Résumé
The benefit of radiotherapy (RT) following chemotherapy in limited-stage DLBCL remains controversial. Before the Rituximab era, 4 randomized trials have been reported with conflicting results (ECOG 1484 and SWOG 8736, GELA 93-1 and 93-4 studies). More recently, the German Unfolder study prematurely closed the R-CHOP without RT arm in bulky limited-stage DLBCL due to an excess of relapse. In 2005, we conducted a randomized trial in patients with non-bulky (defined by a tumor size <7cm) limited-stage DLBCL to evaluate the benefit of RT following R-CHOP.
Patients were stratified according to the Miller modified IPI including LDH (normal vs elevated), ECOG performance status (0-1 vs 2-3), age (<60 vs >60 yrs), stage (I vs II). Patients with IPI=0 (no risk factor) and those with IPI≥1 (≥1risk factor) received 4 or 6 consecutive cycles of R-CHOP 14 respectively, followed or not by IFRT at 40 GY delivered 4 weeks after the last cycle of R-CHOP. All patients were evaluated by an FDG-PET at baseline, after 4 cycles of R-CHOP and at the end of treatment. For patients in partial response (defined by a tumor regression >50% but a persistent positive FDG-PET) after C4, 2 additional cycles of R-CHOP followed by RT (even if not initially allocated) were recommended. The primary objective was EFS at one year after the last randomization, and secondary objectives were the impact of interim FDG-PET on EFS and the toxicity of RT.
From May 2005 to December 2013, 313 patients were randomized and 301 patients are currently evaluable. Median age was 56 yr (20-75). There were 181 males and 120 females: 106 patients (35%) were older than 60 yr. Most patients had normal LDH (82%), PS=0 (80%), and no B symptoms (96% of cases). Modified IPI score was as follows: IPI =0 (n=170), IPI=1 (n=113), IPI=2 (n=16), IPI=3 (n=2). Main tumor sites were cervical (n=159), Waldeyer’s ring and sinus (n=36), inguinal (n=29), axillary (n=25), mediastinum (n=21). Extra-nodal sites were observed in 121 patients (40%). One hundred and fifty patients were randomized in the R-CHOP arm and 151 in the R-CHOP + RT arm. After 4 cycles, 253 patients (84%) were in CR and 43 in PR (14%). Three patients had stable disease. Thirty-four patients (79%) out of the 43 partial responders received 2 additional cycles of R-CHOP followed by RT (including 12 patients not initially allocated to RT arm). At the end of treatment, CR and PR rate were 94% and 3%, respectively. Seven (4%) out of the 151 patients randomized in the RT arm declined radiation. With a median follow-up of 51 months (2-110), there were 20 relapses: 12 in the R-CHOP arm and 8 in the R-CHOP+RT arm (p=ns). Sixteen patients died. Causes of death were as follows: relapses (n=9), toxic (n=1), secondary malignancies (n=3), unknown (n=3). Median time of relapse was 21 months (2-110 months). EFS and OS are not statistically different between the two arms. In an intent to treat analysis, 5y-EFS is 87% n the R-CHOP arm versus 91% in the R-CHOP + RT arm (HR=0.55), p=0.13, and 5yr-OS is 90% in the R-CHOP arm versus 95% in the R-CHOP + RT arm (HR=0.60), p=0.32. For patients in complete response after the 4 cycles of R-CHOP (84% of the patients), 5yr-EFS is 89% in the R-CHOP arm versus 91% in the R-CHOP + RT arm (HR=0.59), p=0.24.
In this prospective study, the results demonstrate that in non-bulky limited-stage DLBCL, R-CHOP alone (4 to 6 cycles) induces very high CR rate with a very good overall survival and a very low relapse rate. With the current follow-up, the addition of radiotherapy is not significantly superior to R-CHOP alone and should be reserved to the minority of patients who do not reach CR after R-CHOP.