Did you know, lymphoma is the fifth and sixth most common cancer for males and females respectively in Singapore, with about 800 new cases in total diagnosed per year!
What is Lymphoma?
Lymphoma is a cancer arising from cells of the lymphatic system, which is part of the body's germ-fighting network. The lymphatic system includes the lymph nodes (lymph glands), spleen, thymus gland and bone marrow.
Lymphoma comprises more than 100 subtypes of two closely related cancers: non-Hodgkin's lymphoma (NHL) and Hodgkin lymphoma.
#1 : Hodgkin Lymphoma
Hodgkin lymphoma typically affects young adults and adolescents. It is now a poster child of modern-day oncology as a large majority of patients and even those with advanced stages of the disease will be cured with conventional chemotherapy.
#2 : Non-Hodgkin's Lymphoma
Non-Hodgkin's lymphoma on the other hand, is far more common and by itself, constitutes numerous other subtypes. These subtypes are based largely on whether the lymphoma cancer cell originates from the B or T-lymphocyte. Non-Hodgkin's lymphoma ranges from indolent (slow growing) to highly aggressive (fast growing).
With the advent of new drug and targeted therapy, the prognosis and cure rates of B-cell lymphomas has improved tremendously. While indolent B-cell lymphomas are still considered incurable, the survivals are now significantly prolonged such that they are more akin to chronic diseases rather than terminal cancers. On the other hand, due to the rarity of T-cell lymphomas and paucity of clinical trials investigating effective drug combinations in the diseases, the prognosis of many patients with T-cell lymphoma still remains poor.
What are the symptoms of Lymphoma?
Common signs and symptoms of lymphoma include enlarged lymph nodes, lethargy, fever, night sweats, poor appetite, weight loss, pain, profound fatigue, itching, and abnormal routine blood tests.
The doctor or physician may feel enlarged lymph nodes during a routine clinical examination, or a computed tomography (CT) or positron emission tomography (PET) scan may show enlarged liver, spleen, or lymph nodes.
How is Lymphoma diagnosed?
The most accurate way to diagnose lymphoma is by obtaining a biopsy of the enlarged or abnormal tissue. A biopsy involves surgically removing a small tissue sample and looking at the specimen under a microscope by the pathologist. Lymphoma can also present in bone marrow, and in some instances, the diagnosis is made by bone marrow biopsy.
Traditional treatment option
Historically, the mainstay of treatment for lymphoma has been with conventional chemotherapy. However, chemotherapy is non-selective in its effect and can cause other bystander healthy cells to be affected and this accounts for the notorious side effects of traditional chemotherapy like hair loss, nausea, diarrhoea, bleeding and infections. As there is a limit to how much chemotherapy the body can receive, autologous stem cell transplantation was developed to allow the body to receive a way higher dose of chemotherapy without permanently damaging the bone marrow. This procedure has remained a standard treatment for patients with relapsed aggressive lymphomas.
Advancements in treatment option
Treatment has since evolved a great deal over the past several years and is tailored to the specific subtype of lymphoma. Some lymphomas require immediate treatment (aggressive) while others can be watched and treatment administered only at the time of disease progression (indolent).
Precision cancer medicine on the other hand, uses targeted drugs and immunotherapy engineered to directly attack lymphoma cells with specific abnormalities with the goal of leaving normal cells largely unharmed.
Here are just some of the therapies that exemplify the advances being made:
- Monoclonal antibodies. These man-made antibodies are designed to attach to CD20, a protein found on many types of B-cells. It is thought to work by attacking targeted cells both directly and together with the body's immune system.
- Antibody drug conjugate (ADC), a type of precision cancer agent that targets specific proteins on the lymphoma cell surface with an antibody. The antibody is in turn attached to a cancer cell killing agent that is then internalized following attachment of the antibody to the cancer cell and this causes the cancer cell to die when the toxic effect of this 'smart bomb' is unleashed.
- Checkpoint inhibitors are a new class of medicines that help the immune system recognize and attack cancer. These drugs block PD-1, a protein that inhibits certain types of immune responses. Their application releases the brakes on the immune system, thereby allowing the body to unleash its own army upon the cancer.
- BCL-2 inhibitors. The BCL-2 protein is over-expressed in some lymphoma cells and it contributes to a cancer cell's survival and resistance to standard chemotherapy. Venetoclax is an agent that binds to the BCL-2 protein, thereby disabling its ability to keep cancer cells alive.
- Bruton tyrosine kinase (BTK) inhibitors are targeted agents that work by inhibiting the enzyme BTK which is needed by the cancer to multiply and spread.
- Bispecific antibodies represent an innovative precision immunotherapy approach that helps the body's immune system target lymphoma cells. These antibodies have two arms; one arm of the drug attaches to a specific protein on the lymphoma cell while the other arm activates immune cells in the patient to kill the lymphoma cell.
- Chimeric Antigen Receptor (CAR) T-cell therapy is a new type of treatment that utilizes a patient's own T immune cells to fight certain types of lymphoma. The T-cells are removed from the patient and engineered to recognize specific proteins found on the surface of cancer cells. The T-cells are then infused back into the patient to fight the lymphoma in the body.
With the above-mentioned innovations and many more other treatment options on the horizon in the fight against lymphoma, the prognosis of patients will continue to get better and conventional chemotherapeutic agents will eventually become obsolete as they get replaced by precision medicine.
This article was contributed by Dr Darryl Lim Ching Wen, AIA Preferred Provider. To request an appointment with Dr Lim, please click here.
1. Singapore Cancer Registry Annual Report 2018: Singapore Cancer Registry 50th Anniversary Monograph 1968-2017