820P - Second primary malignancies and disease transformation in symptomatic patients with Waldenstrom’s macroglobulinemia: Outcomes of a population-based analysis

Background

Waldenström's Macroglobulinemia (WM) presents heterogeneous clinical presentation and prolonged course, during which a second primary malignancy (SPM) or transformation to high grade lymphoma may occur post treatment initiation.

Methods

Symptomatic patients with WM were prospectively enrolled. The incidence of an SPM and the disease transformation post treatment initiation were recorded.

Results

668 patients were enrolled [median follow up: 186 months, median age: 71 years, males: 54%, 314 (47%) have died]. Primary treatment was rituximab-based in 63%, contained alkylating agents in 76%, a nucleoside analogue in 2%, proteasome inhibitors in 5% and Bruton’s tyrosine kinase (BTK) inhibitors in 10%. 58 patients (8.7%) were diagnosed with an SPM [prostate (22%), lung (21%), colon (9%), stomach (7%), pancreas (5%), head and neck (7%), central nervous system (7%), non-melanotic skin tumors (5%), skin melanoma (5%), ovarian (2%), thyroid (2%), hematologic malignancies (10%)]. The median time from treatment initiation to the diagnosis of an SPM or to transformation was 54 months. The incidence rate (IR) of an SPM was 0.008 per person-years. The cumulative incidence (CI), accounting for death due to WM or other causes as a competing event, at 5 and 10 years was 3.6% and 6.6%. The risk of death from WM or other causes was 22% and 45%, respectively. The IR of an SPM was higher in men (p=0.067), but no difference was recorded concerning the age or the agent used. 23 (3.4%) transformations were identified. The IR for transformation was 0.004 per person-years. The CI for transformation, accounting for death of any cause as a competing event, was 2.2% and 3.6% at 5 and 10 years respectively. The presence of anemia (hemoglobin<11.5gr/dl) at the time of diagnosis was associated with increased risk of transformation (p=0.02). The use of rituximab as a primary treatment decreased transformation risk (p=0.04).

Conclusions

The incidence of a SPM in symptomatic patients with WM post treatment initiation was 8.7%. Transformation to high grade lymphoma was 3.4%. This data emphasizes the need for screening for the most common malignancies among patients with WM, due to the prolonged survival of the disease.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.