| Part I The predictive value of pretreatment18F-FDG PET-CT on overall survival of patients with inoperable esophageal squamous cell carcinomaPurpose To analysis metabolic parameters of pretreatment18F-FDG PET-CT and investigate the relationship between pretreatment PET-CT and overall survival of those patients with inoperable ESCC.Materials and Methods Patients of ESCC with a pretreatment PET-CT scan treated with chemoradiotherapy or radiotherapy in our center in recent years were included in this study. A threshold of SUV=2.5was used to establish the primary lesion in PET image. Metabolic factors including MTV, SUV and clinical factors like sex, age, stage, et al were calculated. The association of these factors and the results of long-term follow-up of the patients were examined. Overall survival was estimated were estimated using the Kaplan-Meier method. Significance between groups was assessed by Log-Rank test. Multivariate analysis was performed to identify the prognostic factors influencing OS using Cox proportional hazards regression model.Results Between2007.1and2010.8,30,30patients were enrolled in this study.Mean follow-up for all analyzable patients was19.5months, lyr-,2yr-,3yr-OS for the whole group was76.7%、52.1%、26.5%、 Univariate analysis showed patients having tumors with a length of primary lesion less than4cm (p=0.024) or MTV less than19.45cm3(p=0.006) had a better survival than those with a greater one, In the Cox multivariate analysis, MTV (p=0.012) were significant predictors of overall survival.We didn’t find a significant relationship between SUV and OS.Conclusion The present study shows that tumor volume parameters, especially MTV was valuable for predicting long-term survival. Part Ⅱ The predictive value of pretreatment18F-FDG PET-CT on local control of patients with inoperable esophageal squamous cell carcinomaPurpose The objective of this study is to evaluate the prognostic value of pretreatment18F-FDG PET/CT on local control after radical radiotherapy or chemoradiotherapy in patients with ESCC.Materials and Methods Patients with a pretreatment PET-CT scan treated with chemoradiotherapy or radiotherapy were included in this study. A threshold of SUV=2.5was used to establish the primary lesion in PET image. Metabolic factors including MTV, SUV and clinical factors like sex, age, stage, et al were calculated. The association of these factors and the results of long-term follow-up of the patients were examined. Local progression-free survival was estimated were estimated using the Kaplan-Meier method. Significance between groups was assessed by Log-Rank test. Multivariate analysis was performed to identify the prognostic factors influencing local control using Cox proportional hazards regression model.Results Between2007.1and2010.8,30,30patients were enrolled in this study.Mean follow-up for all analyzable patients was19.5months, lyr-,2yr-,3yr-local control rate for the whole group was72.0%、56.7%、56.7%. Univariate analysis showed patients having tumors with a SUVmax<12.6(p=0.032) or SUVmean<5.79(p=0.044) or MTV<19.45cm3(p=0.018) had a better local control than those with a greater one, In the Cox multivariate analysis, MTV (p=0.031) were significant predictors of local control.Conclusion The present study shows that tumor volume parameters, especially MTV was valuable for predicting local progression-free survival. Part Ⅲ The potential value of pretreatment18F-FDG PET-CT in in guiding individualized radiotherapy of patients with esophageal squamous cell carcinomaPurpose:The objective of this study is to evaluate the prognostic value of pretreatment18F-FDG PET/CT on local control (LC) after radical radiotherapy or chemoradiotherapy in patients with ESCC, and investigate its potential value in establishing optimal radiation treatment plans.Materials and methods:Thirty patients with pathologically proven ESCC who underwent pretreatment18F-FDG PET-CT in our cancer center were retrospectively reviewed. A threshold of SUV2.5was used to delineate the target volume of primary tumor separately. Coefficient of variation (COV) was used to evaluate the heterogeneity within the primary lesion. SUV and MTV of every pixel in all primary malignant lesions delineated on PET-CT images were measured. Cumulative SUV-volume histograms (CSH), describing total tumor volume above threshold of SUV (from2.5to SUVmax), were calculated. Receiver operating characteristics (ROC) curve was used to further evaluate the optimal cutoff for predicting local control. The local control was estimated using the Kaplan-Meier method and significance between groups was assessed by Log-Rank test.Results:COV of the group with a MTV<19.45cm3was0.35, smaller than that of the group with a MTV>19.45cm3(0.51, p=0.0001). ROC curve showed MTV=12.85cm3when delineated with a threshold of SUV=5might be the best cut off values. Local control for patients with MTVSUV≥5<12.85cm3on pretreatment18F-FDG PET-CT scan were better than those with higher MTVSuv≥5>12.85cm3(p=0.003).Conclusions:In this study, MTV above some threshold of SUV assessed by pretreatment PET/CT might be an adverse factor predicting local control in esophageal SCC, which indicated variation of biologically metabolic level within tumors should be consider as well as tumor volume promising for selecting risk-adapted therapies. These results will need to be validated in larger cohorts with longer follow-up, and evaluated prospectively. Part IV Spatial dynamic distribution and stability of F-FDG uptake locations within tumor during radiotherapy for esophageal squamous cell carcinomaPurpose:Because individual tumors are heterogeneous, including for18F-FDG uptake and, most likely, for radioresistance, selective boosting of high FDG uptake zones within the tumor has been suggested. To do this, it is critical to know whether the location of these high FDG uptake patterns within the tumor remain stable during radiotherapy (RT).Materials and methods:Seven patients with ESCC treated with concurrent chemo-radiation underwent repeated F-FDG PET-CT scans before RT and after20fractions of RT. On all scans, the high and low FDG uptake regions were autodelineated using several SUV thresholds, varying from40%to70%of SUVmax on the pretreatment scan (GTV4o%pre, GTV5o%Pre, GTV6o%Pre, GTV7o%Pre)and from70%to90%of SUVmax on the dur-treatment scan (GTV7o%dur, GTV8o%dur, GTV9o%dur) and fixed thresholds of2.5and5(GTV2.5pre, GTV5pre). The volumes and overlap fractions of these delineations were calculated to demonstrate the stability of the high FDG uptake regions during RT.Results:The high uptake regions within the tumor during RT largely corresponded (OF>70%) with the50%SUVmax high FDG uptake area (GTV50%pre,) of the pretreatment scan. The hotspot within the residual area (GTV9o%dur) was completely within the GTV and pre-radiotherapy high uptake regions (OF=100%). The volumes of the thresholds varied markedly. Although the location of the high FDG uptake patterns within the tumor during RT remained stable, the delineated volumes varied markedly.Conclusions:The location of the high FDG uptake areas within the tumor remained stable during RT. This knowledge may enable selective boosting of high FDG uptake areas within the tumor. |
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