Clinical Analysis Of Daily Online CBCT Images-guided Stereotactic Body Radiation Therapy For Lung Tumor

C Abstract] Objective we retrospectively analyze clinical efficacy and relevant factors of daily online CBCT images-guided stereotactic body radiotherapy (SBRT) for primary and metastatic lung tumor Methods From5/6/2009to5/24/2013,36cases of lung cancer patients were treated by stereotactic body radiotherapy (SBRT), including24cases of primary lung tumor, Metastatic lung cancer in12patients.42lesions treated including24from the primary lesion and18from metastases.9central type lesions,33peripheral type. CT Simulation includes26cases of spiral CT,10cases of4DCT。 Dose regimens:the proportion of BED10≥100Gy was85.7%(36/42),10Gyx5Fraction (BED10=100Gy) of dose regimen was the most commonly adopted, accounting for61.9%of all dose regimens. Before each delivery, CBCT was acquired and PTV/PGTV and CBCT tumors were registered by online automatic or manual methods, not setting setup threshold, sifting couch and correcting error before irradiation. Results Follow-up duration after SBRT was2-50months, the median follow-up time was21.5months, the CR rate of42lesions was38%(16/42), the CR rate of the primary lesions was50%(12/24), the CR rate of metastatic lesions22%(4/18)(P=0.067), the median time interval from the end of SBRT to starting of the CR was9months (range6to12), the median tumor BED10dose of CR lesions was100Gy (range100-115.5Gy), the size of either primary or metastatic lesions of CR was not more than3cm.For all cases,1-,2-,3-years local control rates was95.8%,88.6%,72.2%;1-,2-,3-years cancer specific survival rate was82.4%,74.3%,63.7%;1-,2-,3-years overall survival rates was77.8%,63.5%,52.6%. Univariate analysis indicated that no variant was accociated with local control, no variant was associated with overall survival by Multivariate analysis. Both Univariate and multivariate analysis showed that only tumor location variant (central type, peripheral type) was associated with cancer specific survival rate, the mean (95%confidence interval) of cancer specific survival time of the central and peripheral was21.4months (95%CI13.2to29.6),42.3months (95%CI35.7to49.0) respectively (P=0.024). Conclusion the clinical efficacy of daily online image-guided stereotactic body radiation therapy for primary or metastatic lung tumor is satisfactory.