The effect of tumor volume and its change on survival in stage III non-small cell lung cancer treated with definitive concurrent chemoradiotherapy.

Background To investigate a prognostic role of gross tumor volume (GTV) changes on survival outcomes following concurrent chemoradiotherapy (CCRT) in stage III non-small-cell lung cancer (NSCLC) patients. Methods We enrolled 191 patients with stage III NSCLC from 2001 to 2009 undergoing definitive CCRT. The GTV of 157 patients was delineated at the planning CT prior to CCRT and with a follow-up CT 1 month after CCRT. We assessed the volumetric parameters of pre-treatment GTV (GTV_pre) post-treatment GTV (GTV_post), and volume reduction ratio of GTV (VRR). The primary endpoint was overall survival (OS) and secondary endpoints were progressionfree survival (PFS) and locoregional progression-free survival (LRPFS). The best cut-off value was defined as that which exhibited the maximum difference between the two groups. Results The median follow-up duration was 52.7 months in surviving patients. Median survival, 3- year OS, PFS and LRPFS rates were 25.5 months, 36.4%, 23.0%, and 45.0%, respectively. The selected cut-off values were 50 cm³ for GTVpre , 20 cm³ for GTVpost , and 50% for VRR. The smaller GTVpre and GTVpost values were associated with better OS (p < 0.001 and p = 0.015) and PFS (p = 0.001 and p = 0.004), respectively, upon univariate analysis. The higher VRR of > 50% was associated with a trend toward poorer OS (p = 0.004) and PFS (p = 0.054). Upon multivariate analysis, smaller GTVpre indicated significantly improved OS (p = 0.001), PFS (p = 0.013) and LRPFS (p = 0.002), while smaller GTVpost was marginally significant for PFS (p = 0.086). Higher VRR was associated with a trend toward poorer OS (p = 0.075). Conclusions In patients with stage III NSCLC undergoing definitive CCRT, GTVpre was an independent prognostic factor of survival. Notably, improved outcome was not correlated with higher VRR after short-term follow-up with CT alone. [ABSTRACT FROM AUTHOR]