Rituximab Followed by Involved Fields Radiotherapy (IF-RT) in Stage I-II Follicular Lymphoma (FL): Long Term Results,

Radiotherapy is considered the standard approach in stage I-II non bulky FL but no consensus of the required radiation field has been reached and failure-free survival (FFS) reported ranged between 41 to 49%. Published randomized trials failed to demonstrate the superiority of non adriamycin-containing regimens plus RT over RT alone and only one single arm study with COP-B plus IF-RT reported superior FFS (73%) however complicated by an high rate of treatment related toxicity. Since the monoclonal anti CD-20 antibody Rituximab has shown to be effective in systemic therapy of FL as primary treatment as well at relapse, the combination of the anti-CD20 Rituximab with IF-RT may be considered a valid approach, allowing an effective systemic disease control while sparing the toxicity of chemotherapy. We reported here the long-term outcome of a series of stage I-II FL pts treated front-line with Rituximab followed by IF-RT. Patients and Methods: From July 1999 to April 2009, 36 consecutive stage I-II FL WHO grade I-II, have been enrolled in this phase II study and treated with 4 weekly doses of Rituximab followed by IF-RT. Median age: 49 yrs (range 34–82), M/F: 20/16; FLIPI 0–1: 36; Bulky:0. BM PCR analysis to detect minimal residual disease (MRD) was carried out in 25 pts with a molecular probe: PCR+/PCR-: 10/15. Treatment consisted of 4 weekly doses of Rituximab (375 mg/sqm) followed by external bean RT on involved fields. Median radiation dose was 30.6 Gy, (range 20–40). Results: Rituximab followed by IF-RT was well tolerated without any additional toxicity. All but one pts reached a complete remission (CR). With a median follow-up of 7 years (range: 2–12), 34 pts are alive and 24 in continuous complete remission. Of the 12 relapsed pts, 6 were PCR+ versus 4 PCR- at baseline BM analysis; 2 pts had no molecular probe. Two smokers pts died of lung cancer at 3 and 4 years after immuno-radiotherapy. The OS and FFS were 94% and 67% respectively. These results compare favorably with those observed in similar historical control group treated at our Institution with IF-RT alone (OS:87%,FFS:46.8%). Conclusion: Rituximab followed by IF-RT is a well tolerated and effective front-line treatment for limited stage FL. Long-term results are comparable to those reported for non-anthracycline-containing chemo-radiotherapy and higher when compared to radiotherapy alone, making Rituximab-IF-RT a potential option as initial therapy of limited stage FL.

No relevant conflicts of interest to declare.