The grade of a cancer means how much the cancer cells look like normal cells. It tells your doctor how the cancer might behave and what treatment you need.
To find the grade of cancer cells, doctors take tissue samples (biopsies) and send them to the laboratory. A specialist (pathologist) looks at them using a microscope.
Bladder cancer cells are divided into 3 grades.
The cancers cells look very like normal cells. They are called low grade or well differentiated. They tend to grow slowly and generally stay in the lining of the bladder.
The cancer cells look less like normal cells (abnormal). They are called moderately differentiated. They are more likely to spread into the deeper (muscle) layer of the bladder or to come back after treatment.
The cancer cells look very abnormal. They are called high grade or poorly differentiated. They grow more quickly and are more likely to come back after treatment or spread into the deeper (muscle) layer of the bladder.
Low grade and high grade
Bladder cancer can also be described as either low grade or high grade.
Low grade bladder cancer means that your cancer is less likely to grow, spread and come back after treatment. High grade means your cancer is more likely to grow spread and come back after treatment.
For example, if you have early (superficial) bladder cancer but the cells are high grade, you're more likely to need further treatment after surgery. This is to reduce the risk of your cancer coming back.
Low grade is the same as grade 1. High grade is the same as grade 3. Grade 2 can be split into either low or high grade. Carcinoma in situ (CIS) tumours are high grade.
World Health Organisation (WHO) grades
Another grading system sometimes used for early bladder cancer. This divides bladder cancers into 4 groups:
- urothelial papilloma means it is a non cancerous (benign) tumour
- papillary urothelial neoplasm of low malignant potential (PUNLMP) means it is a very slow growing tumour that is unlikely to spread
- low grade papillary urothelial carcinoma is a slow growing cancer that is unlikely to spread
- high grade papillary urothelial carcinoma is a quicker growing cancer that is more likely to spread