A five‐field conformal technique with three‐dimensional radiation therapy treatment planning (3‐DRTP) has been shown to permit better definition of the target volume for lung cancer, while minimizing the normal tissue volume receiving greater than 50% of the target dose. In an initial study to confirm the safety of conventional doses, we used the five‐field conformal 3‐DRTP technique. We then used the technique in a second study, enhancing the therapeutic index in a series of 42 patients, as well as to evaluate feasibility, survival outcome, and treatment toxicity. Forty‐two consecutive patients with nonsmall‐cell lung carcinoma (NSCLC) were evaluated during the years 1993–1997. The median age was 60 years (range 34–80). The median radiation therapy (RT) dose to the gross tumor volume was 6,300 cGy (range 5,000–6,840 cGy) delivered over 6 to 6.5 weeks in 180–275 cGy daily fractions, 5 days per week. There were three patients who received a split course treatment of 5,500 cGy in 20 fractions, delivering 275 cGy daily with a 2‐week break built into the treatment course after 10 fractions. The stages of disease were II in 2%, IIIA in 40%, IIIB in 42.9%, and recurrent disease in 14.3% of the patients. The mean tumor volume was 324.14 cc (range 88.3–773.7 cc); 57.1% of the patients received combined chemoradiotherapy, while the others were treated with radiation therapy alone. Of the 42 patients, 7 were excluded from the final analysis because of diagnosis of distant metastasis during treatment. Two of the patients had their histology reinterpreted as being other than NSCLC, 2 patients did not complete RT at the time of analysis, and 1 patient voluntarily discontinued treatment because of progressive deterioration. Median follow‐up was 11.2 months (range 3–32.5 months). Survival for patients with Stage III disease was 70.2% at 1 year and 51.5% at 2 years, with median survival not yet reached. Local control for the entire series was 23.3 ± 11.4% at 2 years. However, for Stage III patients, local control was 50% at 1 year and 30% at 2 years. Patients who received concurrent chemotherapy had significantly improved survival (P = 0.002) and local control (P = 0.004), compared with RT alone. Late esophageal toxicity of ≥Grade 3 occurred in 14.1 ± 9.3% of patients (3 of 20) receiving combined chemoradiotherapy, but in none of the 15 patients treated with RT alone. Pulmonary toxicity limited to Grades 1–2 occurred in 6.8% of the patients, and none developed ≥Grade 3 pulmonary toxicity. Patients with locally advanced NSCLC, who commonly have tumor volumes in excess of 200 cc, present a challenge for adequate dose delivery without significant toxicity. Our five‐field conformal 3‐DRTP technique, which incorporates treatment planning by dose/volume histogram (DVH) was associated with minimal toxicity and may facilitate dose escalation to the gross tumor. Radiat. Oncol. Invest. 7:297–308, 1999. © 1999 Wiley‐Liss, Inc.
