The rates of subsequent acute myeloid leukemia (AML), melanoma, and thyroid cancer are higher since the introduction of rituximab for patients with diffuse large B cell lymphoma (DLBCL), according to a study published in the British Journal of Haematology.1

Rituximab, a monoclonal antibody that targets CD20 antigen expression in normal and malignant B cells, has improved survival rates among patients with DLBCL since its introduction in the late 1990’s. There are, however, few data about whether rituximab increases the rate of subsequent primary malignancies (SPMs) in this population.

For this study, researchers evaluated patient data from the California Cancer Registry to determine standardized incidence ratios (SIRs) for SPMs among 23,879 patients diagnosed with DLBCL before (1989-2000) and after (2001-2012) the introduction of rituximab. SIRs were compared with cancer incidence rates in the general population.

While the overall incidence of solid tumors was lower post-rituximab (SIRs of 1.08 vs 1.15 pre-rituximab), the cumulative incidence for all SPMs was higher post-rituximab (5.41% vs 4.77% pre-rituximab).

The SIR for AML in the post-rituximab era was almost twice that of pre-rituximab (8.7 vs 4.39, respectively); the cumulative incidence of AML was also higher post-rituximab (.41% vs .15%).

The SIRs and cumulative incidence rates of subsequent thyroid cancer and melanoma were also higher post-rituximab.

The rate of SPMs continued to rise for 10 years in both groups.

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The authors noted that rituximab’s mechanism of action may reduce immune surveillance, allowing for the proliferation of cancer cells. They concluded that these results “can potentially elucidate the aetiology of SPMs and guide cancer surveillance efforts among DLBCL patients diagnosed in the modern treatment era, a growing patient population that is living longer.”

Reference

  1. Tao L, Clarke CA, Rosenberg AS, et al. Subsequent primary malignancies after diffuse large B-cell lymphoma in the modern treatment era. Br J Haematol. 2017 May 25. doi: 10.1111/bjh.14638 [Epub ahead of print].