Stereotactic, high single-dose irradiation of stage I non-small cell lung cancer (NSCLC) using four-dimensional CT scans for treatment planning

We reviewed response rates, local control, survival and side effects after non-fractionated stereotactic high single-dose body radiation therapy for lung tumors. Forty patients with stage I non-small cell lung cancer (NSCLC) underwent radiosurgery involving single-dose irradiation. The standard dose prescribed to the isocenter was 30Gy with an axial safety margin of 10mm and a longitudinal safety margin of 15mm. The planning target volume (PTV) was defined using three CT scans with reference to the phases of respiration so that the movement span of the clinical target volume (CTV) was enclosed. The volume of the bronchial carcinomas varied from 4.2 to 130cm(3) (median: 19.5cm(3)), and the PTV derived from four-dimensional CT (4D-CT) scans using image fusion ranged from 15.6 to 390.5cm(3) (median: 101cm(3)). Tumor size ranged from 1.7 to 10cm at largest focuses. Follow-up periods varied from 6.0 to 61.5 months (median: 20 months). We observed three local tumor recurrences, resulting in an actuarial local tumor control of 81% at 3 years. With the exception of two rib fractures, no serious late toxicity was observed. The overall survival probability rates were: 2 years: 66%, 3 years: 53% (median overall survival: 37 months). Cancer-specific survival probability was: 2 years: 71%, 3 years: 57%. Non-fractionated high single-dose SBRT for NSCLC is more convenient for the patient and less time-consuming than hypofractionated SBRT, but data dealing with this method are still scanty. This alternative treatment results in favourable local control and acceptable toxicity.