Lymphomas

Once diagnosed, patients should be staged by chest X-ray, chest and abdominal CAT scans, bone marrow biopsy, and gallium scan. In 20-30% of patients, the lymphoma will be confined within the thyroid gland. Lymph nodes are involved in approximately 60% of the patients, and perithyroidal invasion is present in about half. When patients have undergone appropriate staging procedures, 20-30% will have Stage IIIE (lymphoma present in nodes below the diaphragm) or Stage IVE (distant extranodal metastases) disease. The selection of appropriate therapy requires prior staging of the patient. As these tumors are radiosensitive, external radiation therapy is a satisfactory treatment for Stage I-E (local disease only, no nodal involvement) and has been used for Stage II-E (nodal involvement above the diaphragm only) disease. The dose to the neck is usually 4,000 rads (40 Gy) over 4-5 weeks (530). The radiation port should include the mediastinum even in the absence of clinical involvement. When evaluating the long-term survival of patients with Stage I and Stage II disease, Souhami et al. found that of seven patients treated with radiation to the neck only, five died within 5 years, whereas in five patients receiving radiation to the neck and mediastinum, there were no deaths (531). Patients with unfavorable prognostic factors such as age > 60 yr, large mass or tumor necrosis, may be given chemotherapy after radiotherapy. In radiation-treated patients with local extension or with malignant nodes, the survival after surgery is unaffected by the extent of surgery even when surgery was limited to a biopsy. With obvious extension or nodal involvement, surgery should be limited to obtaining an adequate diagnostic specimen since an attempt at complete excision may damage surrounding structures without improving survival. There is a suggestion that total thyroidectomy may improve the prognosis in patients with intrathyroidal disease only (532).

There is a growing tendency to use combination chemotherapy as the initial definitive treatment for Stage IE and IIE thyroid lymphoma, rather than radiation. Programs may combine cyclophosphamide, adriamycin, vincristine, and prednisolone ("CHOP"). This approach may increase cure above the 30-50% found with radiotherapy alone (533). Currently most patients with Stage II-E, and patients with Stage III-E or Stage IV-E disease, as well as those who relapse after radiation therapy, are treated with chemotherapy, given every 3-4 weeks for 3-6 cycles, prior to radiation therapy if combined with that treatment. Although previous series report overall 5-year survivals of about 50%, certain subgroups have a more favorable prognosis. With appropriate staging to exclude Stage III-E and Stage IV-E patients, the Stanford group has reported a 3-year survival of 83% and at 3 years 75% of their Stage I-E and Stage II-E patients had no evidence of disease (534). Matsuzuka et al (535) used both radiation therapy and six courses of "CHOP" chemotherapy, and report 100% survival for 8 years in a group of patients who received this treatment.