Findings from a small, retrospective study showed that external beam radiation therapy (EBRT) induced an overall response rate of 86% in patients with relapsed/refractory follicular lymphoma.
At median follow-up of 3 months, 13 of 15 patients achieved a response with EBRT. The complete response rate was 73% (n = 11) and the partial response rate was 13% (n = 2). After 1 or 2 courses of EBRT, two-thirds of patients reached disease control.
Summarizing their findings, the investigators noted, “This small pioneer study suggests that a multimodality approach including external beam radiotherapy may achieve high success rate with minimal toxicities in relapsed and refractory follicular lymphoma although a great scope for improvement exists for radiation procedures.”
Using the Curie institute database, the investigators identified 27 patients who were diagnosed with follicular lymphoma and treated with radiotherapy between June 1995 and February 2014. The final analysis excluded 12 patients for various reasons, including receiving first-line or consolidative radiotherapy (n = 4), having exclusive skin or bone localization (n = 6), having primary transformed follicular lymphoma (n = 1), and insufficient data (n = 1).
The median age of the 15 evaluable patients was 68.2 (range, 38-86). There were 11 women and 4 men. The median FLIPI score was 2 (range, 0-4), and 7 patients had stage I/II disease, with the remaining 8 having stage III/IV.
Two patients had bulky disease (>7 cm) and 4 patients’ tumors transformed into aggressive lymphoma at a median of 29.4 months (range, 0-34.5) after diagnosis. In all instances, the transformation took place after irradiation.
Eleventh patients (73%) had relapsed disease and 4 patients (27%) had refractory. Five patients had stage I disease at relapse, with the remaining 6 patients having stage 2.
Twelve patients received involved site radiotherapy, and the other 3 received Involved field radiotherapy. Five patients received intensity-modulated radiotherapy by Tomotherapy, and the other 10 received radiotherapy with a 6 to 20 MV linear accelerator with lower energies used for superficial disease.
Ten patients received systemic therapy at relapse, including 10 with chemotherapy; 8 with anti-CD20 antibodies, such as rituximab (Rituxan); and 5 with an anthracycline-based regimen. Three patients had second-line chemotherapy. No patient received autologous stem cell transplant following relapse.
The median dose of EBRT was 30 Gy (range, 2-40) and the median number of fractions was 15 (range, 2-20). Eighty-six percent of patients were in remission at last follow-up, including those who received salvage chemotherapy.
Eight patients (53%) relapsed at a median of 20.2 months after EBRT. Five of these patients relapsed in the irradiated localization, following 2 irradiations of 2 Gy. Contralateral nodal relapse occurred in the other 3 patients.
Three of the patients who relapsed had a new irradiation at a median of 23.3 months, with all 3 having a response, including 2 complete responses and 1 partial response. At a median of 8.1 months (range, 3.0-15.2), none had an additional relapse.
According to univariate analysis, the only predicting factor for non-control disease was Follicular Lymphoma International Prognostic Index (FLIPI) score >2 (odds ratio = 21; P
Regarding safety, the investigators wrote, “Toxicity induced by radiotherapy was very low. No events above grade 1 were noted, with 1 mucitis, 1 radio dermatitis, and 1 xerostomia.”
Grignano É, Deau-Fischer B, Loganadane G, et al. Radiotherapy of relapse-refractory follicular lymphoma [published on line Feb 21, 2018]. Cancer Radiother. doi: 10.1016/j.canrad.2017.09.003.