TNM Staging System

Staging is the process of finding out how much cancer there is in a persons body and where its located. Its how the doctor learns the stage of a persons cancer.

Doctors use staging information to plan treatment and to help predict a persons outlook (prognosis). Cancers with the same stage tend to have similar outlooks and are often treated the same way. The cancer stage is also a way for doctors to describe the extent of the cancer when they talk with each other about a persons cancer.

Why is staging needed

Doctors need to know the amount of cancer and where it is in the body to be able to choose the best possible treatment. For example, the treatment for early stage breast cancer may be surgery and radiation, while a more advanced stage of breast cancer may need to be treated with chemotherapy, too. Doctors also use the stage to help predict the course a cancer will likely take.

In a larger sense, doctors use staging information when they compare cancer treatments. It allows researchers to make sure study groups are actually similar when they test cancer treatments against one another, measure outcomes, and more.

What is the doctor looking for when staging cancer

Doctors look for the primary cancer (the original tumor) and also check for other tumors. They will look at the size, number, and location of any tumors, to see if the cancer has spread far away.

Doctors also look at nearby lymph nodes, to find out if cancer has spread into them. Lymph nodes are small bean-shaped collections of immune system tissue found along lymphatic vessels. They remove cell waste, germs, and other harmful substances from lymph. They help fight infections and also have a role in fighting cancer, but cancers can spread through them.

In some kinds of cancer, cancer cell type and grade (as seen under a microscope) become part of the stage.

How are cancers staged Doctors gather different types of information about a cancer to figure out its stage. Depending on where the cancer is located, the physical exam may give some clue as to how much cancer there is. Imaging tests like x-rays, CT scans, MRIs, ultrasound, and PET scans may also give information about how much and where cancer is in the body.

Often, biopsy is needed to confirm the diagnosis of cancer. Biopsies are also needed to find out if an abnormal spot on an imaging test is really cancer spread. A biopsy involves taking out tumors or pieces of tumors and looking at them under the microscope. Some biopsies may be done during surgery. But many types of biopsies are done by removing small pieces of tumor through a thin needle or through a flexible lighted tube called an endoscope. The different kinds of biopsies used to check for cancer are described in our Surgery document.