340P - The role of CT scans and laboratory tests for surveillance in patients with diffuse large B cell lymphoma who achieved complete remission after first-line chemotherapy

Background

The optimal follow-up strategy for the detection of relapse in patients with diffuse large B-cell lymphoma (DLBCL) has not been clarified. In this report, we assess the role of laboratory tests and CT for surveillance and investigate the risk factors for recurrence.

Methods

We reviewed the clinical records of patients who achieved CR by PET-CT after received R-CHOP like regimen in our hospital for DLBCL between February 2008 and February 2022. Clinical evaluation post treatment was done every 3-6 months in the first 2 years, and every 6–12 years in the 3 coming years.

Results

A total of 324 patients were eligible for inclusion in this study. The median duration of follow-up for surviving patients was 4.3 years. The cumulative incidence of relapse without death at 2 and 5 years was 13.3% and 21.6%. Overall, 1453 CT scans were carried out through surveillance. The total of 64 patients relapsed within the observation period. Of these, 19 patients were detected to have recurrence on surveillance CT scans. On univariate analysis, ABC-type, extranodal (EN) stites > 1 at diagnosi, and relative dose intensity (RDI) < 90% were risk factors for recurrence. On Fine-Gray regression analysis, ABC-type (HR 2.1, 95% confidence interval [95% CI] 1.1-3.7. p=0.018) and EN sites > 1 at diagnosis (HR 1.8, 95% CI 1.1-3.6. p=0.031) were independent risk factors for recurrence. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve of the surveillance value of soluble interleukin-2 (sIL-2R) (HR 0.81, 95% CI 0.72–0.90) was significantly larger than lactate dehydrogenase (LDH) (0.65, 95% CI 0.55–0.75. p=0.024). While in the normal pretreatment sIL-2R group, the AUC of the ROC curve of sIL2R was small (0.57), however, in the high pretreatment sIL-2R group, the AUC of the ROC curve of sIL2-R (0.83, 95% CI 0.74-0.91) was high. We defined the best cutoff value of the sIL2-R as 607.5 using a ROC curve in the high pretreatment sIL-2R group (Sensitivity 0.63. Specificity 0.88).

Conclusions

Routine surveillance CT scans were of limited value in detecting asymptomatic relapse. ABC-type and EN sites were independent risk factors for recurrence. The measurement of sIL-2R might be useful for surveillance.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.