SAN FRANCISCO—The addition of radiotherapy (RT) should be reserved for the minority of patients with non-bulky limited-stage diffuse large B cell lymphoma (DLBCL) who do not reach a complete response (CR) with R-CHOP alone (Abstract 393), investigators reported at the 56th American Society of Hematology (ASH) Annual Meeting and Exposition.
Preliminary results of the prospective randomized phase 3 study from the Lysa/Goelams Group found that 4 to 6 cycles of R-CHOP alone induced a very high CR rate “with a very good overall survival and a very low relapse rate,” said Thierry Lamy, MD, PhD, of the Hematology Department at INSERM U917/University Hospital of Rennes in Rennes, France.
“The benefit of radiotherapy following chemotherapy in limited-stage DLBCL remains controversial,” he said, in explaining why the study was initiated in May 2005. Non-bulky was defined as a tumor size of less than 7 cm.
Patients with no modified International Prognostic Index (IPI) risk factors received 4 consecutive cycles and those with at least 1 risk factor received 6 consecutive cycles of R-CHOP 14, with IFRT 40 Gy (151 patients) or without (50 patients). An additional 2 cycles of R-CHOP followed by RT were recommended for those who had a partial response (PR).
Of the 336 randomly assigned patients, 301 were evaluable for response. Of the 151 patients randomly assigned to radiotherapy, 7 (4%) declined treatment.
After 4 cycles, 124 patients (82%) in the R-CHOP arm and 129 (85%) in the R-CHOP plus RT arm had a complete response (CR); 16% and 12% of patients in each arm, respectively, had a PR. One patient in the R-CHOP arm and 2 in the R-CHOP plus RT had stable disease.
Of the 43 patients who had PRs at cycle 4, 37 (86%) received 2 additional cycles of R-CHOP and RT and 6 had another regimen with and without RT; 40 of those patients entered CR, Dr. Lamy said.
At a median follow-up of 51 months (range, 2-100 months), 20 patients had relapsed at a median time to relapse of 21 months (range 4-93), 12 in the R-CHOP arm and 8 in the R-CHOP plus RT arm, a difference that was not statistically significant (P=0.27).
The event-free survival (EFS) and overall survival (OS) rates were not significantly different between arms; 5-year EFS was 88.4% in the R-CHOP arm versus 87.3% in the R-CHOP plus RT arm (hazard ratio [HR] 0.55; 95% confidence interval [CI] 0.26-1.17; P=0.13) and 5-year OS was 92% in the R-CHOP arm versus 90% in the R-CHOP plus RT arm (HR 0.60; 95% CI 0.23-1.62; P=0.33).
Multivariate analysis of EFS and OS stratified by IPI scores 0, 1, 2, and 3 showed significantly lower rates with increasing risk score (P=0.0015 for EFS and P=0.001 for OS).
Sixteen patients died: 9 from progressive disease, 1 from toxicity, 1 from acute leukemia, 1 from a solid tumor, 1 from a car crash, and 3 patients died from unknown causes.