RECURSIVE PARTITIONING ANALYSIS OF 1592 PATIENTS ON 4 RADIATION-THERAPY ONCOLOGY GROUP STUDIES IN INOPERABLE NONSMALL CELL LUNG-CANCER

Survival outcome of 1592 analyzable patients on four Radiation Therapy Oncology Group (RTOG) studies in inoperable non-small cell lung cance r were studied utilizing a recursive partitioning analysis (RPA). This approach creates a regression tree according to prognostic variables which partitions into homogenous subsets according to survival. Four p rotocols, RTOG 83-11, 83-21, 84-03 and 84-07 were analyzed. 83-11 and 84-07 were studies utilizing irradiation with alterfractionation; 83-2 1 and 84-03 were studies evaluating thymocin with irradiation and prop hylactic cranial irradiation with thoracic irradiation respectively. N ine pretreatment variables and one treatment variable were analyzed. A djustment for radiotherapy effect was made in the accelerated treatmen t protocol (84-07). Overall, median survival for the entire group was 9.0 months with 17% alive at 2 years. Univariate analysis suggests tha t KPS, less than or equal to 70 vs. 80-100, pleural effusion, weight l oss, less than or equal to 5% vs, 5%, age, 60 + vs. < 60, T stage (T1 and T2 vs. T3 and T4) and N stage (N- vs. N+) were important prognasti c factors. Radiation dose, sex, race and histology were not univariate prognastic factors. RPA identified KPS as the most significant covari ate (median survival 5.9 mos. less than or equal to 70 vs. 9.9 mos. 80 -100). Within KPS 80-100 other splits occurred for N stage, age, weigh t loss and radiation therapy dose. KPS less than or equal to 70 split at pleural effusion only. The best overall RPA tree has four distinct classes with median survival times ranging from 3.3 to 12.6 months. Th e RPA classes were validated in an independent non-small cell lung can cer dataset. This analysis may allow more intelligent stratification a nd study-design for future RTOG trials in inoperable non-small cell lu ng cancer. (C) 1997 Elsevier Science Ireland Ltd.