Indolent non-Hodgkin's lymphoma (INHL) and chronic lymphocytic leukemia (CLL) are highly sensitive to radiotherapy (RT). Previous retrospective studies have shown high response rates after local palliative RT of 4 Gy in 2 fractions, which prompted this prospective Phase II trial of the palliative effect of this regimen in patients with disseminated INHL or CLL.

Twenty-two patients (11 men, 11 women, median age 62 years, range 30-89) with disseminated INHL (n = 15) or CLL (n = 7) were treated with local low-dose RT, 2 Gy x 2 within 3 days, with the aim of achieving palliation from localized lymphoma masses. The patients were treated to a total of 31 different sites. Seventeen patients had previously been treated with chemotherapy. The median observation time after the start of RT was 8 months (range 3-26).

All patients and all irradiated sites were assessable for response. Of the 22 patients, 18 responded to the treatment, corresponding to an overall response rate (RR) of 82%; 12 patients (55%) achieved a complete response (CR), 5 patients (22%) a partial response (PR), and 1 patient had a CR at three sites and a PR at one site. Of the 31 irradiated sites, 27 responded to treatment, corresponding to an overall RR of 87%; in 20 sites (65%) a CR was achieved and in 7 sites (22%) a PR. Patients with disseminated INHL had an overall RR of 87% (74% CR, 13% PR); patients with CLL had an overall RR of 71% (29% CR, 42% PR). The median duration of response was estimated at 22 months. None of the patients had significant side effects from the treatment.

Low-dose RT (4 Gy in 2 fractions) is a highly effective palliative treatment of localized lymphoma masses in patients with disseminated INHL and CLL. The treatment has minimal side effects.