Addition of chemotherapy to radiation therapy alters failure patterns by cell type within non-small cell carcinoma of lung (NSCCL): analysis of radiation therapy oncology group (RTOG) trials

Abstract

Purpose: To evaluate the influence of cell type within non-small cell carcinoma of lung (NSCCL) on failure patterns when chemotherapy (CT) is combined with radiation therapy (RT). Methods and Materials: Data from 4 RTOG studies including 1415 patients treated with RT alone, and 5 RTOG studies including 350 patients also treated with chemotherapy (RT + CT) were analyzed. Patterns of progression were evaluated for squamous cell carcinoma (SQ) ( n = 946), adenocarcinoma (AD) ( n = 532) and large cell carcinoma (LC) ( n = 287). Results: When treated with RT alone, SQ was more likely to progress at the primary site than LC (26% vs. 20%, p = 0.05). AD and LC were more likely to progress in the brain than SQ (20% and 18% vs. 11%, p = 0.0001 and 0.011, respectively). No differences were found in intrathoracic and distant metastasis by cell type. When treated with RT + CT, AD was less likely to progress at the primary than either SQ or LC (23% vs. 34% and 40%, respectively; p = 0.057 and 0.035). AD was more likely than SQ to metastasize to the brain (16% vs. 8%, p = 0.03), and other distant sites (26% vs. 14%, p = 0.019). No differences were found in intrathoracic metastasis. LC progressed at the primary site more often with RT + CT than with RT alone (40% vs. 20%, p = 0.036). Death with no clinical progression was more likely with SQ than AD or LC for RT alone and RT + CT ( p < 0.01). Brain metastasis was altered little by the addition of CT, but other distant metastases were significantly decreased ( p < 0.001) in all cell types by the addition of CT. Conclusion: CT, although effective in reducing distant metastasis in all types of NSCCL, has different effects on the primary tumor by cell type, and has no effect on brain metastasis or death with no progression. Different treatment strategies should be considered for the different cell types to advance progress with RT + CT in NSCCL.