Low-Dose Radiation Elicits Responses in Orbital B-Cell Lymphoma

An expert emphasized that treatment for cancer should not be worse than the cancer itself.

Ultralow-dose radiation therapy is an effective treatment strategy for some patients with indolent orbital B-cell lymphoma, a rare blood cancer that occurs in the eye, researchers have reported.

The researchers, who published their findings in JAMA Oncology, showed that in a phase 2 trial of response-adapted ultralow-dose radiation therapy, the two-year local control (no progression of the primary cancer) rate was 89.4%, with 90% of the study’s 50 patients experiencing a complete response (the disappearance of cancer) and no grade 3 (severe) or higher side effects.

Under the trial, instead of the standard of care radiation dose of 24 Gray (Gy; measurement for radiation therapy), patients were treated with 4 Gy of radiation in two fractions and assessed at three-month intervals. Patients experiencing persistent orbital lymphoma were offered 20 Gy of radiation in 10 fractions as part of response-adapted treatment.

Researchers reported that 44 patients experienced a complete response with ultralow-dose radiation, and an additional patient achieved a complete response after receiving 20 additional Gy. No patients who achieved a complete response experienced a local recurrence.

“Radiation therapies had a role for treating indolent or low-grade B-cell lymphoma of the orbit for some time,” said Dr. Chelsea C. Pinnix, Associate Professor, Department of Radiation Oncology, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center in Houston and co-author of the study, in an interview with CURE®.

“In the past, we used much higher doses of 40 to 50 Gy. … The standard dose now is considered to be 24 Gy, that's a moderate dose of radiation,” Pinnix said. “But even with that moderate dose, we observed that patients can still develop side effects from the radiation. And so, the radiation is very effective at helping to eradicate the disease and achieving what we call a complete response. More than 90% of patients who have the standard dose of 24 Gy will get that complete response.

“But, it's not uncommon for patients to experience some ocular side effects that may be long-term. The most common would be cataract, which can be taken care of surgically, it's a common procedure, cataract removal, but [there’s] also dry eye and that can also be problematic long-term for patients that may require long-term use of different lubricants for the eye, the eye drops and things like that. With that in mind, we are trying to figure out how can we help to mitigate some of those side effects without compromising the excellent disease outcomes that we see after radiation.”

The majority of the study’s 50 patients (32 patients, or 64%) had mucosa-associated lymphoid tissue (MALT) lymphoma, researchers noted. Most patients also had stage 1 disease (31, or 62% of patients) and were newly diagnosed (36, or 72%).

The study, as Pinnix explained, is part of a movement towards being mindful of patients’ quality of life while treating cancer.

“As oncologists, we continue to evolve,” Pinnix said. “And I love that we have increased awareness of the patient voice and the patient experience. And it's no longer where we see a patient and we do the treatment, and we're happy achieving that complete response and then we pat ourselves on the back and move on. But instead — and this is where seeing patients and follow-up is really important — we're trying to understand the side effects that patients are experiencing, how this can complicate their quality of life and decrease quality of life, and that's especially important in diseases like this.

“So, for instance, … MALT lymphoma, it's very rarely life-threatening. Even when patients in the past were treated with higher doses of radiation, 25 to 30 Gy, they developed relapse outside of the radiation field [where] it was treated, and long-term follow-up shows that those patients do not pass away due to their disease. And so, it's really important that we keep in mind, we don't want our treatments to be worse than the disease itself.”

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