Prognostic factors for local control of stage I non-small cell lung cancer in stereotactic radiotherapy: a retrospective analysis

Abstract

BackgroundThe purpose of this study is to investigate the prognostic factors of stereotactic radiotherapy for stage I NSCLC to improve outcomes.MethodsStage I non-small cell lung cancer patients who were treated with stereotactic radiotherapy between 2005 and 2009 at our hospital were enrolled in this study. The primary endpoint was local control rate. Survival estimates were calculated from the completion date of radiotherapy using the Kaplan-Meier method. The prognostic factors including patients’ characteristics and dose-volume histogram parameters were evaluated using Cox’s proportional hazard regression model.ResultsEighty patients (81 lesions) treated with 3 dose levels, 48 Gy/4 fractions, 60 Gy/8 fractions and 60 Gy/15 fractions, were enrolled in this study. Median follow-up was 30.4 months (range, 0.3 – 78.5 months). A Cox regression model showed T factor (p = 0.013), biological effective dose calculated from prescribed dose (BED10) (p = 0.048), and minimum dose for PTV (p = 0.013) to be prognostic factors for local control. Three-year overall survival rate and local control rate were 89.9% (T1: 86.8%, T2: 100%) and 89.0% (T1: 97.9%; T2: 64.8%), respectively. When the 3-year local control rates were examined by prescribed doses, they were 100% for the dose per fraction of 48 Gy /4 fractions (105.6 Gy BED10), 82.1% for 60 Gy/8 fractions (105 Gy BED10), and 57.1% for 60 Gy/15 fractions (84 Gy BED10). The median value of the minimum dose for PTV (%) was 89.88 (%), and the 3-year local control rates were 100% in those with the minimum dose for PTV (%) ≥ 89.88% and 79.2% in those with the minimum dose for PTV (%) < 89.88%.ConclusionsOur results suggest that T factor, BED10, and minimum dose for PTV influence the local control rate. Local control rate can be improved by securing the minimum dose for PTV.

Correlation Between Tumor Size and Blood Volume in Lung Tumors: A Prospective Study on Dual-Energy Gemstone Spectral CT Imaging

“…The mean values of the average water density for solid type tumors and GGO type tumors were 996.6 and 731.5 mg/cm 3 , respectively (P < 0.05). The average CT value and the average water density were clearly reduced in the tumors of GGO type compared with those of solid type, as shown in Fig.…”

“…SBRT is expected to be one of the treatment alternatives to surgery for early-stage lung cancer [2]. Several available reports have focused on good tumor control by SBRT [3][4]. Although the local control rate for a T1 tumor is~90%, the local control rate for a T2 tumor is poor in comparison [5][6][7].…”

Feasibility and Efficacy of Adaptive Intensity Modulated Radiotherapy Planning according to Tumor Volume Change in Early Stage Non-small Cell Lung Cancer with Stereotactic Body Radiotherapy

“…Dmin was significantly reduced by approximately 8.3%. Shirata et al 25) reported that minimal dose could affect local control in stage I NSCLC with SBRT. The 3-year local control rates were 100% in patients with Dmin for PTV of more than 89.88% versus 79.2% in those with dose for PTV less than 89.88%.…”

Dosemetric Parameters Predictive of Rib Fractures after Proton Beam Therapy for Early-Stage Lung Cancer

“…However, the converse is observed in patients with primary lung cancer associated with central lesions. Therefore, several prescribed doses are necessary to treat NSCLC (McGarry et al 2005;Nagata et al 2005;Timmerman et al 2006;Xia et al 2006;Baumann et al 2009;Shirata et al 2012).…”

“…On the other hand, small-cell lung cancer is characterized by the early development of widespread metastases; therefore, with a few exceptions, local surgery is not the standard treatment. Stereotactic radiotherapy (SRT) is the established treatment for early-stage lung cancer that is inoperable because of medical contraindications, and it achieves good local control (McGarry et al 2005;Nagata et al 2005;Timmerman et al 2006;Baumann et al 2009;Shirata et al 2012). However, desired dose applications within target volumes are limited because of the proximity to critical normal tissues.…”