Grading eye cancer

Grading describes how the cancer cells look compared to normal, healthy cells. Knowing the grade gives your healthcare team an idea of how quickly the cancer may be growing and how likely it is to spread.

For many types of cancer, the grade can help the healthcare team plan treatment. But the grade is rarely used to help plan treatment for eye cancer. This is because doctors need to remove a sample of tissue from the eye to find out the grade. But removing tissue from the eye can cause damage. Instead, your healthcare team will plan treatment based on the results of other tests such as an eye exam and imaging tests. Grading isn’t done unless you have a biopsy or surgery to remove tissue from the eye.

If grading is done, a pathologist looks at a sample of tissue from the eye to see how different the tumour cells look from normal cells (called differentiation) . They will also look at other features of the tumour, such as the types, size and shape of the cells, how the cells are arranged and if they’ve spread to nearby structures. The pathologist can usually tell how fast a tumour is growing by looking at how many cells are dividing.

The pathologist uses this information to give the cancer a grade. A lower number means the cancer is a lower grade. Low-grade cancers tend to grow slowly and are less likely to spread. High-grade cancers tend to grow more quickly and are more likely to spread.

Uveal melanoma is given a grade from 0 to 3. Low-grade uveal melanoma is mainly made up of spindle cells. High-grade uveal melanoma is mostly made up of epithelioid cells.

Conjunctival squamous cell carcinoma (SCC) or orbital adnexal lymphoma is given a grade from 0 to 4. Low-grade cancers have cancer cells that are well differentiated. The cells are abnormal but look a lot like normal cells and are arranged a lot like normal cells. High-grade cancers have cancer cells that are poorly differentiated or undifferentiated. The cells don’t look like normal cells and are arranged very differently.

Other types of eye cancer may be graded differently or may not be given a grade at all.

Find out more about grading cancer.