The value of regional nodal radiotherapy (dose/volume) in the treatment of unresectable non-small cell lung cancer: an RTOG analysis

PURPOSE/OBJECTIVE: To evaluate whether or not the traditional practice of including all thoracic regional nodal areas in the radiotherapy volume in the treatment of unresectable lung cancer is of any therapeutic benefit. MATERIALS AND METHODS: A total of 1,705 patients from four large RTOG trials (78-11, 79-17, 83-11, 84-07) were analyzed for this purpose. Each of these trials had data on dose delivered to the nodal regions and assessment of nodal borders. The nodes were separated into mediastinal, contralateral hilar, ipsilateral hilar, and supraclavicular. Each node site was assessed for progression, defined as in-field or out-of-field, at the node site. In patients with adequate nodal field borders, the results were also analyzed according to the dose delivered. RESULTS: The majority (74%) of patients were between the age of 55 to 75. Forty-six percent of patients had KPS of 60 to 80 and 52% KPS of 90 to 100. Sixty percent of patients had a weight loss of less than 5%, and 40% had a weight loss of over 5% six months prior to diagnosis. Major variations from protocol in defining field borders (unacceptable field borders) were lowest for ipsilateral hilum ((42(727))) and the highest for mediastinal borders ((158(743))). Three groups had statistically significant differences in outcome (progression) between the per protocol and the unacceptable per protocol: ipsilateral hilar nodes (field borders), 14% versus 26% (p = 0.03); dose to mediastinal nodes in CALGB eligible patients, 9% versus 19% (p = 0.02); and ipsilateral hilar nodes (field borders) for high-dose patients assigned to greater than or equal to 69.6 Gy, 14% versus 31% (p = 0.007). CONCLUSION: These data suggest that inclusion of the ipsilateral hilar and mediastinal nodes affect outcome in unresectable non-small cell lung cancer. Exclusion of the other thoracic lymph node regions did not affect outcome in this study. These findings have important implications for combined modality therapy and three-dimensional conformal radiation therapy