Anything that increases a person's risk for contracting a disease is called a risk factor. Unlike other forms of cancer, CLL has few known risk factors.
Although people with CLL are more likely than others to have a family member with CLL or with another type of lymphoma, it is not an inherited disease. Most people who have a relative with CLL will never have CLL themselves.
Some studies suggest that certain environmental factors might play a role in the development of CLL, including exposure to some chemicals (herbicides and insecticides).
Monoclonal B-cell lymphocytosis (MBL) is diagnosed when patients have a small number of cells with the characteristics of CLL cells in their blood and do not have any CLL symptoms or signs of lymph node, spleen or liver enlargement. A small percentage of these patients will go on to develop CLL.
It is important to remember that even if you have one or more risk factors, you will not necessarily develop CLL. In fact, most people with risk factors never develop the disease and many who are diagnosed have no known risk factors.