Lymphomas, in general, are defined as a group of malignant tumours originating from lymph nodes or other lymphatic tissues including tonsil, spleen, bone marrow etc. They rarely disseminate through lymphatics and primarily affect organs like the brain, stomach, lungs and the bones. Lymphomas are basically are malignant tumours of the immune system. Lymphomas are broadly divided into Hodgkin's (HL) and Non-Hodgkin's Lymphomas (NHL) and treated as two different entities with unique etiopathogenesis and treatment modalities.
The incidence of lymphomas in India is 0.84-1.39 cases per 100,000 people and is generally considered to be lower than that seen in the west and countries like Japan. 50% of these cases occur in people between ages 20- 40 years and so it is considered to be a disease affecting the younger segment of the population. NHL constitutes at least 90 % of the cases.
However, there are some types of lymphomas like Follicular lymphoma which are more often seen in the elderly - those above the age of 60. Additionally, some like Burkits lymphoma and Lymhoblastic lymphoma are seen predominantly in children. Interestingly Hodgkin's lymphomas have a bimodal peak seen in very young as well as the elderly.
As far as causative factors of lymphomas are considered it is multifactorial including some of viruses and immunodeficiency states. Typically, Epstein Barr virus is considered to be associated with Burkits lymphoma and Hodgkin's lymphoma. Some Bacteriae like H pylori infections are usually associated with MALT lymphomas affecting the stomach. The immunodeficiency state of the patient is also an important factor. For example, Primary CNS lymphoma is seen mostly in patients with HIV infections.
Lymphomas are classified as per the 2016 revision of WHO classification of lymphoid neoplasms. Therefore, lymphomas may be classified based on cell size (large/small), nodal architecture (follicular v/s diffuse), aggressive v/s indolent etc.
The most common NHL diagnosis includes Diffuse Large B Cell Lymphoma (DLBCL), follicular lymphomas, Mantle cell lymphoma etc. Hodgkin's lymphoma classification includes Classical HD and Nodular Lymphocyte Predominant HD. To ascertain the exact subtype of lymphoma is of paramount importance in further staging workup and treatment planning.
Lymphomas present with variable signs and symptoms based on the site involved and extent of the disease. This includes Lymph node swelling, backache, unexplained fever, night sweats and unexplained weight loss. Diagnostic and staging investigations include an intact lymph node biopsy with special lab studies called Immuno histochemistry studies (IHC) and in most cases, bone marrow aspiration and biopsy study. Whole body PET CT scan has become the standard staging investigation in the majority of the lymphomas.
Staging of lymphomas help in ascertaining stages I to IV, based on the involvement of lymph nodes above and below the diaphragm and presence or absence of involvement of bone marrow and organs like liver and lung.
Accurate staging is again mandatory for planning the right type and duration of treatment. Risk stratification scoring using few prognostic factors like age sex are also important.
This also helps in prognosticating the low-risk group whose curative rates are as high as 90 %, to high-risk subsets which require aggressive treatment modalities and the results are typically around 40 %.
Treatment modalities include Conventional Combination Cytotoxic chemotherapy which will kill cancer cells as well as normal cells and newer targeted therapy like Monoclonal Antibodies against CD 20 Antigen known as Rituximab which will target only the cancer cells. Rituximab in combination with CHOP based chemotherapy is the standard of care in DLBCL. Treatment agents and duration depend on age, stage, comorbid conditions of the patient like diabetes, hypertension etc.
Aggressive lymphomas are treated with intensive combination chemotherapy and targeted therapy. Milder therapies are generally used for indolent lymphomas. A majority of lymphomas are curable with current treatment strategies. Usually, an end of treatment whole-body PET scan is done to document the complete disappearance of the disease.
Other novel treatment strategies like stem cell transplantation, Novel Agents Antibody Drug Conjugates like Brentuximab. Immunotherapies like anti PD 1 monoclonal antibodies such as Nivolumab are approved for use in relapsed and refractory lymphomas. Cure is possible in a significant subset of patients whose disease has come back after standard treatment strategies.
In summary, recent advances in diagnostics and treatment strategies in the field of lymphomas have made it one of the highly curable malignancies, thereby providing new hope for patients.
February 4th is being observed as World Cancer Day. The theme for this year is "I am and I will". This is an appropriate time to start spreading awareness of the importance of early diagnosis and screening for cancers. Cancer, if detected early is curable.