The impact of radiotherapy dose and other treatment-related and clinical factors on in-field control in stage I and II non-Hodgkin's lymphoma

Purpose/Objective: To assess local (in-field) disease control, identify pot ential prognostic factors, and elucidate the optimal radiotherapy dose in v arious clinical settings of Stage I and II nonHodgkin's lymphoma (non-CNS). Materials & Methods: A total of 285 consecutive patients with Stage I and I I non-Hodgkin's lymphoma were treated with curative intent, including 159 w ith radiotherapy (RT) alone and 126 with combined-modality therapy (CMT). O f these, 72 patients had low-grade lymphomas (LGL), 92 had intermediate or high-grade lymphomas (I/HGL), and 21 had unclassified lymphomas. Clinical a nd treatment variables with potential prognostic significance for in-field disease control, freedom from relapse (FFR), and absolute survival (AS) wer e evaluated by univariate and multivariate analyses. Results: The 5-, 10-, and 20-year actuarial AS rates were 73%, 46%, and 33% for patients with LGL and 64%, 44%, and 18% for patients with I/HGL, respe ctively, The 5-, 10-, and 20-year actuarial FFR rates were 62%, 59%, and 49 % for patients with LGL and 66%, 57%, and 57% for patients with I/HGL, resp ectively. Significant prognostic factors identified by the multivariate ana lysis were age, tumor size, and histology for AS; tumor size and treatment for FFR; and only tumor size for in-field disease control. There were 95 to tal failures, with only 12 occurring infield. Most failures (65%) were in c ontiguous unirradiated sites. All 4 in-field failures in patients with LGL occurred after RT doses < 30 Gy, although none occurred in 10 patients with small-volume LGL of the orbit treated with doses < 30 Gy. The 8 in-field f ailures in patients with I/HGL were distributed evenly throughout the RT do se range; 5 occurred in patients treated with CMT, all with tumors > 6 cm, and 4 with less than a complete response (CR) to chemotherapy. Conclusion: Our analysis suggests that the overwhelming problem in the trea tment of non-Hodgkin's lymphoma is not in-field failure but, rather, failur e in contiguous unirradiated sites. A dose of 20-25 Gy may be sufficient fo r small-volume LGL of the orbit. A dose of 30 Gy is sufficient for LGL in g eneral, as well as for patients with nonbulky (less than or equal to 6 cm) I/HGL treated with CMT who have a CR. However, patients with I/HGL treated with CMT for tumors > 6 cm and/or without a CR may benefit from doses great er than or equal to 40 Gy. (C) 1999 Elsevier Science Inc.