Prospective Study of Chromogranin A as a Predictor of Progression in Patients with Pancreatic, Small-Intestinal, and Unknown Primary Neuroendocrine Tumors.

BACKGROUND: Retrospective studies are conflicting but most of them report that an increase in plasma chromogranin A (CgA) predicts tumor progression in neuroendocrine tumor (NET) patients. Prospectively, we investigated if a change in plasma CgA is associated with tumor burden changes in NET patients with disseminated disease. METHODS: We included 239 patients treated at 5 NET centers from December 2010 to December 2013. CgA was measured within 6 weeks of a CT or MRI in a patient undergoing at least 2 scan examinations performed over a period of 1-24 months. In a post hoc analysis, CgA measured 3-6 months prior to the CT/MRI was analyzed. Changes in tumor size were evaluated by RECIST1.1. A 25% change in CgA was chosen to discriminate between increased, decreased, or unchanged levels. RESULTS: In 671 events (2 CT/MRI scans and 2 corresponding CgA measurements), we found a weak positive correlation between the RECIST 1.1 responses and change in plasma CgA from baseline (Spearman's rank correlation coefficient: 0.15; p < 0.05). Of 304 events in the post hoc analysis, 58 showed progression, 228 showed stable disease, and 18 showed regression, with a median change in CgA of 19% (IQR: 57 to -20%), -12% (23 to -38%), and -73% (-55 to -83%), respectively. The correlation coefficient for all sites was 0.17 (p = 0.003), and it was 0.16 (p = 0.07), 0.18 (p = 0.04), and 0.20 (p = 0.21) for small-intestinal (n = 137), pancreatic (n = 123), and unknown primary NET (n = 40), respectively. In the 58 patients showing tumor progression, the sensitivity and specificity of an increased CgA concentration were 36 and 82%, respectively, with positive and negative predictive values of 32 and 85%. CONCLUSIONS: In this prospective study of gastroenteropancreatic NET patients, we observed only a weak association between a change in plasma CgA and changes in tumor burden. CgA as a single biomarker was thus inadequate to predict tumor progression.

Impact of spectral body imaging in patients suspected for occult cancer: a prospective study of 503 patients.

OBJECTIVES: To investigate the diagnostic impact and performance of spectral dual-layer detector CT in the detection and characterization of cancer compared to conventional CE-CT. METHODS: In a national workup program for occult cancer, 503 patients (286 females and 217 males) were prospectively enrolled for a contrast-enhanced spectral CT scan. The readings were performed with and without spectral data available. A minimum of 3 months between interpretations was implemented to minimize recall bias. The sequence of reads for the individual patient was randomized. Readers were blinded for patient identifiers and clinical outcome. Two radiologists with 9 and 33 years of experience performed the readings in consensus. If disagreement, a third radiologist with 11 years of experience determined the outcome of the reading RESULTS: Significantly more cancer findings were identified on the spectral reading. In 73 cases of proven cancer, we found a sensitivity of 89% vs 77% and a specificity of 77% vs 83% on spectral CT compared to conventional CT. A slight increase in reading time in spectral images of 82 s was found (382 vs 300, p < 0.001). For all cystic lesions, the perceived diagnostic certainty increased from 30% being completely certain to 96% most pronounced in the kidney, liver, thyroid, and ovaries. And adding the spectral information to the reading gave a decrease in follow-up examination for diagnostic certainty (0.25 vs 0.81 per reading, p < 0.001). CONCLUSION: The use of contrast-enhanced spectral CT increases the confidence of the radiologists in correct characterization of various lesions and minimizes the need for supplementary examinations. KEY POINTS: • Spectral CT is associated with a higher sensitivity, but a slightly lower specificity compared to conventional CT. • Spectral CT increases the confidence of the radiologists. • The need for supplementary examinations is decreased, with only a slight increase in reading times.

Economic impact of spectral body imaging in diagnosis of patients suspected for occult cancer.

BACKGROUND: Based on prior studies spectral CT has shown a higher sensitivity for malignant lesions than conventional CT at the cost of lower specificity. For the radiologists, it also offers a higher degree of certainty in the diagnosis of benign lesions. The objective of this study was to evaluate the economic impact of spectral CT in patients suspected of occult cancer in a medical center in Denmark. METHODS: This study was a secondary analysis using de-identified data from a prospective study of patients receiving a contrast-enhanced spectral CT scan. Based on suggested follow-up examinations on both spectral CT and contrast-enhanced CT, costs from a payer's perspective were determined using unit costs obtained from national databases. RESULTS: The dataset contained 400 patients. Overall, 203 follow-up procedures were eliminated based on spectral data reading. The largest reduction in suggested follow-up procedures was found for the kidney (83%), followed by the liver (66%), adrenal glands (60%), and pancreas (42%). The total estimated costs for suggested follow-up procedures based on spectral data reading were €155,219, 25.2% (€52,384) less than that of conventional CT reading. CONCLUSION: Our results provide support for spectral body imaging as an advanced imaging modality for suspected occult cancer. A substantial number of follow-up diagnostic procedures could be eliminated based on spectral data reading, which would result in significant cost savings.