Three-dimensional Conformal Radiation Therapy For Non-small Cell Lung Cancer: A Phase Ⅰ/Ⅱ Dose Escalation Clinical Study

Objective: Through clinical doses escalation obtain the maximum tolerated dose (MTD) of three-dimensional conformal radiotherapy in non-small-cell lung cancer and observe its therapeutic effect.Methods and Materials: 84 patients of stage I-III non-small-cell lung cancer use three-dimensional conformal radiotherapy (3-DCRT) and did not conduct regional lymph node preventive irradiation. The GTV start dose escalation after the CTV irradiated 60Gy (2Gy/times, 1 times/day, 5 days/week). The boost fractions were 3-11 times (2-4Gy/fraction). According to the percentage of lung volume receiving >20Gy, the patients were divided into two groups(V₂₀<25%, V₂₀ 25%～36%). The groups based on the total dose were divided into subgroup. The incidence of radioactive damage and therapeutic effect were analyzed. The criteria for cessation of further dose escalation was that more than or equal to 15%of patients developed grade 3 radiation pneumonitis (RTOG).Results : The entire groups were 84 patients. Groups V₂₀<25% were 45 patients. Groups V₂₀ 25%～36% were 39 patients. The subgroups dose level of Groups V₂₀<25%were 70Gy, 74Gy, 78Gy, 82Gy respectively. The subgroups dose level of Groups V₂₀ 25%～36% were 66Gy,70Gy,74Gy,78Gy respectively. The incidence of grade 3 radiation pneumonitis were 5%(2/39). Two cases developed grade 3 radiation pneumonitis (V₂₀ 32%,V₂₀ 36% respectively)and occurred in subgroups 78Gy. The incidence rate was 22.2%(2/9).The median survival time of the entire groups were 14 months. 1,2-year overall survival rate were 69.5%,52.8%repectively.1,2-year local control rate were 79.7%,53.6%respectively. As the dose escalated,1,2-year survival rate and local control rate was increased, but statistical tests were not significantly different(P>0.05).Conclusion: When 3-DCRT of non-small-cell lung cancer was used for increasing the local radiation dose should ponder to normal lung tissue irradiation dose and volume. The radiation dose was safely escalated using three-dimensional conformal techniques to 82Gy for patients with V₂₀ values of <25% and to 76Gy for patients with V₂₀ values of 25%～36%. However, a higher radiation dose should be prudent with V₂₀ values>30%. To escalate local dose significant for improve overall survival and local control rate need further study yet.