How would you treat a patient with a refractory primary splenic marginal zone lymphoma with symptomatic splenomegaly (20 cm) and a mild pancytopenia?

Prior trials of systemic therapy including alkylating agents and rituximab have failed and the patient is medically inoperable with no history of Hepatitis C. If you offer RT, what dose and target would you recommend? How often would you check a CBC and would you stop/hold treatment if the patient had worsening of cytopenia during radiation treatment?

1 Answer

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Radiation Oncology · Duke University Medical Center

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Radiation therapy is utilized in two primary settings to palliate symptoms of splenomegaly in patients with hematologic malignancies.

First, extramedullary hematopoiesis within the spleen can lead to symptomatic splenomegaly in a variety of hematologic malignancies (e.g., myelofibrosis). In this setting, cytopenias are common and irradiation of the spleen needs to be pursued with caution to avoid complications, especially leukopenia and thrombocytopenia. In such scenarios, I will often give 0.5 - 1 Gy a couple times a week, monitoring blood counts along the way, aiming to deliver a total dose of ~ 6-10 Gy.

Second, some malignancies can directly infiltrate the spleen leading to splenomegaly without extramedullary hematopoiesis. If the bone marrow is functioning and not excessively involved by the underlying hematologic disorder, cytopenias are usually not a problem. Radiation therapy can be delivered in a conventional manner using a total dose appropriate for the underlying disease.

Of course, in some scenarios, both malignant infiltration and extramedullary hematopoiesis may be present simultaneously (e.g., CLL).

Patients with splenic marginal zone lymphoma often present with cytopenias, but often these are more related to splenic sequestration than infiltration of the bone marrow by lymphoma. Marginal zone lymphoma is very sensitive to RT and often responses are fairly rapid. A dose of 4-10 Gy should provide optimal palliation. If the blood counts were OK, I would probably give 2 Gy X 2 and have the patient return to see me in 1 week with a CBC and to re-evaluate the size of the spleen by physical exam and assess improvement in symptoms. Depending upon the response, further RT could easily be administered.

Good review- Zaorsky et al. Splenic irradiation for splenomegaly: a systematic review. Cancer Treatment Reviews 2017;53:47-52