Radiotherapy dose-response analysis for diffuse large B-cell lymphoma with a complete response to chemotherapy.
OBJECTIVE
To examine the efficacy of different radiation doses after achievement of a complete response to chemotherapy in diffuse large B-cell lymphoma (DLBCL).


METHODS
Patients with stage I-IV DLBCL treated from 1995-2009 at Duke Cancer Institute who achieved a complete response to chemotherapy were reviewed. In-field control, event-free survival, and overall survival were calculated using the Kaplan-Meier method. Dose response was evaluated by grouping treated sites by delivered radiation dose.


RESULTS
105 patients were treated with RT to 214 disease sites. Chemotherapy (median 6 cycles) was R-CHOP (65%), CHOP (26%), R-CNOP (2%), or other (7%). Post-chemotherapy imaging was PET/CT (88%), gallium with CT (1%), or CT only (11%). The median RT dose was 30 Gy (range, 12-40 Gy). The median radiation dose was higher for patients with stage I-II disease compared with patients with stage III-IV disease (30 versus 24.5 Gy, p < 0.001). Five-year in-field control, event-free survival, and overall survival for all patients was 94% (95% CI: 89-99%), 84% (95% CI: 77-92%), and 91% (95% CI: 85-97%), respectively. Six patients developed an in-field recurrence at 10 sites, without a clear dose response. In-field failure was higher at sites ≥ 10 cm (14% versus 4%, p = 0.06).


CONCLUSIONS
In-field control was excellent with a combined modality approach when a complete response was achieved after chemotherapy without a clear radiation dose response.
Department of Radiation Oncology, University Hospitals Seidman Cancer Center and Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA. jdorth@gmail.com
Jennifer A
JA
Dorth
Leonard R
LR
Prosnitz
Gloria
G
Broadwater
Anne W
AW
Beaven
Chris R
CR
Kelsey
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage; D059248:Chemoradiotherapy; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D055815:Young Adult