Correlation Of Lung Cancer Primary Tumor FDG Uptake With Lesion Size And Metastasis

Objective The present study observed the relationship between primary tumor FDG uptake and the presence of nodal or distant metastases at diagnosis in lung cancer patients and investigated its underling mechanism.Methods Newly diagnosed lung cancer patients who accepted ¹⁸F-FDG PET/CT staging in the nuclear medicine center of Shandong Cancer Hospital between December,2003 and October,2007 were retrospectively reviewed.Two hundred and forty three patients were included for analysis and none of the enrolled patients had received prior treatment.Tumor size was quantitated as the greatest dimension on CT images and FDG uptake as the maximum standardized uptake value(SUVmax). SUVmax of the primary lesions were analyzed by the different factors such as age, gender,histology type,lesion size and histology grade.All enrolled patients were divided into 3 groups by metastatic status:no metastasis,only lymph node metastasis and distant metastasis.The relationships among primary lesion SUVmax,its size and metastatic status were analyzed.The expressions of G1ut1,MMP2,CD44v6,EGFR and VEGF were detected immuno-histochemically in operated lung cancer patients. And correlation analyses were carried out between expression level of these factors and SUVmax obtained from preoperative FDG PET.Resultsâ‘ Primary tumor SUVmax demonstrates statistical significance difference by different histology type,histology grade and lesion size,but not by different gender or age interval,respectively.Squamous cell carcinomas and small cell carcinomas accumulate more FDG than adenocarcinomas(P=0.022).There is significant difference between low-moderate and high grade groups in SUVmax (P=0.008)and the SUVmax has a positive correlation with lesion size(P=0.000). Significant statistic differences were found between no metastasis group and lymph node or distant metastasis group(P =0.041,P=0.002,respectively).The odds of metastases increase significantly by 1.112 with each unit increase of SUVmax in the primary tumor(P=0.032).A moderate correlation was found in the expressions of G1ut1 and VEGF with SUVmax,respectively.And a low correlation was also found for MMP2,CD44v6 and EGFR with SUVmax,respectively.â‘¡Ninety-four Adenocarcinoma(AC)and 65 squamous cell carcinoma(SCC)patients were analyzed.Significant difference is found between different metastastic status groups for AC patients in SUVmax(P=0.000)and in size(P=0.035).Neither size nor SUVmax demonstrated significant difference between different metastatic status for SCC patients(P=0.874 and 0.749,respectively).Logistic regression analysis demonstrated that SUVmax was a significant factor of predicting the presence of nodal or distant metastases for AC patients(P=0.002),but not for SCC(P=0.608). A significant correlation was found between clinical stage and SUVmax for AC(r=0.420,P=0.000),but not for SCC(r=0.083,P=0.509).â‘¢One hundred and seven small(≤3.0cm)lung cancer patients were enrolled.The SUVmax demonstrated no statistic difference among different histology type groups.Significant statistic difference is found among different metastatic status groups in FDG uptake (P=0.001),but not lesion size(P =0.387).There was a statistically significant increase in the probability of metastases at presentation with each unit increase in SUVmax.(OR=1.469;P=0.001).Conclusionsâ‘ The lesion size,histology type and grade,but not age and gender,are factors influencing lung cancer primary tumor FDG uptake.Increased SUVmax in primary tumor evaluates the odds of nodal or distant metastases at presentation,which suggests that the FDG uptake value should be an indicator of metastases in lung cancer.And correlations were found between SUVmax and the immuno-histochemical expressions of some factors involved in metastasis.â‘¡Primary tumor SUVmax is predictive of the presence of nodal or distant metastases for AC,but not for SCC.And it demonstrates significant correlation between clinical stage and SUVmax for AC,but not for SCC.â‘¢In small lung cancer group,the SUVmax shows no statistic difference among different histology type.The SUVmax of primary lesion in metastatic cases is higher than no metastasis ones which suggest that the FDG uptake is a potential indicator of metastases in small lung cancer.