Primary lymphoma of the thyroid: clinical features, prognostic factors, and results of treatment.

This study analyzes the results of 46 cases of biopsy-proven primary lymphoma of the thyroid, localized at diagnosis and treated at the Royal Marsden Hospital between 1948-1980. In all cases, disease was limited to the thyroid and cervical lymph nodes. There were 43 females and 3 males, with a mean age of 64.4 years (median 66 years; range 17-86). A short history (less than 3 months) of a neck mass and local compressive symptoms was the typical presentation. The majority of patients (91%) had adverse histologies, with diffuse histiocytic lymphomas being most common (78%). The overall crude 5-year survival rate was 40%, with 30% of patients surviving beyond 10 years. Disease-free and overall survival were virtually identical, indicating the ineffectiveness of salvage therapy. The important prognostic factors were: size of tumor, fixation, extra-capsular extension, and retrosternal involvement. Survival was not correlated with age, sex, histology, thyroid status, or stage of disease, as defined by the Ann Arbor classification. Patients who had total macroscopic removal of tumor had the highest rate of local control and long survival (p less than 0.005). No significant difference was seen between lobectomy, subtotal or total thyroidectomy, but 7 of 9 long-term survivors (58-129 months) have had total thyroidectomy. A radiotherapy dose to the tumor, of at least 40 Gy, was required to produce consistent local control in patients with unresected disease. The majority of patients who died had generalized disease. Only 52% of these patients were free of local recurrence. In view of the frequency of occult disseminated disease, adjuvant chemotherapy is one recommendation for patients with poor prognostic factors. For optimal local control, complete surgical eradication is recommended followed by high-dose local radiotherapy. The use of aggressive cytoreductive chemotherapy prior to radiotherapy is a possible alternative option which needs to be explored.