Follicular lymphoma, a rare blood cancer of the lymphatic system, is one type of non-Hodgkin lymphoma (NHL). Follicular lymphoma is considered an indolent (low-grade) type of cancer, which means it tends to be nonaggressive and grows slowly. Follicular lymphoma is not yet considered curable with standard therapy, but because it is slow growing and usually appears in older people, it is often managed as a relapsing chronic illness.
Follicular lymphoma is a cancer of the B cells (also known as B lymphocytes), a type of white blood cell that’s part of the immune system. B cells produce antibodies, proteins that help protect us against threats like bacteria and viruses. In B-cell lymphomas such as follicular lymphoma, the bone marrow overproduces abnormal B cells that have lost their ability to fight infection.
To learn more about follicular lymphoma, MyLymphomaTeam spoke with Dr. Timothy Fenske. Dr. Fenske is a hematologist and medical oncologist who specializes in lymphoma at Froedtert & Medical College of Wisconsin in Milwaukee.
“One of the biggest challenges for people with follicular lymphoma is understanding this idea that it’s a slow-growing process, and we have some flexibility in terms of how we might approach it,” Dr. Fenske said. “In many cases, we are able to effectively manage follicular lymphoma, such that the patient still achieves a normal lifespan.”
Follicular lymphoma is a rare disease. Approximately 15,000 to 20,000 new cases are diagnosed each year in the United States. Women and men are both affected by follicular lymphoma, although the disease is slightly more common among women, according to the National Association for Rare Disorders (NORD). The average age of diagnosis is 65. Follicular lymphoma accounts for 20 percent to 30 percent of NHL cases. Follicular lymphoma occurs throughout the world and affects people of all races, although people of Asian and African descent have a slightly lower rate of the disease.
There are many subtypes of follicular lymphoma, including:
Dr. Fenske explained that because follicular lymphoma is a slow-growing indolent cancer, the disease may be discovered during routine blood work or tests for other conditions, before someone experiences symptoms of follicular lymphoma itself. “In many cases, the patient may be in their 60s, 70s, or 80s, and we incidentally diagnosed them with follicular lymphoma. They may not really have symptoms, and it’s not really affecting them,” he said.
The most common symptom of follicular lymphoma is painless swelling in the neck, armpits, or groin. This swelling is caused by enlarged lymph nodes due to B cells clumping into tumors in different parts of the body. Less common follicular lymphoma symptoms include:
Between 40 percent and 70 percent of all people with follicular lymphoma have follicular lymphoma cells in bone marrow. In about 50 percent of follicular lymphoma cases, the spleen is affected and causes splenomegaly (enlargement of the spleen). Abnormal blood counts can be an indication of follicular lymphoma in bone marrow or the spleen. Symptoms include:
Medical researchers don’t fully understand why some people develop follicular lymphoma. Genetic changes (also known as mutations) in B cells are believed to cause approximately 85 percent of cases, according to NORD. However, follicular lymphoma isn’t inherited. The gene mutations associated with follicular lymphoma happen over time.
Environmental factors, such as exposure to toxic chemicals, smoking and exposure to tobacco smoke, and some types of infections may contribute to the development of follicular lymphoma.
One of the challenges in diagnosing follicular lymphoma is that swollen lymph nodes can be a symptom of many other diseases. “When people get lymphoma, the symptoms can often mimic other conditions, like inflammatory conditions or autoimmune diseases. It can be tricky sometimes to get that diagnosis sorted out,” said Dr. Fenske.
In fact, dozens of other conditions have symptoms similar to lymphoma. These include common illnesses, like colds, influenza, and sinus infections, along with more serious diseases like AIDS, breast cancer, and the fungal infection histoplasmosis.
Follicular lymphoma is diagnosed through a lymph node biopsy, which collects B cells using a needle. The cells are then examined under a microscope. Alternatively, an entire lymph node may need to be removed for a biopsy, a procedure that can be performed under local anesthesia.
As Dr. Fenske explained, a diagnosis may take time. “Once a person does have a biopsy, being able to say with certainty that ‘Yes, in fact, this is lymphoma, and this is the exact type’ can also be tricky,” he said. “Sometimes you need a pathologist who really has a lot of experience diagnosing lymphomas to really pin that down. It’s never a bad idea to get a second opinion on the pathology reading.”
You may be given additional blood tests to check your kidney and liver function and make sure you’re healthy enough to receive treatment.
The Ann Arbor staging system is often used to diagnose the stages and progression of follicular lymphoma. Stages include:
Each stage also includes the letter A or B to indicate absence or presence of symptoms, respectively.
Most people with follicular lymphoma aren’t diagnosed until the disease has progressed to advanced stage 3 or stage 4. Less than 20 percent of people with early stage 1 or stage 2 follicular lymphoma are diagnosed, due to a lack of obvious symptoms.
Doctors most commonly use the Follicular Lymphoma International Prognostic Index (FLIPI) to predict potential outcomes and decide how aggressively to treat a case of follicular lymphoma. Five risk factors receive a score of one point each, including whether a person:
A FLIPI score of zero or 1 indicates a low-risk case. A score of 2 indicates medium risk, and a score of 3 or more indicates high risk of more aggressive disease.
Doctors also look at how fast cancer cells are growing and assign a grade of 1, 2, 3A, or 3B. Grade 3B indicates fast-growing follicular lymphoma. A pathologist will determine the grade when analyzing a biopsy.
