Definitive conventionally fractionated RT for early-stage NSCLC is considered reasonable non-surgical therapy but yields poor 5-year survival rates ranging from 10 to 30%.7-11 Several studies have suggested a dose-response relationship reporting a benefit to dose escalation above the standard conventionally fractionated 4,500 to 6,600 cGy. This benefit was evident in both survival and local control in these patients.10-14 Sibley, et. al., reviewed 156 medically inoperable patients with stage I NSCLC treated with primary RT at Duke University between 1980 and 1995. They reported a 5-year, cause-specific survival rate of 32%. There was a trend toward improved survival in those patients achieving local control which approached significance for higher RT doses (p = 0.07).13 At this institution, we have published a series treating 56 patients with medically inoperable NSCLC with a median dose of 70 Gy using conformal radiotherapy techniques.15 Actuarial local control rates were 69% and 63% at two- and three years of follow up, respectively. These data serve as the estimate for statistical power calculations for this trial.