Report of an international workshop to standardize response criteria for non-Hodgkin's lymphomas

Standardized guidelines for response assessment are needed to ensure compar ability among clinical trials in non-Hodgkin's lymphomas (NHL). To achieve this, two meetings were convened among United States and international lymp homa experts representing medical hematology/oncology, radiology, radiation oncology, and pathology to review currently used response definitions and to develop a uniform set of criteria for assessing response in clinical tri als. The criteria that were developed include anatomic definitions of respo nse, with normal lymph node size after treatment of 1.5 cm in the longest t ransverse diameter by computer-assisted tomography scan. A designation of c omplete response/unconfirmed was adopted to include patients with a greater than 75% reduction in tumor size after therapy bur with a residual mass, t o include patients - especially those with large cell NHL - who may not hav e residual disease, Single-photon emission computed tomography gallium scan s are encouraged as a valuable adjunct to assessment of patients with large -cell NHL, but such scans require appropriate expertise. Flow cytometric, c ytogenetic, and molecular studies are not currently included in response de finitions. Response Kites may be the most important objective in phase II t rials where the activity of a new agent is important and may provide suppor t for approval by regulatory agencies. However, the goals of most phase III trials are to identify therapies that will prolong the progression-free su rvival, if not the overall survival, of the treated patients, We hope that these guidelines will serve to improve communication among investigators an d comparability among clinical trials until clinically relevant laboratory and imaging studies are identified and become more widely available. (C) 19 99 by American Society of Clinical Oncology.