Email updates

Keep up to date with the latest news and content from Radiation Oncology and BioMed Central.

Open Access Research

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

Yuko Shirata14*, Keiichi Jingu1, Masashi Koto2, Masaki Kubozono1, Ken Takeda3, Toshiyuki Sugawara1, Noriyuki Kadoya1 and Haruo Matsushita1

Author Affiliations

1 Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan

2 Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan

3 Department of Therapeutic Radiology, Clinical Radiological Science, Course of Radiological Technology, Tohoku University School of Health Sciences, Sendai, Japan

4 Department of Radiation Oncology, Tohoku University School of Medicine, 1-1 Seiryo-chou, Aoba-ku, Sendai 980-8574, Japan

For all author emails, please log on.

Radiation Oncology 2012, 7:182  doi:10.1186/1748-717X-7-182

Published: 31 October 2012

Abstract

Background

The purpose of this study is to investigate the prognostic factors of stereotactic radiotherapy for stage I NSCLC to improve outcomes.

Methods

Stage 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.

Results

Eighty 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%.

Conclusions

Our 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.

Keywords:
Stereotactic radiotherapy; SBRT; Non-small cell lung cancer; NSCLC; Prognostic factor; Minimum dose; PTV margin