What is Follicular lymphoma

Follicular Lymphoma is cancer of the lymphatic system. There are two broad categories of lymphoma: Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. Follicular lymphoma is a type of non-Hodgkin’s lymphoma.
Lymphatic system is an important part of our immune system that helps fight infection. It is composed of various organs e.g. lymph nodes, thymus, spleen and bone marrow. These are connected by a network of tiny lymphatic vessels.
Lymph is a colourless fluid that circulates in the lymphatic system. It contains lymphocytes, which are white blood cells that fight infection. There are 2 types of lymphocytes: B cells and T cells. Follicular lymphoma is a cancer of B cells. It is called follicular lymphoma because the malignant cells usually grow in a circular or follicular pattern in the lymph nodes.

Statistics on Follicular lymphoma

Follicular lymphoma is one of the commenest types of lymphoma in Western countries. Follicular lymphoma accounts for 20-30% of all lymphomas. Follicular lymphoma is the most common type of slow-growing or indolent non-Hodgkin’s lymphoma.
Variations in racial incidence are found. The incidence of follicular lymphomas is low in China and Japan. People of Jewish ancestry have a higher incidence.
The incidence of follicular lymphomas increases with age. Most patients are around 60 years old when the disease is diagnosed. Follicular lymphomas are extremely rare in children. The ratio of male to female affected is about 2:3.

Risk Factors for Follicular lymphoma

Age: Middle-aged and elderly people.
Gender: Slightly more common in female.
Ethnicity: Less common in the Asian and African American populations.
There are changes in the gene involving transfer of part of the gene to a different location, called t(14;18) gene translocation, which results in overexpression of a protein BCL-2.

Progression of Follicular lymphoma

When follicular lymphoma is diagnosed, it is mostly already at an advanced stage.
Follicular lymphoma patients usually come with widespread enlargement of the lymph nodes in multiple parts of the body.
World Health Organization (WHO) classifies follicular lymphoma into three different grades, according to the number of large cells they contain:
 

  • Grade I, or small-cleaved cell type: a person has fewer than five large cells per high power field under the microscope.
  • Grade II, or mixed small-cleaved and large cell type: a person has between 6 and 15 large cells per high power field under the microscope.
  • Grade III, or large cell type: a person has more than 15 large cells per high power field.Grade I is the most common type. Grades I and II are generally considered to be indolent, or slow-growing. Grade III follicular lymphoma is more fast-growing, and requires aggressive treatment.Follicular lymphoma can become more aggressive over many years, and the follicular pattern may change from a lower percentage of large cells to primarily large cells.

    How is Follicular lymphoma Diagnosed?

    Bloods will be taken to be looked under the microscope for the number of blood cells, the level of the enzyme lactate dehydrogenase for evaluation of tissue damage (which, if high, indicates a worse prognosis).

    Prognosis of Follicular lymphoma

    Although most follicular lymphoma patients present at an advanced stage, the prognosis of follicular lymphoma is better than that of many higher grade lymphomas.
    The average survival is 10 years. 72% of follicular lymphoma patients survive for 5 years after the initial diagnosis.
    Factors that predict a worse prognosis are:
     

  • Age >60 years
  • Advanced clinical stages
  • Low haemoglobin level
  • More than 4 involved nodal areas
  • High level of an enzyme called lactate dehydrogenase

    How is Follicular lymphoma Treated?

    Follicular lymphoma responds well to chemotherapy and radiotherapy.
    Follicular lymphoma patients with early-stage disease may be treated with local radiation, with or without chemotherapy.
    Follicular lymphoma patients, especially older patients, with more advanced but low-grade disease may remain untreated as long as there are no symptoms or organ damage associated with the lymphoma (watch and wait).
    When treatment of follicular lymphoma becomes necessary, chemotherapy is given using either a single agent (e.g. chlorambucil or cyclophosphamide) or combination chemotherapy.
    With adequate treatment, follicular lymphoma will be abated in 50 to 75% of patients. While follicular lymphoma comes back in most patients (on average after 2 years), at least 20% of those who respond will remain free of the disease for more than 10 years.
    There are new therapies increasingly used, e.g. cytotocis agents, biologic agents, monoclonal antibodies e.g. rituximab.
    In follicular lymphoma that recurs, stem cell tranplantation results in good response.

    Follicular lymphoma References

    [1] Braunwald E et al. Harrison’s principles of internal medicine. 15th ed. New York; McGraw-Hill; 2001.
    [2] Freedman AS. Patient information: Follicular lymphoma [online]. 2005 [cited 2005 August 26th]. Available from: URL: http://patients.uptodate.com/topic.asp?file=blod_dis/7201
    [3] Souhaimi et al, editors. Oxford Textbook of Oncology. 2nd ed. Oxford ; New York : Oxford University Press; 2002.