Limited-Stage Diffuse Large B-Cell Lymphoma (DLBCL) Patients with a Negative Pet Scan Following Three Cycles of R-CHOP Can Be Effectively Treated with Abbreviated Chemoimmunotherapy Alone.

Four cycles of CHOP chemotherapy has been shown to be sufficient treatment for low-risk elderly patients with limited-stage DLBCL, eliminating the need for radiation therapy (Bonnet et al, JCO 2007). FDG-PET scanning is an effective prognostic tool that may identify chemo-sensitive patients (regardless of age or clinical risk factors) who can appropriately be treated with abbreviated chemoimmunotherapy alone. Patients: Beginning in 2005, we have recommended that all prospective patients with limited-stage DLBCL (stage I/II, no B-symptoms, mass < 10cm) treated in British Columbia (BC) undergo a PET scan following 3 cycles of R-CHOP; PET-negative patients should then receive one additional cycle of R-CHOP (total 4 cycles R-CHOP), while PET-positive patients receive involved-field radiation therapy (IFRT). Clinical characteristics of the first 50 patients are as follows: median age 67 y (range 31–88); 56% male; 62% stage I, 38% stage II; 4% PS>1; 6% elevated LDH; 58% at least 1 extranodal site, 10% >1 extranodal site. Stage-modified IPI risk factors: 22% 0; 70% 1–2; 8% 3–4. Median follow-up is 17 mos (range 4–26).

Results: 37 patients (74%) were PET-negative and 13 patients (26%) were PET-positive after 3 cycles of R-CHOP. No clinical factors were found to be predictive of PET status. Of the 37 PET-negative patients, 35 completed treatment with one additional cycle of chemoimmunotherapy, 1 received IFRT due to poor chemotherapy tolerance, and 1 died of toxicity before receiving any more treatment. Only 1/37 PET-negative patients has relapsed (alive with lymphoma after salvage therapy). All 13 PET-positive patients received IFRT, with 3 relapses and 2 deaths from lymphoma to date. Although longer follow-up is necessary, the 2-year estimated Kaplan-Meier progression-free survival is 91% overall (97% and 75% for PET-negative and PET-positive patients, respectively, p=0.09). (see figure) The 2-year estimated Kaplan-Meier overall survival is 97% for PET-negative and 69% for PET-positive patients, p=0.1.

Conclusion: Patients with limited-stage DLBCL who are PET-negative after 3 cycles of R-CHOP can be effectively treated with abbreviated chemoimmunotherapy alone (4 cycles R-CHOP), avoiding the long-term toxicity of radiation while preserving excellent lymphoma control.

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