He died of cancer of the lymph system, his family said.
The cancer may come back in the lymph system or in other parts of the body.
Two years ago, he underwent treatment for cancer of the lymph system that was considered successful.
The lymph system plays a major role in the body's immune defenses against infection.
The process used to find out if cancer has spread within the lymph system or to other parts of the body is called staging.
Among the areas he has studied are breast cancer and cancers of the lymph system.
Cancer cells usually spread through the bloodstream or the lymph system.
This is necessary because cancer can spread through the lymph system to other areas of the body.
It can spread to other parts of the body through the lymph system and the blood.
Already, the Columbia team has linked the virus to a rare cancer of the lymph system.