In a single-institution phase II trial reported in JAMA Oncology, Pinnix et al found that response-adapted radiation therapy featuring ultra–low-dose radiation therapy was a successful strategy in patients with indolent B-cell lymphoma of the ocular adnexa.
As stated by the investigators: “Radiation therapy to doses of 24 to 36 Gy is currently used to treat indolent B-cell lymphoma of the ocular adnexa; however, ocular adverse effects are common.”
Study Details
In this study, 50 evaluable patients enrolled at The University of Texas MD Anderson Cancer Center between July 2015 and January 2021 received ultra–low-dose radiation therapy at 4 Gy in two fractions. Patients were assessed for response at 3-month intervals; those with persistent orbital lymphoma were offered an additional 20 Gy in 10 fractions to complete response-adapted treatment. The primary outcome measure of the trial was 2-year local orbital tumor control within the irradiated field.
Key Findings
At a median follow-up of 37.4 months (95% confidence interval [CI] = 33.7–52.5 months), the 2-year local tumor control rate was 89.4% (95% CI = 81.0%–98.7%). A total of 45 patients (90.0%, 95% CI = 78.2%–96.7%) had a complete response to response-adapted radiation therapy, including 44 at receipt of ultra–low-dose radiation therapy and 1 after an additional 20 Gy. No local recurrences were observed among patients with a complete response. Overall survival rate at 2 years was 98.0% (95% CI = 94.1%–100%).
A total of three patients (6%) experienced grade 1 dry eye, and one patient (2%) experienced grade 2 dry eye. No grade ≥ 3 toxic effects were observed.
The investigators concluded: “In this nonrandomized controlled trial, response-adapted ultra–low-dose [radiation therapy] for indolent orbital B-cell lymphoma resulted in reduced radiation exposure, negligible toxic effects, and excellent disease outcomes.”
Chelsea C. Pinnix, MD, PhD, of the Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, is the corresponding author of the JAMA Oncology article.
Disclosure: The study was supported by a grant from the National Cancer Institute. For full disclosures of the study authors, visit jamanetwork.com.
