Response to low-dose involved-field radiotherapy in patients with non-Hodgkin's lymphoma

Background: The purpose of this study was to analyze response to palliative low-dose involved-field radiotherapy (LD-IF-RT) (two 2-Gy fractions), explore factors predicting for response, and determine the time course to subsequent treatment. Patients and methods: Thirty-three patients with advanced or recurrent indolent non-Hodgkin's lymphoma (NHL) received LD-IF-RT to 43 sites. Response was assessed by physical examination and radiographic studies. Median follow-up for individual sites was 14 months. Fisher's exact test was used to evaluate prognostic factors for response and in-field progression. Results: Overall response was 95%. Thirty-six sites (84%) had a complete response (CR), five sites (12%) had a partial response, and two sites (5%) had progressive disease. The CR rate of head and neck sites was significantly higher than that of pelvic and/or inguinofemoral sites (95% versus 64%, P = 0.04). The CR rate was significantly higher for sites <= 40 mm than for sites > 40 mm (90% versus 56%, P = 0.04). Ten sites (23%) had in-field progression diagnosed at a median of 9 months. Sixteen patients (48%) received systemic treatment at a median of 8 months. Fourteen patients (42%) did not require additional treatment. Conclusions: LD-IF-RT for selected NHL subtypes has excellent local CR and in-field control rates and may postpone the need for systemic therapy.