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 progression-free 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 cm(3) for GTV(pre), 20 cm3 for GTV(post), and 50% for VRR. The smaller GTV(pre) and GTV(post) 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 GTV(pre) indicated significantly improved OS (p = 0.001), PFS (p = 0.013) and LRPFS (p = 0.002), while smaller GTV(post) 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, GTV(pre) was an independent prognostic factor of survival. Notably, improved outcome was not correlated with higher VRR after short-term follow-up with CT alone.