Limited-Stage Diffuse Large B-Cell Lymphoma Treated With Abbreviated Systemic Therapy and Consolidation Radiotherapy: Involved-Field Versus Involved-Node Radiotherapy

For limited-stage diffuse large B-cell lymphoma (DLBCL), treatment decisions are often influenced by toxicity profiles. One strategy that minimizes chemotherapy-induced toxicities is abbreviated chemotherapy plus consolidation involved-field radiotherapy (IFRT). Involved-node radiotherapy (INRT) is a new concept to DLBCL, aimed to reduce radiotherapy-induced toxicities. We retrospectively review the long-term outcomes of limited-stage DLBCL treated with abbreviated systemic therapy and radiotherapy focusing on field size: IFRT versus INRT. The British Columbia Cancer Agency Lymphoid Cancer Database was used to identify patients diagnosed with limited-stage DLBCL (stage I/II, without B-symptoms; bulk < 10 cm) from 1981 to 2007. Patients were prescribed 3 cycles of chemotherapy plus IFRT (1981-1996) or INRT≤5 cm (1996-2007), defined as INRT to the prechemotherapy involved nodes with margins ≤ 5 cm. A total of 288 patients were identified: 56% were aged >60 years, 34% had stage II disease, 55% had extranodal disease, 19% had elevated lactate dehydrogenase levels, and 15% received rituximab. The two radiotherapy groups were IFRT (138 patients; 48%) and INRT≤5cm (150 patients; 52%); median follow-up was 117 and 89 months, respectively. Distant relapse was the most common site of failure in both groups. After INRT≤5 cm, marginal recurrence was infrequent (2%). Time to progression (P = .823), progression-free survival (P = .575), and overall survival (P = .417) were not significantly different between the radiotherapy cohorts. Radiotherapy field size was not a significant prognostic factor on multivariate analyses. This research is the first known body of work to apply the concept of INRT to limited-stage DLBCL. Reducing the field size from IFRT to INRT≤5 cm maintains a low marginal recurrence risk with no impact on overall outcome.