins in the female reproductive organs, such as cervical cancer (one of the most common) and ovarian cancer (one of the most deadly).