Reviewing radiation therapy options for patients with relapsed or persistent DLBCL

This study reviewed several studies involving patients with relapsed or refractory (does not respond to treatment) diffuse large B-cell lymphoma (DLBCL) who received radiation therapy (RT). The authors concluded that RT can improve outcomes and disease control for patients with localized disease.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of aggressive non-Hodgkin's lymphoma (NHL). DLBCL represents about 30% of new NHL cases in the U.S. The most widely used treatment for this aggressive cancer is R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). About 10 – 15% of patients treated with R-CHOP develop refractory disease, while another 20 – 25% experience relapse.

Only about half of these patients are eligible for a stem cell transplant (SCT). Of these, only half have chemosensitive (responds to chemotherapy) disease, which is needed for successful SCT. For these patients, therapy options are limited. Consolidative or salvage radiotherapy (RT) is used to eliminate remaining cancer. Data about the impact of RT on the outcomes of these patients is limited, and remains under investigation.

For transplant-eligible patients, RT given around the time of transplant (peri-transplant) can improve disease control and outcomes. In a study of 65 patients, 11.8% (RT after SCT) versus 35.5% (no RT) experienced relapse after SCT. These patients had negative PET scans (no remaining cancer) before SCT. The authors recommended that patients with positive PET scans undergo RT before SCT to ensure a successful transplant. RT can be also be an effective salvage treatment pre-SCT for eligible patients with localized (not widespread) refractory disease.

For transplant-ineligible patients, RT can be used to treat localized disease causing pain or other complications. In a study of 60 patients receiving RT for remaining cancer after R-CHOP, only 10 patients relapsed within 4 years. In another study, patients with bulky (tumors larger than 5 cm) refractory disease received RT with chemotherapy. 1 year later, about 50% of patients achieved local disease control.

For patients with isolated relapse in the brain, RT can improve long-term survival. In a study of 113 patients with widespread NHL, 23% received chemotherapy plus whole-brain RT and 30% received whole-brain RT only. Survival rates were 23% (3+ years), 16% (4+ years), and 11% (5+ years). RT can also be an effective salvage treatment for patients that relapse or do not respond to chemotherapy for brain tumors. In one study, the average overall survival (OS; time from treatment until death of any cause) after whole-brain RT was 10.9 – 16 months.

For patients with primary mediastinal large B-cell lymphoma (PMBL), RT can also improve survival outcomes. In one study with 97 patients treated with chemotherapy with or without RT, only 10% had disease progression or relapse. Patients who also received SCT remained in remission.

The authors concluded that RT can improve outcomes and disease control for patients with localized disease if given around the time of an SCT, or as local disease control for transplant-ineligible patients.

Little data is available about the long-term effects of RT combined with new therapies, such as brentuximab vedotin (Adcetris) or ibrutinib (Imbruvica). The authors recommend limiting the use of RT with these agents due to unknown side effects or interactions with RT.