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

• Published in: Blood 2021-02, Vol.137 (7), p.929-938
• Main Authors: Freeman, Ciara L., Savage, Kerry J., Villa, Diego R., Scott, David W., Srour, Line, Gerrie, Alina S., Brown, Maura J., Slack, Graham W., Farinha, Pedro, Skinnider, Brian, Morris, James, Bénard, François, Aquino-Parsons, Christina, Lo, Andrea, Pickles, Tom, Wilson, Don C., Tonseth, Petter, Connors, Joseph M., Sehn, Laurie H.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.2020005846

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. Positron emission tomography (PET)-computed tomography is a sensitive modality for detecting the presence of residual disease at the end of treatment (EOT). A PET-guided approach to selectively administering RT has been the policy in British Columbia since 2005. Patients with advanced-stage DLBCL diagnosed from 1 January 2005 to 1 March 2017 and treated with at least 6 cycles of R-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone plus rituximab), who underwent EOT PET, were included in this analysis. Those with complete metabolic response (PET-negative [PET-NEG]) were observed; those with PET-positive (PET-POS) scans were offered consolidative RT, when feasible. Of the patient records reviewed, 723 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% vs 56% and 87% vs 64%, in patients with PET-NEG and PET-POS scans, respectively. PET-POS patients with nonprogressing disease treated with consolidative RT (109 and 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 who had bulky disease (≥10 cm) at diagnosis had outcomes indistinguishable from those without bulk, despite the omission of RT. These data suggest that patients with advanced-stage DLBCL who are PET-NEG at EOT and receive no RT have excellent outcomes. 18F-fluorodeoxyglucose-PET can reliably guide selective administration of consolidative RT, even in patients with initially bulky disease. •Patients with advanced DLBCL who have a negative EOT PET scan have an excellent prognosis without RT.•PET-POS patients with nonprogressing disease given RT at EOT have better-than-expected outcomes, providing rationale for this approach. [Display omitted]