Many people with follicular lymphoma may not need treatment for many years. As Dr. Fenske explained, “More indolent or low-grade lymphomas like follicular lymphoma are slow growing and actually don’t even always require treatment.”
At the same time, a number of effective treatment options are available for people with more advanced symptoms of follicular lymphoma.
Active monitoring — also called watchful waiting or “watch and wait” — tracks asymptomatic or low-symptomatic follicular lymphoma cases with regular checkups and evaluations, such as blood tests and CT scans. Watchful waiting is often the approach with new cases of follicular lymphoma or cases in remission (a period of reduced or no symptoms) after treatment. Studies show that for people with follicular lymphoma who don’t have advanced symptoms, active monitoring has the same survival rate as treatment.
“People have a really hard time sometimes wrapping their head around that idea,” Dr. Fenske said. “’OK, you’re telling me I have cancer. And then in the next sentence, you’re telling me we’re not going to do anything about it.’ This can be difficult for patients to accept, especially when they are initially diagnosed and scared. But [follicular lymphoma] can be so slow-moving that, in some cases, five or more years later, the person still hasn’t required treatment.”
When someone with follicular lymphoma is first diagnosed and has few or no symptoms, Dr. Fenske carefully watches how the condition is progressing. “Usually I will see them back in about three months. And somewhere between three and six months after the initial diagnosis, I will typically get another CT scan to get a feel for how these lymph nodes are changing,” he explained.
“If they’ve increased significantly in a matter of a few months, that’s somebody that we’re probably going to need to treat,” he said. “Other times, they really have not changed at all six months later, 12 months later, two years later. Sometimes they even regress somewhat on their own.”
In early-stage follicular lymphoma cases that require treatment, low-dose radiation therapy is considered highly effective and may result in long-term remission. Some studies indicate that very low-dose radiation therapy can be effective for more advanced stages of follicular lymphoma, while at the same time shortening the course of treatment and reducing side effects.
Radiation therapy for non-Hodgkin lymphomas, such as follicular lymphoma, involves a tightly focused beam of radiation aimed at the affected area from outside the body. Treatments are typically scheduled five days a week over the course of several weeks.
Chemotherapy and monoclonal antibodies are drug therapies used to treat follicular lymphoma. Regimens often consist of a combination of drugs, such as:
For follicular lymphoma cases that don’t respond well to other treatments, bone marrow transplants may be recommended. There are two main types of bone marrow transplants:
Because of the risks associated with bone marrow transplantation, the treatment may not be recommended for some people with follicular lymphoma.
Immunotherapies harness the power of your immune system to fight cancer. There are several types of immunotherapies, including chimeric antigen receptor (CAR) T-cell therapy and bispecific T-cell engagers.
CAR T-cell therapy is a promising new treatment for follicular lymphoma and other blood cancers. The treatment uses T cells — a type of white blood cell that attacks and kills unhealthy cells — from the person’s own blood. These cells are then genetically modified in a laboratory to produce chimeric antigen receptors that can attack cancer cells.
This type of targeted therapy has been shown to produce a complete remission rate of up to 90 percent in some forms of blood cancer. CAR T-cell therapy drugs approved by the U.S. Food and Drug Administration (FDA) for follicular lymphoma include:
Bispecific T-cell engagers (BiTEs) are another newer category of immunotherapy for follicular lymphoma. BiTEs combine a monoclonal antibody, or synthetic immune protein, with a drug that kills cancer cells. The monoclonal antibody targets lymphoma cells to deliver the drug. Bispecific T-cell engagers approved to treat follicular lymphoma in some cases include:
Another newer class of drugs that is used to treat follicular lymphoma are kinase inhibitors, another type of targeted therapy. Kinase inhibitors target and block enzymes in cells that are linked to cancer. These drugs are used for relapsing or refractory follicular lymphoma, when other treatments have not been effective, and include:
A relapse occurs when treatment that was effective stops working and follicular lymphoma returns. Symptoms of relapsing follicular lymphoma are often similar to symptoms when the disease is first diagnosed, including:
About 20 percent of people with follicular lymphoma relapse within two years after first undergoing treatment. Many people may go into remission — and be symptom-free — for many years. But for most people, follicular lymphoma will eventually return. People with follicular lymphoma who relapse within 24 months of treatment are more likely to have a poor outcome.
When someone doesn’t respond to a first course of treatment, the condition is known as refractory follicular lymphoma.
Read about treatment options for relapsed or refractory follicular lymphoma.
Advances in both diagnosis and treatment have raised the overall survival rate for people with follicular lymphoma. A recent oncology study of 1,088 people with follicular lymphoma showed an overall survival rate of 92 percent at five years, 80 percent at 10 years, and 65 percent at 15 years. This is a big improvement from the 1960s through the 1980s, when the survival rate was about 50 percent at 10 years. The American Cancer Society estimates an overall survival rate of 90 percent at five years for people with follicular lymphoma.
MyLymphomaTeam asked Dr. Fenske that important question.
“In the last few years, we’ve gotten into CAR-T cell therapy,” replied Dr. Fenske, who is involved in clinical trials using this treatment. “Most resources that you read about follicular lymphoma will say that it is not considered curable. But I would qualify that by saying that it’s not routinely curable with conventional therapy. Data for CAR T-cell therapy in follicular lymphoma is just emerging now, so we don’t really know what the long-term outcomes are going to look like.”
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