NON-HODGKIN’S LYMPHOMAS (NHLs)
The NHLs are a heterogeneous group of cancers that originate from the neoplastic growth of lymphoid tissue. As in CLL, the neo-plastic cells are thought to arise from a single clone of lymphocytes; however, in NHL, the cells may vary morphologically. Most NHLs involve malignant B lymphocytes; only 5% involve T lymphocytes. In contrast to Hodgkin’s disease, the lymphoid tissues involved are largely infiltrated with malignant cells.
The spread of these malignant lymphoid cells occurs unpredictably, and true localized disease is uncommon. Lymph nodes from multiple sites may be infiltrated, as may sites outside the lymphoid system (extranodal tissue).
The incidence of NHL has increased dramatically over the past decade; it is now the fourth most common type of cancer diag-nosed in the United States and the fifth most common cause of cancer death (Greenlee, Hill-Horton, Murray, & Thun, 2001; Zelenetz et al., 2000). The incidence increases with each decade of life; the average age at diagnosis is 50 to 60 years. Although no com-mon etiologic factor has been identified, there is an increased inci-dence of NHL in people with immunodeficiencies or autoimmune disorders, viral infections (including Epstein-Barr virus and HIV), or exposure to pesticides, solvents, or dyes. Prognosis varies greatly among the various types of NHL. Long-term survival (more than 10 years) is commonly achieved in low-grade, localized lym-phomas. Even with aggressive disease forms, cure is possible in at least one third of patients who receive aggressive treatment.
Symptoms are highly variable, reflecting the diverse nature of these diseases. With early-stage disease, or with the types that are con-sidered more indolent, symptoms may be virtually absent or very minor, and the illness typically is not diagnosed until it progresses to a later stage, when the patient is more symptomatic. At these stages (III or IV), lymphadenopathy is noticeable. One third of pa-tients have “B symptoms” (recurrent fever, drenching night sweats, and unintentional weight loss of 10% or more).
The actual diagnosis of NHL is categorized into a highly complex classification system based on histopathology, immunophenotyp-ing, and cytogenetic analyses of the malignant cells. The specific histopathologic type of the disease has important prognostic im-plications. Treatment also varies and is based on these features. In-dolent (less aggressive) types tend to have small cells and are distributed in a follicular pattern. Aggressive types tend to have large or immature cells distributed through the nodes in a diffuse pattern. Staging, also an important factor, is typically based on data obtained from CT scans, bone marrow biopsies, and occasionally cerebrospinal fluid analysis. The stage is based on the site of dis-ease and its spread to other sites. For example, in stage I disease, only one area of involvement is detected; thus, stage I disease is highly localized and may respond well to localized therapy (eg, ra-diation therapy). In contrast, stage IV disease is detected in at least one extranodal site. Although low-grade lymphomas may not re-quire treatment until the disease progresses to a later stage, histor-ically they have also been relatively unresponsive to treatment in that most therapeutic modalities did not improve overall survival. More aggressive types of NHL (eg, lymphoblastic lymphoma, Burkitt’s lymphoma) require prompt initiation of chemotherapy; however, these types tend to be more responsive to treatment.
Treatment is based on the actual classification of disease, the stage of disease, prior treatment (if any), and the patient’s ability to tol-erate therapy. If the disease is not an aggressive form and is truly localized, radiation alone may be the treatment of choice. With aggressive types of NHL, aggressive combinations of chemother-apeutic agents are given even in early stages. More intermediate forms are commonly treated with combination chemotherapy and radiation therapy for stage I and II disease. The biologic agent interferon has been approved for the treatment of follicular low-grade lymphomas, and an antibody to CD20, rituximab (Rit-uxan), has been effective in achieving partial responses in patients with recurrent low-grade lymphoma. Studies of this agent in com-bination with conventional chemotherapy have demonstrated an improvement in survival as well (Coiffier, 2002; Emmanouilides et al., 2000; Petryk & Grossbard, 2000). Central nervous system involvement is also common with some aggressive forms of NHL; in this situation, cranial radiation or intrathecal chemotherapy is used in addition to systemic chemotherapy. Treatment after re-lapse is controversial. BMT or PBSCT may be considered for pa-tients younger than 60 years of age.
Most of the care for patients with Hodgkin’s disease or NHL is performed in the outpatient setting, unless complications occur (eg, infection, respiratory compromise due to mediastinal mass). For patients who require treatment, chemotherapy and radiation therapy are most commonly used. Chemotherapy causes systemic side effects (eg, myelosuppression, nausea, hair loss, risk for infec-tion), whereas the side effects from radiation therapy are specific to the area being irradiated. For example, patients receiving ab-dominal radiation therapy may experience nausea and diarrhea but not hair loss. Regardless of the type of treatment, all patients may experience fatigue.
The risk of infection is significant for these patients, not only from treatment-related myelosuppression but also from the defec-tive immune response that results from the disease itself. Patients need to be taught to minimize the risks for infection, to recognize signs of possible infection, and to contact the health care profes-sional should such signs develop (see Chart 33-8).
Many lymphomas can be cured with current treatments. However, as survival rates increase, the incidence of second ma-lignancies, particularly AML or MDS, also increases. Therefore, survivors should be screened regularly for the development of sec-ond malignancies.
Lymphoma is a highly complex constellation of diseases. When caring for the patient with lymphoma, it is extremely important to know the specific disease type, stage of disease, treatment his-tory, and current treatment plan.
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