149 External-beam boost prior to totalbody irradiation in rflapsed NHL transplant patients

Abstract

PURPOSE: To determine the impact of an external beam boost (EBB) on the outcome, relapse pattern and normal tissue toxicities of patients undergoing total-body irradiation (TBI) prior to bone marrow transplantation (BMT) for relapsed NHL. MATERIALS AND METHODS: Between 1982 and 1994, 299 patients at our institution underwent BMT for relapsed NHL. Patients underwent induction chemotherapy (CT) followed by conditioning with cyclophosphamide and 12 Gy TBI delivered in 6 fractions over 3 days. A total of 77 patients had persistent gross disease, defined as 2 cm or greater, after induction CT and received an EBB prior to BMT (EBB cohort). The median EBB dose was 28.8 Gy (range, 5-63), the median field size was 13 cm{sup 2} (range, 5-29.4) and the median time from EBB to BMT was 3 weeks (range, 1-20). A total of 222 patients were free of measurable disease or had disease measuring =} 25% of one lung, or {>=} 15% of both lungs irradiated. Median EBB dose to the partially irradiated lung was 37.2 Gy (range, 16-63). Seven of the 26 patients receiving thoracic radiation (27%) developed symptomatic radiation pneumonitis. Symptoms have resolved in 4 patients and 3 patients have died of pulmonary complications. A total of 21 patients had abdominal radiation; 9 of these patients had direct kidney irradiation, defined as 10% or greater of total kidney volume. The median EBB dose to the partially treated kidney was 24 Gy. None of the 9 patients who received direct kidney irradiation have developed signs of kidney injury, although 1 of the 21 patients who received abdominal radiation developed a hemolytic uremia syndrome. Six patients had {>=} 50% of the heart irradiated to a median EBB dose of 37.8 Gy (range, 32-47.8). One patient developed a pericardial effusion and constrictive pericarditis after BMT while on IL-2 therapy; this patient died of respiratory causes (included in the pulmonary complication group above). CONCLUSIONS: Patients with recurrent lymphoma with gross residual disease after reinduction chemotherapy (defined as {>=} 2cm in size in this study) have a poor prognosis following BMT. In an attempt to improve the outcome of these patients, an external beam boost was given to sites of residual gross disease prior to BMT. The efficacy of this treatment remains uncertain. Caution must be exercised when using this approach to treat residual thoracic disease, as there is a high risk of associated radiation pneumonitis. However, for patients with resistant thoracic disease, external beam boost followed by BMT may offer the only potential for cure.