Lymphomas grow as the result of something that causes changes in the cell genes or DNA. This change in the genes interferes with cell division and cell death.
Some people are more at risk of lymphoma. This is usually because of another medical condition, in particular medical conditions that interfere with the immune system or where the immune system is artificially suppressed. Doctors also know that certain lymphomas grow as a result of particular viral infections. These account for a very small proportion of cases.
In most cases, the cause of lymphoma is not known. There have been lots of research studies to suggest possible connections, such as chemicals present in the working environment or increased risk of lymphoma in some families. But it will be a long time before scientists understand this subject properly.
There is no evidence to suggest that anything you have done - or not done - has caused you to develop lymphoma. You can't catch lymphoma from someone, and you can't give it to anyone else.
You can read more about the causes of lymphoma by clicking here
