Necessary and sufficient dose at stereotactic radiotherapy in functionally inoperable patients with non-small cell lung cancer

Objective. To improve the results of treatment of functionally inoperable patients with non-small cell lung cancer (NSCLC). Material and methods. Stereotactic body radiotherapy (SBRT) was performed in 72 functionally inoperable patients with verified NSCLC. The average age was 69 years. In 57 (79.2%) patients SBRT was performed for primary NSCLC, in 15 (20.8%) — for recurrence in the primary tumor area after surgical and/or combined treatment. Before SBRT in all patients the presence of primary or recurrent tumor was the only manifestation of cancer. SBRT was performed from single dose 8—15 Gy to total dose 40—60 Gy with active breath control (ABC) on inspiration and determination of the target position before each irradiation session. Results. 35 (48.6%) had post-radiation pneumonitis. Of them 32 (91.4%) had RTOG 1 pneumonitis. 3 (8.6%) patients with PTV volume <70 cm3 had RTOG 2 pneumonitis, two patients had RTOG 2 pneumonitis after 40 Gy total dose and one patient had RTOG 2 pneumonitis after 45 Gy. Expressed resorption — in 57 (79.2%) patients, partial resorption — in 15 (20.8%) patients. Local three-year follow-up was 100%. Cluster analysis using Mann-Whitney U-test showed that the median “optimal” ROD and SOD at peripheral localization of the target is 10 Gy — 45 Gy, at central — 8 Gy — 40 Gy, respectively. One-year and three-year cancer-specific survival rates (CSS) were 91.3% and 69.5%, one-year and three-year overall survival rates (OSR) were 84.1% and 32.2%, respectively. Conclusion. Local control, radiotherapy response rate, CSS and OSR indicate that SBRT according to the proposed technique is a safe and effective treatment option in functionally inoperable patients with both primary NSCLC and relapsed disease.