Abstract
We tested the prognostic relevance of metabolic parameters and their relative changes in patients with metastatic colorectal cancer (mCRC) treated with monoclonal antibody and chemotherapy. SUVmax (standardized uptake volume), SAM (standardized added metabolic activity) and TLG (total lesion glycolysis) are assessed with 18F-fluorodeoxyglucosepositron emission tomography and computed tomography (FDG-PET/CT) to evaluate total metabolic activity of malignant processes. Our purpose was to investigate the change of glucose metabolism in relation to PFS (progression free survival) and OS (overall survival). Fifty-three patients with mCRC with at least one measurable liver metastasis were included in this prospective, multi-center, early exploratory study. All patients were treated with first-line chemotherapy and targeted therapy. Metabolic parameters, like SUVmax, SAM, normalized SAM (NSAM) and TLG were assessed by FDG-PET/CT, carried out at baseline (scan-1) and after two therapeutic cycle (scan-2). Our results suggested neither SUVmax nor TLG have such prognostic value as NSAM in liver metastases of colorectal cancer. The parameters after the two cycles of chemotherapy proved to be better predictors of the clinical outcome. NSAM after two cycles of treatment has a statistically significant predictive value on OS, while SAM was predictive to the PFS. The follow up normalized SAM after 2 cycles of first line oncotherapy was demonstrated to be useful as prognostic biomarkers for OS in metastatic colorectal cancer. We should introduce this measurement in metastatic colorectal cancer if there is at least one metastasis in the liver.
Highlights
Colorectal cancer (CRC) is the third leading cause of cancer-related death
That the metabolic changes induced by chemotherapy in tumor cells are predictive of patient outcome and that PET/computed tomography (CT) is more suitable for monitoring the response to therapy [4, 5] than other imaging modalities in targeted therapy in cancer
Current treatment standards of metastatic colorectal cancer (mCRC) are based on chemotherapy combined with monoclonal antibody Typically, therapeutic response is assessed by CT after three to four cycles of therapy, but an earlier prediction of clinical outcome would be desirable, to guide further treatment regimens
Summary
Colorectal cancer (CRC) is the third leading cause of cancer-related death. Colon cancer accounts for two thirds of all CRC cases and differs from rectal cancer in gender distribution and sites of metastases. PET/CT was suggested for patients with a high risk for extrahepatic metastases, as this method is expected to have higher sensitivity compared to CT. It is already obvious, that the metabolic changes induced by chemotherapy in tumor cells are predictive of patient outcome and that PET/CT is more suitable for monitoring the response to therapy [4, 5] than other imaging modalities in targeted therapy in cancer. Considering the lack of consensus on the use of the metabolic data based on PET/CT examinations, the aim of this prospective study was to compare the available metabolic parameters and to establish the prognostic value of baseline and follow-up PET/CT for the long-term outcome in patients with mCRC
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