RT improves outcomes of early-stage DLBCL patients

LOS ANGELES-Patients with early-stage diffuse large B-cell lymphoma (DLBCL) have improved long-term disease-free and overall survival if their first-line treatment includes radiation therapy, according to the largest outcomes study to date among this population.

"Despite a handful of published randomized trials for stage I-II diffuse large B-cell lymphoma, there is virtually no long-term outcome information for these patients, defined as greater than 5 to 7 years. Clinical trial design and standard of care treatment typically address all early-stage patients uniformly, presuming that all patients with stage I-II disease have similar relapse risks," Rachel Rabinovitch, MD, explained.

She said that outcome data are virtually nonexistent for discrete, clinically meaningful patient subsets, "and recent clinical trial data have resulted in seemingly contradictory conclusions about the role of radiotherapy, particularly in the elderly."

SEER search

In the study, presented at the 49th annual ASTRO meeting (abstract 27), Dr. Rabinovitch and her colleagues at the University of Colorado searched the SEER database for patients receiving a diagnosis of stage I, Ie, II, or IIe DLBCL between 1988 and 2003 who had follow-up of at least 6 months. A total of 13,240 patients were identified.

"We were surprised that radiotherapy was only delivered in 41% of all early-stage patients," Dr. Rabinovitch commented.

She noted that SEER indicates whether patients received radiation as part of their first treatment course, but lacks other important data, such as lactate dehydrogenase (LDH) level, performance status, comorbidities, and systemic therapy.

In a univariate analysis, receipt of radiation therapy was associated with a significantly higher 15-year rate of disease-specific survival (70% vs 65%). In addition, older patients treated with radiation had significantly higher rates of disease-specific survival and overall survival than their counterparts not treated with radiation-regardless of whether the cutoff for being older was set at 60 years or 70 years of age.

In a multivariate analysis, receipt of radiation therapy remained significantly associated with better long-term outcomes (see Table). When patients were stratified by stage and age, the 15-year rate of disease-specific survival ranged from 53% (among patients older than 60 with stage II disease) to 82% (among patients younger than age 60 with stage I disease).

"These data, not available elsewhere in the literature, demonstrate that all early-stage DLBCL patients are not the same," Dr. Rabinovitch commented.

Although it is probable that the patients in SEER who did not receive radiation therapy included a higher proportion of patients with poor Karnofsky performance scores or other poor prognostic factors, she said, "it is unlikely in our estimate that this alone accounts for the differences observed."

The SEER analysis "supports clinical trial data showing that first-line therapy that includes radiation results in superior outcomes-even in the elderly," she concluded. The great variability in disease-specific survival among patient subgroups, all with early-stage disease, she said, "argues for the importance of developing tailored therapies based on relapse risk rather than treating all patients with localized disease uniformly."