Central lymphatic irradiation for stage I–III follicular lymphoma: report from a single-institutional prospective study

Abstract

Purpose This study was undertaken to update our experience with follicular lymphoma treated with central lymphatic irradiation (CLI). Methods and materials A total of 47 patients were treated with CLI between January 1993 and March 2000 in a prospective manner. CLI consisted of mantle, whole abdomen, and pelvic radiation fields with a 1-month break after each field. Each field was treated to 3000–3060 cGy at 150–180 cGy per fraction followed by a boost dose of 900 cGy to the areas with gross disease. The median age was 52 years (range: 29–73 years). There were 29 males. The diagnoses were as follows: follicular small cleaved-cell lymphoma, 23 patients; follicular mixed-cell lymphoma, 19 patients; follicular large-cell lymphoma, 5 patients. Ann Arbor stages were as follows: I, 5 patients; II, 14 patients; and III, 28 patients. The International Prognostic Index (IPI) categories were as follows: 0, 14 patients; 1, 24 patients; and 2, 9 patients. M. D. Anderson Tumor Score was as follows: 0, 14 patients; 1, 18 patients; 2, 9 patients; 3, 4 patients; 4, 1 patient; and unknown, 1 patient. Two patients had abnormal LDH levels, and 11 patients had β2M levels >2 mg/dL. Gender, pathology, stage, IPI, Anderson Tumor Score, β2M, and number of disease sites were examined for significance in freedom from progression (FFP) by univariate analyses. Results The median follow-up was 54 months (range: 8–93 months) for the 45 surviving patients. Every patient achieved a complete response, except for 1 patient whose lymphoma progressed to diffuse large-cell lymphoma during treatment. The 5-year overall survival and FFP were 94% and 53%, respectively. No failure has yet been observed beyond 55 months of follow-up with 13 patients at risk. Patterns of failure were as follows: within the radiation field, 10; outside the fields, 4; and both, 2. Of the seven variables investigated, β2M >2 mg/dL and IPI >1 were the only significant adverse prognostic factors for FFP ( p = 0.023 and 0.046, respectively). Conclusions CLI is well tolerated and seems to achieve durable FFP in about half of the patients with Stage I–III follicular lymphoma. Most of the experiences with CLI come from the treatment of Stage III disease and are very similar to our previous experience with combined modality treatment. Whether a plateau in FFP can be maintained beyond 5 years remains to be seen.