The Impact of Primary Tumor and Locoregional Metastatic Lymph Node SUV on Predicting Survival in Patients with Rectal Cancer.

Objectives: The aim of this study was to evaluate the impact of maximum standard uptake value (SUV) of the primary tumor and locoregional metastatic lymph node in predicting survival in patients with the preoperative rectal adenocarcinoma.

Methods: One hundred and fifteen patients [mean age ± standard deviation (SD): 58.7±11.4 years] with biopsy-proven rectal adenocarcinoma underwent F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging for the staging were included in this study. All patients were followed-up for a minimum of 12 months (mean ± SD: 29.7±13.5 months). Tumor-node-metastasis 2017 clinical staging, SUV of the primary rectal tumor and locoregional lymph nodes on the PET/CT studies were evaluated.

Results: All patients had increased FDG activity of the primary tumor. The mean ± SD SUV of the primary tumor and locoregional metastatic lymph node were 21.0±9.1 and 4.6±2.8, respectively. Primary tumor SUV did not have an effect on predicting survival (p=0.525) however locoregional metastatic lymph node SUV had an effect (p<0.05) on predicting survival. Clinical stage of the disease was a factor predicting survival (p<0.001).

Conclusion: F-FDG PET/CT is an effective imaging modality for detecting primary tumors and metastases in rectal adenocarcinoma and clinical stage assessment with PET/CT had an effect on predicting survival. Furthermore, in our study locoregional lymph node SUV was defined as a factor in predicting survival.