Non-Hodgkin’s Lymphoma |
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There are many similarities between non-Hodgkin’s lymphoma (NHL) and HL. The staging system is identical (Ann Arbor), as is the recommended volume for radiation therapy. For the most part radiation dosing is similar, but there are some differences. First, NHL is typically seen in older patients, with an average range of 60-65 years. Its incidence is rising, with known risk factors being immunodeficiency, environmental chemicals, certain viruses (EBV, HTLV-1, HHV-8), certain bacteria (H. Pylori), and radiation exposure. Histologically we no longer see Reed-Sternberg cells. NHL is broken down by the WHO classification into B-cell (80%) and T-cell (13%). B-cell lymphomas are primarily diffuse large B-cell (31%) and follicular (22%). T-cell lymphomas are usually NK/T cell and peripheral. Both cell lines are grouped by aggressiveness, with the low grade tumors being follicular, intermediate grade being DLBCL, NK/T, and mantle cell, and high grade being lymphoblastic and Burkitt’s lymphoma. In general, the low grade tumors tend to present at more advanced stages while the intermediate grades are more likely to present when they are early stage. Workup is similar, but will always include a bone marrow biopsy along with comprehensive bloodwork. A spinal tap and ophthamologic exam will be indicated for CNS lymphoma. Unlike HL, NHL has what is called an International Prognostic Index, which basically gives practitioners and patients an idea as to the overall prognosis of a tumor based on various risk factors. Adverse factors include age >60, stage III or IV, elevated LDH, poor performance status, or greater than one site with extranodal involvement. Overall survival based on these factors are as follows:
Treatment depends on stage and grade. Early stage low grade NHL can be treated with radiation therapy alone, while advanced cases are usually observed as long as they are asymptomatic. Otherwise they can be treated with chemotherapy or palliative radiation. Relapsed disease is often managed with high-dose chemotherapy with stem cell rescue, or with radioimmunotherapy with radiolabeled rituximab. Occasionally low grade NHL can transform into intermediate disease, at which point it is treated using the algorithm in the next paragraph. Localized intermediate grade NHL is managed with chemotherapy (CHOP + rituximab) for 3-4 cycles (favorable) to 6-8 cycles (unfavorable) and followed by involved field radiation therapy. Advanced stages are managed with chemotherapy for 6-8 cycles followed by radiation therapy to bulky sites. The role of up-front high dose chemotherapy with stem cell transplantation is controversial, but the role of this modality in the setting of relapse is clear. |