BACKGROUND/AIMS: The aim of this study was to evaluate the influence of recent chemotherapy on the patterns of the maximum-standardized uptake value (M-SUV) and sensitivity of 18F-fluoro-deoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in colorectal cancer. METHODS: We retrospectively analyzed the FDG-PET/CT of 509 patients who underwent surgery for colorectal cancer. Subgroup analysis was performed according to chemotherapy status; 401 patients were not treated with chemotherapy and 108 patients were treated with chemotherapy within 6 months prior to surgery. Pathologic analysis of the surgical specimen was used as the gold standard. RESULTS: The M-SUV was significantly lower in patients treated with chemotherapy than in those not treated with chemotherapy in pathologically confirmed same stages of disease. The difference in the sensitivity of the M-SUV according to chemotherapy status was greatest using a cutoff M-SUV value of 6.4 (p<0.001). The longest diameter of the primary tumor was the most important factor that correlated with M-SUV of the primary tumor irrespective of the chemotherapy effect (p<0.001). The M-SUV of the primary tumor was not an independent predictor of lymph node metastasis in colorectal cancer. CONCLUSIONS: The results indicate that the M-SUV of FDG-PET/CT should be interpreted in the context of concurrent chemotherapy.
Aged ; Antineoplastic Agents/*adverse effects ; Chemoradiotherapy, Adjuvant/adverse effects ; Chemotherapy, Adjuvant/adverse effects ; Colorectal Neoplasms/drug therapy/pathology/*radionuclide imaging ; Female ; Fluorodeoxyglucose F18/diagnostic use/*pharmacology ; Humans ; Male ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Positron-Emission Tomography/methods ; Radiopharmaceuticals/diagnostic use/*pharmacology ; Retrospective Studies

The active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 (calcitriol), inhibits the growth of several types of human cancer cells in vitro, but its therapeutic use is limited because it causes hypercalcemia. Among its analogs, 19-nor-1,25-dihydroxyvitamin D2 (paricalcitol), has fewer calcemic effects and exhibits an activity equipotent to that of calcitriol. We assessed the antitumor and anti-inflammatory effects of paricalcitol in gastric cancer cells, and evaluated the potential role of vitamin D in the treatment of peritoneal metastatic gastric cancer. In this study, treatment with paricalcitol inhibited gastric cancer cell growth and induced cell cycle arrest. Paricalcitol also induced apoptosis and showed anti-inflammatory activity. Moreover, the growth of intraperitoneal metastases in vivo was reduced in mice treated with paricalcitol. 18F-FDG uptake was significantly lower in the paricalcitol group compared to control group (SUV; control group 13.2 +/- 5.3 vs paricalcitol group 4.5 +/- 3.0). Intraperitoneal tumor volume was significantly lower in paricalcitol treated mice (control group 353.2 +/- 22.9 mm3 vs paricalcitol group 252.0 +/- 8.4 mm3). These results suggest that the vitamin D analog, paricalcitol, has anticancer activity on gastric cancer cells by regulation of the cell cycle, apoptosis, and inflammation.
Animals ; Antineoplastic Agents/chemistry/*pharmacology/therapeutic use ; Apoptosis/drug effects ; Cell Cycle Checkpoints/drug effects ; Cell Cycle Proteins/metabolism ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Disease Models, Animal ; Ergocalciferols/chemistry/*pharmacology/therapeutic use ; Fluorodeoxyglucose F18/chemistry/diagnostic use ; Humans ; Mice ; Mice, Inbred BALB C ; Peritoneal Neoplasms/drug therapy/*secondary ; Positron-Emission Tomography ; Stomach Neoplasms/drug therapy/*pathology ; Transplantation, Heterologous