PROMISING SURVIVAL WITH 3-DIMENSIONAL CONFORMAL RADIATION-THERAPY FORNONSMALL CELL LUNG-CANCER

Purpose: Local failure is a major obstacle to the cure of locally adva nced non small-cell lung cancer. Three-dimensional conformal radiation therapy (3-DCRT) selects optimal treatment parameters to increase dos e to tumor and reduce normal tissue dose, potentially representing an enhancement of the therapeutic ratio of radiation therapy for lung can cer. We performed this analysis of 45 non-small cell lung cancer patie nts treated with 3-DCRT alone, to evaluate the ability of computer der ived lung dose volume histograms to predict serious pulmonary toxicity , to assess the feasibility of this approach, and to examine the resul ting survival. Methods: There were 28 males (62%) and 17 females (38%) . The median age was 65 (range: 38-82). Tumor stage was Stage I/II in 13%, IIIa in 42%, and IIIb in 44%. The histology was squamous in 44%, adenocarcinoma in 36%, and other non-small cell histologies in the oth ers. Only 47% of patients. had combined favorable prognostic factors ( i.e. KPS less than or equal to 80, and less than or equal to 5% wt. lo ss). The median dose of radiation to gross disease was 70.2 Gy (range: 52.2-72 Gy) delivered in fractions of 1.8 Gy, 5 days per week. Result s: Seven patients did not complete 3-DCRT due to disease progression o utside the port. Follow-up data are mature: the median follow up of th e 6 survivors is 43.5 months (35-59). Thoracic progression occurred in 46%. Median survival (all 45 patients.) is 15.7 months and survival i s 32% at 2 years and 12% at 59 months. Pulmonary toxicity greater than or equal to grade 3 occurred in 9% of patients. Dose volume histogram s were available in 31 patients and showed a correlation between risk of pulmonary toxicity and indices of dose to lung parenchyma. Grade 3 or higher pulmonary toxicity occurred in 38% (3/8) of patients with >3 0% of lung volume receiving greater than or equal to 25 Gy, versus 4% (1/23) of patients with less than or equal to 30% lung receiving great er than or equal to 25 Gy (P = 0.04). Grade 3 or higher pulmonary toxi city occurred in 29% (4/14) of patients with a predicted pulmonary nor mal tissue complication probability of 12% or higher versus 0% (0/17) in patients with a predicted probability of less than 12% (P = 0.03). Conclusions: Despite adverse prognostic criteria median survival is en couraging and may be higher than some combined modality approaches. Do se volume histogram parameters may be useful to determine the maximum dose for individual patients and thereby permit avoidance of toxicity. (C) 1997 Elsevier Science Ireland Ltd.