Positron Emission Tomography derived Parameters as Predictive Factors andSurvival in Non-small Cell Lung Cancer Patients

Background: CT-PET (Computed Tomography-Positron Emission Tomography) provides additional information regarding tumour characteristics, aggressive tumour behaviour and serves as a prognostic indicator. Methods: Thirty one patients with NSCLC were retrospectively reviewed. PET parameters were calculated including maximum and mean Standardised Uptake Value (SUV), Metabolic Tumour Volume (MTV) and Total Lesion Glycolysis (TLG=MTV× SUVmean). The correlation between each parameter was investigated using Pearson's correlation tests. The tumour doubling time (DT) was calculated from pre-treatment and treatment planning CT scans. The DT was divided into 2 groups: A-rapid (DT 180 d) for survival calculation. Results: The mean age at diagnosis was 75 (55-87) years, 22 (66.7%) were male and 9 (27.3%) were female. The majority of patients had stage I and II (93.5%) disease. The correlation between DT to TLG and SUVmean was significant with Pearson's correlation of -0.363 (p-value of 0.045 on 2 tailed) and -0.399 (p-value of 0.024 on 2 tailed) respectively. DT correlation to SUVmax and MTV was not significant on Pearson’s correlation of -0.337 (p- value of 0.064 on 2 tailed test) and -0.309 (p-value of 0.091 on 2 tailed) respectively. The 2 year overall survival was 45.2% and median survival was 503 days for the whole group. The median survival was 468 days in group A-rapid and 503 days in B-slow group patients. There was no statistically significant difference between the groups (Log Rank Mantle Cox with p-value=0.681). Conclusions: This study compares the relationship of PET parameters (SUV, MTV and TLG) and DT and prediction of prognostication. Although the clinical significance can be far reaching at this stage, TLG and SUVmax are promising predictive factors for doubling time in NSCLC. Larger studies are needed to support the findings.