How is Cancer Diagnosed?

For some, cancer is found through routine screening tests. For many, cancer does not cause problems until it has progressed enough to cause symptoms. Some people notice unusual pain, fatigue, fever, or weight loss. Others experience shortness of breath, drenching night sweats, or develop a suspicious lump. In most cases, cancer is a suspect because of the combination of symptoms that may be brought on by a number of different diseases.

Physicians generally perform a series of special blood tests and imaging procedures (such as PET or CT scans) to determine if cancer does exist and the extent to which it may have spread. Usually cells are removed from the area of disease so that they can be viewed closely under a microscope.

Removal of tissues for microscopic review is called a biopsy. Depending on the type of cancer, a biopsy procedure may occur via surgery, blood testing, needle aspiration, or tissue scraping. Biopsy specimens are reviewed by specialized physicians known as pathologists. The pathology report describes the cell type, whether the cells are normal or abnormal, and the degree and scope of abnormality.

When cells are found to be abnormal, or malignant, then a specific cancer diagnosis is made by the pathologist and reported to your doctor in a pathology report. With a surgical procedure, the pathologist will also look at the tissue that was removed to see if the margins (outer edges) contain cancer cells. If cancer cells are seen at the edges of the tissue, the margins are called "positive." Positive margins can mean that some cancer was left behind. When no cancer is seen at the edges of the tissue, the margins are said to be "negative," "clean," or "clear."

Staging is the process of finding out how much cancer is in the body, where it is located, and if it has spread. Doctors use staging information to plan treatment and to help determine a person's prognosis, or outlook for survival. Cancers of the same type, diagnosed at the same stage, usually have a similar prognosis and are often treated the same way.

There are several different staging systems. Each system is somewhat specific to individual types of cancer. The TNM staging system (Tumor, Node, Metastasis) is the most common system, and it describes the extent of the primary (main) tumor, whether nearby lymph nodes contain cancer cells, and if metastatic disease is present.