SAN DIEGO –
For example, radiation may not be needed for advanced-stage patients who’ve received at least four cycles of R-CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisolone plus rituximab), and whose PET scans show no sign of disease at interim or end-of treatment phases, said Joanna Yang, MD, MPH, of Washington University in St. Louis, in a presentation at the annual meeting of the American Society for Radiation Oncology.
These patients “may be able to omit radiotherapy without sacrificing good outcomes,” Dr. Yang said. In contrast, those whose PET scans show signs of disease at interim and end-of-treatment points may benefit from radiotherapy to selected sites, she said.
Dr. Yang highlighted a 2021 study in Blood that tracked 723 patients with advanced-stage DLBCL who were diagnosed from 2005 to 2017. All were treated with R-CHOP, and some of those who were PET-positive – that is, showing signs of malignant disease – were treated with radiotherapy.
Over a mean follow-up of 4.3 years, the study reported “time to progression and overall survival at 3 years were 83% vs. 56% and 87% vs. 64% in patients with PET-NEG and PET-POS scans, respectively.”
These findings aren’t surprising, Dr. Yang said. But “the PET-positive patients who got radiation actually had outcomes that came close to the outcomes that the PET-negative patients were able to achieve.” Their 3-year overall survival was 80% vs. 87% in the PET-negative, no-radiation group vs. 44% in the PET-positive, no-radiation group.
Dr. Yang cautioned, however, that withholding radiation in PET-negative patients isn’t right for everyone: “This doesn’t mean this should be the approach for every single patient.”
What about early-stage DLBCL? In patients without risk factors, Dr. Yang recommends PET scans after four treatments with R-CHOP. “Getting that end-of-treatment PET is going to be super-critical because that’s going to help guide you in terms of the patients who you may feel comfortable omitting radiation versus the patients who remain PET-positive at the end of chemotherapy. Many places will also add an interim PET as well.”
According to her, radiotherapy is appropriate in patients who are PET-positive, based on the findings of the FLYER and LYSA-GOELAMS 02-03 trials.
In early-stage patients who have risk factors such as advanced age or bulky or extra-nodal disease, Dr. Yang suggests examining interim PET scans after three treatments with R-CHOP. If they are negative, another R-CHOP treatment is appropriate – with or without radiotherapy.
“There’s a lot that goes into that decision. The first thing I think about in patients who have risk factors is: What salvage options are available for my patient? Can they tolerate these salvage option? If they’re older, they might not be eligible for auto [autologous hematopoietic cell transplantation]. If they’re frail, they might not be eligible for auto or CAR T cells. If they have bulk, it’s certainly an area of concern. It seems like radiation does help control disease in areas of bulk for patients with DLBCL.”
If these patients are PET-positive, go directly to radiotherapy, Dr. Yang advised. Trials that support this approach include S1001, LYSA-GOELAMS 02-03, and RICOVER-noRTH, she said.
What about double-hit and triple-hit lymphomas, which are especially aggressive due to genetic variations? Research suggests that “even if double hit/triple hit is not responding to chemo, it still responds to radiation,” Dr. Yang said.
In regard to advanced-stage disease, “if patients are receiving full-dose chemo for least six cycles, I use that end-of-treatment PET to help guide me. And then I make an individualized decision based on how bulky that disease is, where the location is, how morbid a relapse would be. If they’re older or receiving reduced-dose chemotherapy, then I’ll more seriously consider radiation just because there are limited options for these patients. And we know that DLCBL is most commonly a disease of the elderly.”
In an adjoining presentation at ASTRO, Andrea Ng, MD, MPH, of Harvard Medical School/Dana-Farber Brigham Cancer Center, Boston, discussed which patients with incomplete response or refractory/relapsed DLCBL can benefit from radiotherapy.
She highlighted patients with good partial response and end-of-treatment PET-positive with evidence of residual 18F-fluorodeoxyglucose activity via PET scan (Deauville 4/5) – a group that “we’re increasingly seeing.” In these patients, “radiation can be quite effective” at doses of 36-45 Gy. She highlighted a study from 2011 that linked consolidation radiotherapy to 5-year event-free survival in 65% of patients.
As for relapsed/refractory disease in patients who aren’t candidates for further systemic therapy – the “frail without good options” – Dr. Ng said data about salvage radiotherapy is limited. However, a 2015 study tracked 65 patients who were treated with a median dose of 40 Gy with “curative” intent. Local control was “not great” at 72% at 2 years, Dr. Ng said, while overall survival was 60% and progress-free survival was 46%.
Dr. Ng, who was one of this study’s authors, said several groups did better: Those with refractory vs. relapsed disease and those who were responsive to chemotherapy vs. those who were not.
She also highlighted a similar 2019 study of 32 patients with refractory/relapsed disease treated with salvage radiotherapy (median dose of 42.7 Gy) found that 61.8% reached progress-free survival at 5 years – a better outcome.
Dr. Yang has no disclosures. Dr. Ng discloses royalties from UpToDate and Elsevier.