Lymphoma-Non-Hodgkin

Note: Estimated new cases and deaths from non-Hodgkin's lymphoma (NHL) in the United States in 2005:

• New cases: 56,390.
• Deaths: 19,200.

The NHLs are a heterogeneous group of lymphoproliferative malignancies with differing patterns of behavior and responses to treatment.

Like Hodgkin’s lymphoma, NHL usually originates in lymphoid tissues and can spread to other organs. NHL, however, is much less predictable than Hodgkin’s lymphoma and has a far greater predilection to disseminate to extranodal sites. The prognosis depends on the histologic type, stage, and treatment.

The NHLs can be divided into 2 prognostic groups: the indolent lymphomas and the aggressive lymphomas. Indolent NHL types have a relatively good prognosis, with median survival as long as 10 years, but they usually are not curable in advanced clinical stages. Early stage (stage I and stage II) indolent NHL can be effectively treated with radiation therapy alone. Most of the indolent types are nodular (or follicular) in morphology. The aggressive type of NHL has a shorter natural history, but a significant number of these patients can be cured with intensive combination chemotherapy regimens. In general, with modern treatment of patients with NHL, overall survival at 5 years is approximately 50% to 60%. Of patients with aggressive NHL, 30% to 60% can be cured. The vast majority of relapses occur in the first 2 years after therapy. The risk of late relapse is higher in patients with a divergent histology of both indolent and aggressive disease.

While indolent NHL is responsive to radiation therapy and chemotherapy, a continuous rate of relapse is usually seen in advanced stages. Patients, however, can often be re-treated with considerable success as long as the disease histology remains low grade. Patients who present with or convert to aggressive forms of NHL may have sustained complete remissions with combination chemotherapy regimens or aggressive consolidation with marrow or stem cell support.

Radiation techniques differ somewhat from those used in the treatment of Hodgkin’s lymphoma. The dose of radiation therapy usually varies from 2,500 cGy to 5,000 cGy and is dependent on factors that include the histologic type of lymphoma, the patient’s stage and overall condition, the goal of treatment (curative or palliative), the proximity of sensitive surrounding organs, and whether the patient is being treated with radiation therapy alone or in combination with chemotherapy. Given the patterns of disease presentations and relapse, treatment may need to include unusual sites such as Waldeyer’s ring, epitrochlear, or mesenteric nodes. The associated morbidity of the treatment, however, must be considered carefully. The majority of patients who receive radiation are usually treated on only 1 side of the diaphragm. Localized presentations of extranodal NHL may be treated with involved-field techniques with significant (>50%) success.

In asymptomatic patients with indolent forms of advanced NHL, treatment may be deferred until the patient becomes symptomatic as the disease progresses. When treatment is deferred, the clinical course of patients with indolent NHL varies; frequent and careful observation is required so that effective treatment can be initiated when the clinical course of the disease accelerates. Some patients have a prolonged indolent course, but others have disease that rapidly evolves into more aggressive types of NHL that require immediate treatment.

Aggressive lymphomas are increasingly seen in HIV-positive patients; treatment of these patients requires special consideration.