Long-term results of PET-guided radiation in patients with advanced-stage diffuse large B-cell lymphoma treated with R-CHOP

Abstract

Consolidative radiation therapy (RT) for advanced-stage diffuse large B-cell lymphoma (DLBCL) remains controversial with routine practice continuing to include RT in patients with initial bulky disease or residual masses. PET-CT is a sensitive modality for detecting the presence of residual disease at end-of-treatment (EOT). A PET-guided approach to selectively administer RT has been policy in BC since 2005. Patients with advanced-stage DLBCL diagnosed between January 2005 - March 2017 treated with at least 6 cycles of R-CHOP that underwent EOT-PET were included in this analysis. Those with complete metabolic response (PET-NEG) were observed; those with PET-positive scans (PET-POS) were offered consolidative RT, when feasible. 723 patients were identified with median follow-up of 4.3 years: 517 (72%) were PET-NEG; 206 (28%) were PET-POS. Time-to-progression (TTP) and overall survival (OS) at 3 years were 83% v 56% and 87% v 64%, for PET-NEG and PET-POS patients, respectively. Non-progressing PET-POS patients treated with consolidative RT (109/206, 53%) had outcomes approaching those of PET-NEG patients, with 3-year estimates of 76% and 80% for TTP and OS. PET-NEG patients with bulky disease (≥10 cm) at diagnosis, had outcomes indistinguishable from those without bulk, despite omitting RT. These data suggest that patients with advanced-stage DLBCL that are PET-NEG at EOT and receive no RT have excellent outcomes. FDG-PET can reliably guide selective administration of consolidative RT, even for patients with initially bulky disease.

Role of radiation therapy in primary tonsil large B cell lymphoma: a SEER-based analysis

“…The decreasing utilization of RT in PT-DLBCL over the past 2 decades might be associated with the individualized treatment strategies based on PET-CT and concern of RT related toxicities. The routine practice is to administer consolidative RT to those with positive end-of-treatment PET-CT based on available evidence [ 36 , 37 ]. As a result, post-chemotherapy PET-CT can better define subgroups that could benefit from RT and avoid over-treatment with RT utilization [ 38 ].…”

Moving the goalposts while scoring―the dilemma posed by new PET technologies

“…In advanced stage HL, the prospective, randomized controlled HD15 trial demonstrated that radiotherapy can be restricted to 11% of patients after effective first-line chemotherapy based on the presence or absence of FDG-avid residual disease (level 5 evidence) [18]. Subsequent randomized controlled trials showed that a favorable PET result also allows a reduction of chemotherapy in advanced-stage HL [15,19], may allow further de-escalation in selected patients in early stages of HL [20,21], and can reliably guide selective administration of consolidative radiotherapy in advancedstage diffuse large B-cell lymphoma (each level 5 evidence) [22].…”

Involved Site Radiation Therapy in Adult Lymphomas: An Overview of International Lymphoma Radiation Oncology Group Guidelines

“…84,85,111,113,[126][127][128][129][130][131][132] RT alone may salvage a proportion of patients with a residual PET-positive site. 133…”