Shrinkage Heterogeneity Between Primary Tumor And Regionally-metastasized Lymph Nodes In Locally Advanced Non-small Cell Lung Cancer Treated By Chemoradiotherapy

Objective:Image-guided individual treatment based on regional tumor control rate has been a research hotspot of locally-advanced NSCLC.Concurrent chemoradiotherapy has become standard treatment for locally advanced NSCLC.To investigate whether there was dissimilarity of volumetric shrinkage rate(VSR)between primary tumor and regionally-metastasized lymph nodes of locally advanced non-small cell lung cancer(NSCLC)treated by concurrent chemoradiotherapy and to explore the influential factors.Methods:A retrospective review identified patients diagnosed with locally advanced NSCLC of stage IIIA or IIIB in Shandong Cancer Hospital between July 1,2014 and December 31,2016.Thirty-two patients who both underwent baseline 18F-FDG PET-CT scan within 4 weeks before treatment and treated with concurrent chemoradiotherapy were enrolled.The target lesions were delineated on each patient's PET and CT images(enhanced planning CT and follow-up CT)respectively.Parameters such as metabolism parameters were automatically calculated and output as a table by MIM software.Volumetric shrinkage rate(VSR)and overall response rate(ORR)was calculated from gross tumor volume(GTV)delineated on CT scans.Relationship between VSR or ORR and metabolism parameters were analyzed.Results:1.The average VSR of primary tumor was significantly higher than the average VSR of regionally-metastasized lymph nodes(59.8%vs.34.14%,Z=-3.235,P =0.001).SUVmax-nd(maximum standard uptake value of regionally-involved lymph node,SUVmax-nd)was the only significant influential factor to VSR in multivariate analysis.2.ORR in primary tumor was 56.3%and in regionally-metastasized lymph nodes was 31.0%.ORR was much more significant in primary tumor(x2=6.326,P=0.012).Similarly,SUVmax was the only significant influential factor to primary tumor and regionally-involved lymph nodes multivariate analysis.3.Receiver operating characteristic curve(ROC)analysis showed SUVmax-nd=6.9 was an optimally predictive cut-off value of short-term efficacy in regionally-metastasized lymph nodes,but one was not found in primary tumor.The average VSR of regionally-involved lymph nodes with SUVmax-nd?6.9 was 57.23%(95%CI:45.47%-68.98%)versus those with SUVmax-nd<6.9 was 20.04%(95%CI:3.33%-36.74%).Two groups had statistical significance(Z=-3.438,P =0.001).ORR of regionally-involved lymph nodes with SUVmax-nd>6.9 was 51.5%versus those with SUVmax-nd<6.9 was 20.4%and they were statistically significant(x2 =9.103,P =0.003).Conclusions:In locally advanced NSCLC with concurrent chemoradiotherapy,VSR in primary tumor was more pronounced than regionally-involved lymph nodes and pretreatment SUVmax-nd may be a predictive variable.Similarly,SUVmax-nd was an effective prognostic factor for short-term-efficacy of regionally-involved lymph nodes treated with concurrent chemoradiotherapy.