What are the Grades and Stages of Non-muscle Invasive Bladder Cancer?

Grade and stage are two important ways to measure and describe how cancer develops. A tumor grade tells how aggressive the cancer cells are. A tumor stage tells how much the cancer has spread.

Tumor Grade

Grading is one of the ways to know if the disease will come back. It also tells us how quickly the cancer may grow and/or spread.

Tumors can be low or high grade. High-grade tumor cells are very abnormal, poorly organized and tend to be more serious. They are the most aggressive type.

Tumor Stage

The tumor stage tells how much of the tissue has the cancer. Doctors can tell the grade and stage of bladder cancer by taking a small sample of the tumor. This is called a biopsy. A pathologist in a lab examines the sample under a microscope and determines the grade and stage of the cancer.

The stages of bladder cancer are:

  • Ta: Tumor on the bladder lining that does not enter any layers of the bladder
  • Tis: Carcinoma in situ (CIS)-A high-grade cancer but "flat" cancer. It looks like a reddish, velvety patch on the bladder lining
  • T1: Tumor goes through the bladder lining, into the second layer, but does not reach the muscle layer 
  • T2 : Tumor grows into the muscle layer of the bladder
  • T3: Tumor goes past the muscle layer into tissue surrounding the bladder, usually fat surrounding the bladder
  • T4: Tumor has spread to nearby structures of the bladder such as the prostate in men or the vagina in females

What Does NMIBC Look Like?

Bladder cancer   is described by how far into the wall of the bladder the cancer has grown (which is the clinical stage). Non-muscle invasive bladder cancers are found in the inner layer cells of the bladder. These cancers do not invade the muscular wall. These tumors are staged from Ta (lowest stage) to T1 (highest stage for NMIBC).

Over half of patients with low-grade Ta cancers will have a tumor recurrence. About 6% will progress to a higher stage. High-grade T1 cancers recur at a rate of about 45% and 17% of these will probably progress to a higher stage.

Once diagnosed, the rates of survival are quite favorable for patients with NMIBC. Survival in high-grade disease ranges from about 70-85% at 10 years and a much higher rate for low-grade disease. However, it is important that the disease is diagnosed early. This helps doctors predict the course of the disease and choose the best treatment to stop it from growing.