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|Classification and external resources|
|Classification and external resources|
Lymphoma is a group of blood cell tumors that develop from lymphocytes. It is sometimes used to refer to just the cancerous ones rather than all tumors. Symptoms may include: enlarged lymph nodes that are not generally painful, fevers, sweats, itchiness, weight loss, and feeling tired, among others. The sweats are most common at night.
The two main types are Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), with two others, multiple myeloma and immunoproliferative diseases, also included by the World Health Organization (WHO) within the category. Non-Hodgkin lymphoma makes up about 90% of cases and includes a large number of subtypes. Lymphomas are part of the broader group of neoplasms called tumors of the hematopoietic and lymphoid tissues.
Risk factors for HL include: infection with Epstein–Barr virus and having others in the family with the disease. Risk factors for NHL include: autoimmune diseases, HIV/AIDS, infection with human T-lymphotropic virus, eating a large amount of meat and fat, immunosuppressant medications, and some pesticides. They are usually diagnosed by blood, urine, or bone marrow testing. A biopsy of a lymph node may also be useful. Medical imaging then may be done to determine if and where the cancer has spread. This spread can occur to many other organs, including: lungs, liver, and brain.
Treatment may involve some combination of chemotherapy, radiation therapy, targeted therapy, and surgery. In NHL, the blood may become so thick with protein that a procedure called plasmapheresis is needed. Watchful waiting may be appropriate for certain types. Some types are curable. The overall five-year survival rate in the United States for HL is 85%, while that for NHL is 69%. Worldwide, lymphomas developed in 566,000 people in 2012 and caused 305,000 deaths. They make up 3–4% of all cancers, making them as a group the seventh-most common form. In children they are the third most common cancer. They occur more often in the developed world than the developing world.
Lymphoma presents with certain nonspecific symptoms. If symptoms are persistent, lymphoma needs to be excluded medically.
Lymphoma is definitively diagnosed by a lymph node biopsy, meaning a partial or total excision of a lymph node examined under the microscope. This examination reveals histopathological features that may indicate lymphoma. After lymphoma is diagnosed, a variety of tests may be carried out to look for specific features characteristic of different types of lymphoma. These include:
Several classification systems have existed for lymphoma, which use histological and other findings to divide lymphoma into different categories. The classification of lymphoma can affect treatment and prognosis. Classification systems generally classify lymphoma according to:
Hodgkin lymphoma is one of the most commonly known types of lymphoma, and differs from other forms of lymphoma in its prognosis and several pathological characteristics. A division into Hodgkin and non-Hodgkin lymphomas is used in several formal classification systems. A Hodgkin lymphoma is marked by the presence of a type of cell called the Reed–Sternberg cell.
Non-Hodgkin lymphoma is more common than Hodgkin lymphoma. The incidence of non-Hodgkin lymphoma increases with age.
The current accepted definition, the WHO classification published in 2001 and updated in 2008, is the latest classification of lymphoma and is based upon the foundations laid within the "Revised European-American Lymphoma classification" (REAL). This system attempts to group lymphomas by cell type (i.e. the normal cell type that most resembles the tumor) and defining phenotypic, molecular, or cytogenetic characteristics. The three large groups are the B cell, T cell, and natural killer cell tumors. Other less common groups are also recognized. Hodgkin lymphoma, although considered separately within the WHO (and preceding) classifications, is now recognized as being a tumor of, albeit markedly abnormal, lymphocytes of mature B cell lineage.
First proposed in 1982, the Working formulation was a classification of non-Hodgkin lymphoma. It excluded the Hodgkin lymphomas and divided the remaining lymphomas into four grades (low, intermediate, high, and miscellaneous) related to prognosis, with some further subdivisions based on the size and shape of affected cells. This purely histological classification included no information about cell surface markers, or genetics, and it made no distinction between T-cell lymphomas or B-cell lymphomas. It was widely accepted at the time of its publication, but is now obsolete. It is still used by some cancer agencies for compilation of lymphoma statistics and historical rate comparisons.
Of the many forms of lymphoma, some are categorized as indolent (e.g. small lymphocytic lymphoma), compatible with a long life even without treatment, whereas other forms are aggressive (e.g. Burkitt's lymphoma), causing rapid deterioration and death. However, most of the aggressive lymphomas respond well to treatment and are curable. The prognosis, therefore, depends on the correct diagnosis and classification of the disease, which is established after examination of a biopsy by a pathologist (usually a hematopathologist).
