A cancer grade measures how quickly a cancer is predicted to progress. Doctors typically divide follicular lymphoma into grades 1 to 3 depending on how the cancer cells look under a microscope.

Follicular lymphoma makes up about 30% of all non-Hodgkin’s lymphomas. It develops in B cells, which are a type of white blood cell that produces antibodies.

The outlook for people with follicular lymphoma is usually good since it typically develops slowly, although some follicular lymphomas are more aggressive than others.

People with follicular lymphoma live at least 5 years after diagnosis about 90% as often as people without cancer.

In this article, we look at how doctors determine grades for follicular lymphoma and how these grades influence treatment.

The World Health Organization (WHO) grading system divides follicular lymphoma into grades 1 to 3 depending on how a sample of cancer cells looks under a microscope. This grading system is based on how many enlarged B cells, called centroblasts, are seen.

Research suggests that having more of these large cells is associated with faster cancer progression and a higher chance your lymphoma will progress into a more aggressive type of non-Hodgkin’s lymphoma called diffuse large B-cell lymphoma.

About 25% to 35% of follicular lymphoma cases progress to this type of lymphoma.

Grade 1 follicular lymphoma is the least aggressive type. It’s also called follicular small cleaved cell lymphoma.

Doctors diagnose grade 1 follicular lymphoma if they see 0 to 5 centroblasts per high power field (HPF). An HPF is usually defined as the area doctors can see under a microscope at 400 times magnification.

Grades 1 and 2 follicular lymphoma are considered slow growing. They are generally treated the same way.

Radiation therapy is the primary treatment for lymphoma isolated to one part of your body. Doctors generally use a type of immunotherapy called anti-CD20 antibodies combined with chemotherapy for advanced and symptomatic follicular lymphoma.

Grade 2 follicular lymphoma is also called follicular mixed-cell lymphoma. It’s defined as follicular lymphoma with 6 to 15 centroblasts per HPF.

Treatment for grade 2 follicular lymphoma is generally the same as grade 1.

Doctors diagnose grade 3 follicular lymphoma, or follicular large cell lymphoma, if they see more than 15 centroblasts per HPF.

The WHO divides grade 3 follicular cancer into two subcategories depending on its features:

Grade 3A

The WHO classifies follicular lymphoma as grade 3A if there are centrocytes present in your cancer sample. Centrocytes are small- to medium-sized B cells that have a cleaved nucleus. A cleaved nucleus is a cell that looks divided under a microscope. It occurs with certain types of lymphomas.

R-CHOP chemotherapy usually treats grade 3A follicular lymphomas if there are aggressive clinical features present, such as:

Treatments for grade 3A follicular lymphomas without aggressive clinical features typically involve radiation of localized disease for stage 1 and rituximab (Rituxan) with or without bendamustine (Treanda) chemotherapy for stages 2 through 4.

These treatments help relieve symptoms associated with low blood counts.

Grade 3B

Doctors diagnose grade 3B follicular lymphoma if the cancer sample looks like a solid sheet of centroblasts.

Research suggests that grade 3B follicular lymphoma follows an aggressive course like diffuse large B cell lymphoma.

Doctors usually treat people with grade 3B follicular lymphoma with aggressive chemotherapy regimens, such as R-CHOP.

Is grade 3 follicular lymphoma curable?

Follicular lymphoma is not usually curable. However, treatment can help slow its progression and reduce your symptoms.

A 2022 study found that chemotherapy can sometimes cure follicular lymphoma.

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Your cancer grade measures how aggressive your cancer is predicted to be. Your stage is a measure of how far your cancer has progressed.

Non-Hodgkin’s lymphoma is usually staged with the Lugano classification. It’s based on an older classification system called the Ann Arbor system. It divides cancer into four stages:

  • Stage 1: The cancer is contained to only one group of lymph nodes or one lymphoid organ, like your tonsils. Or the cancer is only in one area of one organ outside of your lymph system.
  • Stage 2: The cancer has spread to two or more lymph node groups on the same side of your diaphragm. Or the cancer has spread to one group of lymph nodes and one area of a nearby organ. It may also affect other groups of lymph nodes on the same side of your diaphragm.
  • Stage 3: The cancer has spread to lymph nodes above and below your diaphragm. Or the lymphoma is in lymph nodes above your diaphragm and in your spleen.
  • Stage 4: The cancer has spread to at least one organ outside of your lymph system, such as your liver or lungs.

For reporting survival statistics, the National Cancer Institute (NCI) uses a different classification system. Here’s how 5-year relative survival rates vary by stage for follicular lymphoma according to the NCI:

StageApproximate Lugano equivalent5-year relative survival rate
Localizedstage 1 or 297%
Regionalstage 391%
Distantstage 487%
All stagesall stages90%

Factors influencing your outlook

Factors linked to a better outlook in people with non-Hodgkin’s lymphoma include:

  • being below age 60
  • having stage 1 or 2 disease
  • having no lymphoma outside lymph nodes or in only one area outside of lymph nodes
  • having the ability to perform daily activities
  • having standard lactate dehydrogenase levels

The WHO divides follicular lymphoma into three grades depending on how the cancer cells look under a microscope.

Grade 1 and 2 follicular lymphoma is generally slow growing. It can be managed with radiation therapy if it’s detected in the early stages. Grade 3 lymphoma is divided into two categories: grade 3A and 3B.

Stage 3B follicular lymphoma is usually treated with aggressive chemotherapy, like another type of lymphoma called diffuse large B-cell lymphoma. There remains controversy on how to best treat grade 3A lymphoma.