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 examine 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
Another grading system describes bladder cancer as either low grade or high grade.
From the number grades, grade 1 is low grade and Grade 3 is high grade. Grade 2 can be split into either low or high grade. Carcinoma in situ (CIS) tumours are high grade.
If you have early (superficial) bladder cancer but the cells are high grade, you are more likely to need further treatment. This is to stop the cancer coming back after it has been removed.
World Health Organisation (WHO) grades
A third grading system is sometimes used for early bladder cancer. This system divides bladder cancers into four 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 cancer 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