|Lymphoma type||Relative incidence||Histopathology||Immunophenotype||Overall|
|Precursor T-cell leukemia/lymphoma||40% of lymphomas in childhood.||Lymphoblasts with irregular nuclear contours, condensed chromatin, small nucleoli and scant cytoplasm without granules||TdT, CD2, CD7||It often presents as a mediastinal mass because of involvement of the thymus. It is highly associated with NOTCH1 mutations, and is most common in adolescent males.|
|Follicular lymphoma||About 40% of lymphomas in adults||Small "cleaved" cells (centrocytes) mixed with large activated cells (centroblasts), usually nodular ("follicular") growth pattern||CD10, surface Ig||72–77%||Occurs in older adults, usually involves lymph nodes, bone marrow and spleen, associated with t(14;18) translocation overexpressing Bcl-2, indolent|
|Diffuse large B cell lymphoma||About 40 to 50% of lymphomas in adults||Variable, most resemble B cells of large germinal centers, diffuse growth pattern||Variable expression of CD10 and surface Ig||60%||Occurs in all ages, but most commonly in older adults, often occurs outside lymph nodes, aggressive|
|Mantle cell lymphoma||3 to 4% of lymphomas in adults||Lymphocytes of small to intermediate size growing in diffuse pattern||CD5||50% to 70%||Occurs mainly in adult males, usually involves lymph nodes, bone marrow, spleen and GI tract, associated with t(11;14) translocation overexpressing cyclin D1, moderately aggressive|
|B-cell chronic lymphocytic leukemia/lymphoma||3 to 4% of lymphomas in adults||Small resting lymphocytes mixed with variable numbers of large activated cells, lymph nodes diffusely effaced||CD5, surface immunoglobulin||50%.||Occurs in older adults, usually involves lymph nodes, bone marrow and spleen, most patients have peripheral blood involvement, indolent|
|MALT lymphoma||About 5% of lymphomas in adults||Variable cell size and differentiation, 40% show plasma cell differentiation, homing of B cells to epithelium creates lymphoepithelial lesions.||CD5, CD10, surface Ig||Frequently occurs outside lymph nodes, very indolent, may be cured by local excision|
|Burkitt lymphoma||< 1% of lymphomas in the United States||Round lymphoid cells of intermediate size with several nucleoli, starry-sky appearance by diffuse spread with interspersed apoptosis||CD10, surface Ig||50%||Endemic in Africa, sporadic elsewhere, more common in immunocompromised and children, often visceral involvement, highly aggressive|
|Mycosis fungoides||Most common cutaneous lymphoid malignancy||Usually small lymphoid cells with convoluted nuclei that often infiltrate the epidermis, creating Pautrier microabscesseses||CD4||75%||Localized or more generalized skin symptoms, generally indolent, in a more aggressive variant, Sézary's disease, skin erythema and peripheral blood involvement|
|Peripheral T-cell lymphoma not otherwise specified||Most common T cell lymphoma||Variable, usually a mix small to large lymphoid cells with irregular nuclear contours||CD3||Probably consists of several rare tumor types, often disseminated and generally aggressive|
|Nodular sclerosis form of Hodgkin lymphoma||Most common type of Hodgkin lymphoma||Reed-Sternberg cell variants and inflammation, usually broad sclerotic bands that consist of collagen||CD15, CD30||Most common in young adults, often arises in the mediastinum or cervical lymph nodes|
|Mixed-cellularity subtype of [Hodgkin lymphoma||Second-most common form of Hodgkin lymphoma||Many classic Reed-Sternberg cells and inflammation||CD15, CD30||Most common in men, more likely to be diagnosed at advanced stages than the nodular sclerosis form Epstein-Barr virus involved in 70% of cases|
After a diagnosis and before treatment, a cancer is staged. This refers to deducing how far the cancer has spread, in local tissue and to other sites. Staging is reported as a grade between I (confined) and IV (spread). Staging is carried out because the stage of a cancer impacts its prognosis and treatment.
The Ann Arbor staging system is routinely used for staging of both HL and NHL. In this staging system, I represents a localized disease contained within a lymph node, II represents the presence of lymphoma in two or more lymph nodes, III represents spread of the lymphoma to both sides of the diaphragm, and IV indicates tissue outside a lymph node.
Age and poor performance status are established poor prognostic factors, as well.
Prognoses and treatments are different for HL and between all the different forms of NHL, and also depend on the grade of tumour, referring to how quickly a cancer replicates. Paradoxically, high-grade lymphomas are more readily treated and have better prognoses . A well-known example of a high-grade tumour is that of Burkitt lymphoma, which is a high-grade tumour known to double within days, but is readily treated. Lymphomas may be curable if detected in early stages with modern treatment.
