Radiotherapy May Boost Survival for Certain Patients With DLBCL

Radiotherapy of cancer

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Patients with diffuse large B-cell lymphoma (DLBCL) who have a metabolic partial response (mPR) to chemotherapy on interim PET (iPET) scans may benefit from consolidative radiotherapy, according to a new report.

The investigators, however, cautioned that their study was based on a small sample size and thus the findings would need to be replicated on a larger scale. The report was published in Cancer Diagnosis & Prognosis.

For most patients with DLBCL, the R-CHOP chemotherapy regimen of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, is an effective first-line treatment, wrote the study authors. Still, about one-third of patients will not achieve remission with R-CHOP, and these patients face a poor prognosis, the authors said. For such patients, radiotherapy is a potential treatment option, but they noted the data on the efficacy of consolidative radiotherapy is mixed. DLBCL is a heterogenous cancer type, and many patients suffer declines associated with radiation-related toxicity, they said. However, the authors added that radiotherapy is a worthwhile treatment for some patients, especially with recent advancements in the techniques.

“Given recent developments in radiotherapy techniques, current treatment strategies employing smaller target volume contours and radiation dose-reduction therapy are anticipated to further diminish radiation-related toxicities,” they wrote.

One way to track patients’ responses to therapy is F-18 fluorodeoxyglucose (FDG) PET/CT imaging, the authors said. They noted that patients with DLBCL who test negative on iPET scans tend to have superior outcomes to those who have positive iPET scans. Yet, they said there is little in the way of scientific evidence to suggest whether using iPET to guide radiotherapy leads to improved outcomes among people with DLBCL.

The authors set about reviewing 107 patients with DLBCL who were treated with R-CHOP at their medical center between 2012 and 2016. The investigators wanted to compare outcomes based on iPET results and whether patients received radiotherapy. Sixty-one patients in the initial pool were ultimately excluded from the final analysis because iPET results were unavailable, and others were excluded because they had double primary cancer or did not complete R-CHOP, among other factors.

Among the 46 patients included in the final analysis, the median follow-up was 65.9 months. Patients who achieved a metabolic complete response (mCR; n = 29) had better rates of overall survival, recurrence-free survival, and freedom from disease progression (FFDP) compared with the 17 patients with a mPR, the investigators found. For instance, the 5-year FFDP rate among the mCR group was 85.6%, while the rate in the mPR group was 44.2%.

However, when the investigators looked specifically at the 17 patients with mPR, they found that the 10 patients who underwent consolidative radiotherapy had improved outcomes vs patients who did not, although the improvement did not reach statistical significance.

They auythors said their results support the idea that consolidative radiotherapy is beneficial for select patients.

“We contend that the decision to proceed with radiotherapy based on iPET scan findings has the potential to enhance clinical outcomes, particularly in individuals who do not achieve complete mCR on iPET CT,” they wrote.

They said given the small sample size, they believe their findings should be used as the “foundation” for a larger, prospective, randomized trial.

Reference

Yu J, Jung SU, Choi JH, Jun S, Lee HS, Kim D. Clinical outcomes in patients with DLBCL treated with R-CHOP according to radiotherapy and interim PET response. Cancer Diagn Progn. 2024;4(2):172-181. doi:10.21873/cdp.10304