Three-dimensional conformal radiation therapy for non-small-cell lung cancer: a phase I/II dose escalation clinical trial.

PURPOSE

A prospective Phase I/II dose escalation study was conducted to determine the maximum tolerated dose (MTD) in three-dimensional conformal radiation therapy (3D-CRT) for non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

MTD would be reached via a dose escalation study. After 42 Gy/21 fractions, 4.2 weeks by conventional fractionated irradiation through anteroposterior/posteroanterior fields, the 3D-CRT technique was used as boost. The planned total dose escalation depended on lung volume irradiated. According to the percentage of lung volume receiving >20 Gy, the patients were divided into three subgroups (i.e., <25%, 25%-37%, and >37%). The scheduled dose escalation began with 69 Gy and continued to 78 Gy. The boost doses were delivered at 3 Gy per fraction, once per day, five fractions per week. Each dose level includes 5 patients. Besides radiotherapy, all patients received neoadjuvant and adjuvant chemotherapy with MVP regimen (Mitomycin, Vindesine, cis-platium). The criterion for stopping further dose escalation was > or =20% of patients with > or =RTOG Grade 3 radiation pneumonitis.

RESULTS

Between June 1999 and February 2001, 50 patients had been enrolled in this study, including 4 with Stage II disease, 31 with Stage IIIa disease, and 15 with Stage IIIb disease. The dose escalation plan has been completed. All subgroups reached the highest predetermined dose levels (i.e., 78 Gy for the <25% subgroup, 78 Gy for the 25-37% subgroup, and 75 Gy for the >37% subgroup). Although none of the subgroups developed more than 20% of >/=Grade 3 acute pneumonitis, dose escalation was terminated because long-term follow-up was needed to observe late complications. Median follow-up time (MFT) for the entire group was 18 months (6-37 months). The most common acute complication was esophagitis in 56% of patients with RTOG Grade 1-2, and in 4% with Grade 3. Acute radiation pneumonitis developed in 36% of patients with RTOG Grade 1-2. Only 1 patient had Grade 3 pneumonitis, which was in the 25-37% subgroup at 75 Gy. The hematopoietic toxicity appeared in 58% of patients with Grade 1-2, and 8% with Grade 3. As to late complications, only 30% of patients developed pulmonary fibrosis of RTOG Grade 1-2. The median survival time for the entire group was 18 months. Two-year overall survival, locoregional progression-free rate, and distant metastasis rate were 44%, 40%, and 41%, respectively.

CONCLUSIONS

Although MFT was 18 months, it had not yet been declared because a longer follow-up was needed to observe the late complications. The 2-year overall survival of 44% was very encouraging and implied that 3D-CRT combined with chemotherapy would improve the outcome for locally advanced NSCLC.