Interim positron-emission tomography (PET) may predict survival, but intensifying treatment based on PET may not improve therapeutic outcomes among patients with aggressive non-Hodgkin lymphoma (NHL), according to a study published in the Journal of Clinical Oncology.1

An important pretreatment factor that predicts survival among patients with NHL is treatment response; being able to identify which patients would respond to or fail standard therapies allows for early adjustment in treatment and improves outcomes. A previous study demonstrated that interim PET using [18F]flurodeoxyglucose may be able to predict outcomes for this patient population.

In the phase 3 Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas (PETAL) study ( Identifier: NCT00554164), researchers evaluated the outcomes of 862 patients with newly diagnosed, aggressive NHL. Patients were treated with 2 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), then underwent a PET scan; PET-positive patients were randomly assigned to undergo 6 more cycles of R-CHOP or 6 blocks of a treatment protocol for Burkitt lymphoma. PET-negative patients with CD20-positive lymphomas were randomly assigned to receive 4 additional cycles of R-CHOP or the same treatment with 2 more doses of rituximab.

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One-hundred eight (12.5%) patients and 754 (87.5%) patients had positive and negative interim PET results, respectively.

Among patients with positive results, there was no significant difference in 2-year event-free survival (EFS) rates between patients who continued R-CHOP treatment (42.0%; 95% CI, 28.2-55.2) or switched to the Burkitt protocol (31.6%; 95% CI, 19.3-44.6) (P = .1229).

Of the patients who had negative PET-scans, 255 underwent random assignment. The EFS rate was 76.4% (95% CI, 68.0-82.8) among patients who remained on R-CHOP compared with 73.5% (95% CI, 64.8-80.4) among patients who received R-CHOP plus 2 additional doses of rituximab (P = .8305).

The authors concluded, “interim PET scanning is a powerful tool with which to distinguish chemotherapy sensitive from chemotherapy resistant lymphomas,” and that “whether interim PET-positive patients may be candidates for immunologic treatment approaches, such as immunomodulation, checkpoint inhibition, or chimeric antigen receptor T cells, requires additional investigation.”


  1. Duhrsen U, Muller S, Hertenstein B, et al. Positron emission tomography-guided therapy of aggressive non-Hodgkin lymphomas (PETAL): a multicenter, randomized phase III trial [published online May 11, 2018]. J Clin Oncol. doi: 10.1200/JCO.2017.76.8093