['To determine in a Phase I study the maximum tolerated dose of weekly gemcitabine concurrent with radiotherapy in locally advanced non-small-cell lung cancer (NSCLC), as well as the relationship between the volume of the esophagus irradiated and severe esophagitis.', 'Twenty-one patients with Stage III NSCLC received gemcitabine initially at 150 mg/m(2)/wk over 7 weeks concurrently with chest radiotherapy to 63 Gy in 34 fractions. The first 9 patients underwent treatment with two-dimensional (2D) radiotherapy; the remaining 12 patients, with three-dimensional conformal radiotherapy (3D-CRT) and target volume reduced to clinically apparent disease. Consolidation was 4 cycles of gemcitabine at 1000 mg/m(2)/wk and cisplatin 60 mg/m(2).', 'In the 2D group, the dose-limiting toxicity, Grade 3 esophagitis, occurred in 3 of 6 patients in the 150-mg/m(2)/wk cohort and 2 of 3 patients in the 125-mg/m(2)/wk cohort. No cases of Grade 3 esophagitis occurred at these doses in the 3D group. At gemcitabine 190 mg/m(2)/wk, 2 of 6 patients in the 3D cohort had Grade 3 esophagitis. The mean percentages of esophagus irradiated to 60 Gy were 68% in the 2D cohort and 18% in the 3D cohort.'] Is dose escalation of gemcitabine possible with concurrent chest three-dimensional rather than two-dimensional radiotherapy : a phase I trial in patients with stage III non-small-cell lung cancer?