The International Retinoblastoma Staging System (IRSS) may be used for staging retinoblastoma.
There are several staging systems for retinoblastoma. The IRSS stages are based on how much cancer remains after surgery to remove the tumor and whether the cancer has spread.
The eye has not been removed and the tumor was treated without surgery.
The eye has been removed and no cancer cells are seen.
The eye has been removed and there are cancer cells left that can be seen only with a microscope.
Stage III is divided into stages IIIa and IIIb:
- In stage IIIa, cancer has spread to tissues around the eye socket.
- In stage IIIb, cancer has spread to lymph nodes near the ear or in the neck.
Stage IV is divided into stages IVa and IVb:
- In stage IVa, cancer has spread to the blood but not to the brain or spinal cord. There are one or more tumors.
- In stage IVb, cancer has spread to the brain or spinal cord. It may have spread to other parts of the body as well.
Treatment for retinoblastoma depends on whether it is intraocular (within the eye) or extraocular (outside the eye).
In intraocular retinoblastoma, cancer is found in the eye and may be only in the retina or may also be in other parts of the eye such as the choroid, ciliary body, or part of the optic nerve. Cancer has not spread to tissues around the outside of the eye or to other parts of the body.
Extraocular retinoblastoma (metastatic)
In extraocular retinoblastoma, cancer has spread beyond the eye. It may be found in tissues around the eye (orbital retinoblastoma) or it may have spread to the central nervous system (brain and spinal cord) or to other parts of the body such as the bone marrow or lymph nodes.
There are three ways that cancer spreads in the body.
Cancer can spread through tissue, the lymph system, and the blood:
- Tissue. The cancer spreads from where it began by growing into nearby areas.
- Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.
- Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.