STEREOTACTIC RADIOTHERAPY FOR THE TREATMENT OF CLINICAL STAGE I-IIA LUNG CANCER PATIENTS. THE EXPERIENCE OF N.N. BLOKHIN NATIONAL MEDICAL RESEARCH CENTER OF ONCOLOGY

Abstract

Introduction: Nowadays the stereotactic radiotherapy (SRT) of clinical stage I-II lung cancer patients is the choice of the treatment modality for functionally inoperable patients. It shows safety and high efficiency in achieving local control. Though there is a range of unsolved issues connected with the prediction of the treatment efficiency and frequency of complications, an integration of new technologies in the planning and treatment process allows widening the search of the predictive factors. Material and methods. Since 2014, 39 patients (17 T1N0M0 patients, 22 T2N0M0 patients) with clinical stage I-IIa lung cancer have undergone SRT. The majority of patients (35) have been recognized as functionally inoperable due to the concurrent broncho-pulmonary pathology, 4 conditionally operable patients have refused an operation. 11 patients had the primary multiple tumors in their anamneses. 36 patients had a peripheral tumor. The options for the fractionation were: 10 Gy × 5 fractions (n = 26) and 7 Gy × 8 fractions (n = 13) - BED = 100 Gy. Results. The median follow-up was 26 months (range: 3-38 months). The 2-year local control was 94%. The isolated local recurrences were not registered. Overall and 2-year recurrence-free survival rate was 84% (95% CI, 70-99) and 83.2% (95% CI: 70.5-99) respectively. During the first year, 4 patients (10%) had the locoregional and distant progression and 3 of them died. 7 patients had experienced pulmonary toxicity of grade 2 or more. One patient with central tumor died from pulmonary hemorrhage (toxicity of grade 5). Grade 3 chest pain was observed in 2 patients, one of them had a rib fracture. One-factor analysis, revealed a reliable influence of the fractionation regimen (р = 0.04) and, close to reliability, the initial SUVmax level (р = 0.07) on the prognosis. A reliable relationship between the radiation toxicity level and dosimetric radiation index (V10, V5, MLD) was not registered. There was a tendency to reliable correlation with the total lung capacity indices (р = 0.058). Conclusions. A search for additional treatment efficiency and toxicity predictors of SRT treatment should include modern approaches to planning and delivery. The total dose delivery regimen and initial tumor SUVmax can be predictive efficiency factors, while the pulmonary tissue volume can be a predictive toxicity factor.