Many low-grade lymphomas remain indolent for many years. Treatment of the nonsymptomatic patient is often avoided. In these forms of lymphoma, such as follicular lymphoma, watchful waiting is often the initial course of action. This is carried out because the harms and risks of treatment outweigh the benefits. If a low-grade lymphoma is becoming symptomatic, radiotherapy or chemotherapy are the treatments of choice; although they do not cure the lymphoma, they can alleviate the symptoms, particularly painful lymphadenopathy. Patients with these types of lymphoma can live near-normal lifespans, but the disease is incurable. Some centers advocate the use of single agent rituximab in the treatment of follicular lymphoma rather than the wait and watch approach. Watchful waiting is not a good strategy for all patients, as it leads to significant distress and anxiety in some patients. It has been equated with watch and worry.
Treatment of some other, more aggressive, forms of lymphoma[which?] can result in a cure in the majority of cases, but the prognosis for patients with a poor response to therapy is worse. Treatment for these types of lymphoma typically consists of aggressive chemotherapy, including the CHOP or R-CHOP regimen. A number of people are cured with first-line chemotherapy. Most patients relapse within the first two years, and the relapse risk drops significantly thereafter. For people who relapse, high-dose chemotherapy followed by autologous stem cell transplantation is a proven approach.
Hodgkin lymphoma typically is treated with radiotherapy alone, as long as it is localized.
Advanced Hodgkin disease requires systemic chemotherapy, sometimes combined with radiotherapy. Chemotherapy used includes the ABVD regimen, which is commonly used in the Unted States. Other regimens used in the management of Hodgkin lymphoma include BEACOPP and Stanford V. Considerable controversy exists regarding the use of ABVD or BEACOPP. Briefly, both regimens are effective, but BEACOPP is associated with more toxicity. Encouragingly, a significant number of people who relapse after ABVD can still be salvaged by stem cell transplant.
Palliative care, a specialized medical care focused on the symptoms, pain, and stress of a serious illness, is recommended by multiple national cancer treatment guidelines as an accompaniment to curative treatments for people suffering from lymphoma. It is used to address both the direct symptoms of lymphoma and many unwanted side effects that arise from treatments. Palliative care can be especially helpful for children who develop lymphoma, helping both children and their families deal with the physical and emotional symptoms of the disease. For these reasons, palliative care is especially important for patients requiring bone marrow transplants.
|Five-year relative survival by stage at diagnosis|
|Stage at diagnosis||Five-year relative|
of cases (%)
|Localized (confined to primary site)||82.1||27|
|Regional (spread to regional lymph nodes)||77.5||19|
|Distant (cancer has metastasized)||59.9||45|
Lymphoma is the most common form of hematological malignancy, or "blood cancer", in the developed world.
Taken together, lymphomas represent 5.3% of all cancers (excluding simple basal cell and squamous cell skin cancers) in the United States and 55.6% of all blood cancers.
According to the U.S. National Institutes of Health, lymphomas account for about 5%, and Hodgkin lymphoma in particular accounts for less than 1% of all cases of cancer in the United States.
Because the whole system is part of the body's immune system, patients with a weakened immune system such as from HIV infection or from certain drugs or medication also have a higher incidence of lymphoma.
Thomas Hodgkin published the first description of lymphoma in 1832, specifically of the form named after him. Since then, many other forms of lymphoma have been described, grouped under several proposed classifications. The 1982 Working formulation became very popular. It introduced the category non-Hodgkin lymphoma, divided into 16 diseases. However, because these lymphomas have little in common with each other, the NHL label is of limited usefulness for doctors or patients and is slowly being abandoned. The latest classification by the WHO (2008) lists 70 forms of lymphoma divided into four broad groups.
As an alternative to the American Lakes-Butler classification, in the early 1970s, Karl Lennert of Kiel, Germany, proposed a new system of classifying lymphomas based on cellular morphology and their relationship to cells of the normal peripheral lymphoid system.
Significant research into the causes, prevalence, diagnosis, treatment, and prognosis of lymphoma is being performed. Hundreds of clinical trials are being planned or conducted at any given time. Studies may focus on effective means of treatment, better ways of treating the disease, improving the quality of life for patients, or appropriate care in remission or after cures.
In general, the two types of lymphoma research are clinical or translational research and basic research. Clinical/translational research focuses on studying the disease in a defined and generally immediately patient-applicable way, such as testing a new drug in patients. By contrast, basic science research studies the disease process at a distance, such as seeing whether a suspected carcinogen can cause healthy cells to turn into lymphoma cells in the laboratory or how the DNA changes inside lymphoma cells as the disease progresses. The results from basic research studies are generally less immediately useful to patients with the disease, but can improve scientists' understanding of lymphoma and form the foundation for future, more effective treatments.
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Table 1.4: Age-Adjusted SEER Incidence and U.S. Death Rates and 5-Year Relative Survival Rates By Primary Cancer Site, Sex and Time Period
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