Pancreatic cancer screening employing noncontrast magnetic resonance imaging combined with ultrasonography

Comparison between B-mode ultrasonography and contrast-enhanced ultrasonography for the surveillance of early stage pancreatic cancer: a retrospective study

Background

Contrast-enhanced ultrasonography (CE-US) brings a higher signal-to-noise ratio and a higher sensitivity for slow flow than traditional B-mode ultrasonography (US). However, it remains unclear whether CE-US is also superior to B-mode US in detecting early-stage pancreatic cancer (PC).

Methods

This was a retrospective study enrolling patients suspected of pancreatic insufficiency between June 2015 and December 2019. Enrolled patients successively received B-mode US and CE-US examinations, and some their demographic and clinical data were collected. The diagnostic capacity of the two examinations was calculated and receiver operating characteristic (ROC) curves was used to compare the area under the curve (AUC). A subgroup analysis was performed to explore the effects of tumor size on the diagnostic accuracy of B-mode US and CE-US.

Results

There were 128 patients enrolled in this study; 74 patients were diagnosed as early-stage PC patients and the remaining 54 were diagnosed with benign pancreatic lesions. The mean size of the PC was 17.8±4.9 mm. The results revealed that 68 of the 74 PC patients were correctly diagnosed by CE-US, and all 54 patients with benign pancreatic lesions were also correctly diagnosed. Meanwhile, only 55 of the 74 PC patients and 50 of the 54 patients with benign pancreatic lesions were diagnosed correctly using B-mode US. The ROC curve showed that the AUCs of CE-US and B-mode US were 0.959 and 0.835, respectively. According to the subgroup analysis, CE-US exhibited better accuracy than B-mode US for smaller tumors (size <20 mm, P=0.002; size <10 mm, P=0.043; size <5 mm, P=0.025).

Conclusions

CE-US was clearly superior to the conventional B-mode US in detecting early-stage PC, especially smaller sized PC.

Pancreatic cancer screening: Still a delusion?

Pancreatic adenocarcinoma represents the fourth most common cause of cancer mortality and death due to pancreatic cancer (PC) have increased since 2003. Its incidence has also raised about 30% in the past decade and it is expected to become the second cause of cancer mortality by 2020 in the USA. Most PC present with metastatic disease and improvements in treatment outcomes for this group have been disappointing. These observations support the idea that screening to identify patients at an earlier stage might be an important strategy in improving overall PC outcomes. Many protocols have been tested, nevertheless, by now there is no effective screening program. Given the overall low incidence of disease and the current lack of accurate, inexpensive and noninvasive screening tests, the consensus is that widespread population-based screening for PC in the general population or in patients with only one affected first-degree relative is neither practicable nor indicated in most countries. However, a different scenario is screening patients with higher risk for PC, most of them with hereditary conditions predisposing the development of this neoplasia. In fact, some guidelines are now available helping to select these individuals at risk and to screen them, in order to achieve early detection of PC.

Noninvasive characterization of pancreatic tumor mouse models using magnetic resonance imaging

The preclinical models of pancreatic adenocarcinoma provide an alternative means for determining the mechanisms of malignancy and possibilities for treatments, thus representing a resource of immense potential for cancer treatment in medicine. To evaluate different tumor models, quantifiable magnetic resonance imaging (MRI) techniques can play a significant role in identifying valuable in vivo biomarkers of tumor characteristics. We characterized three models of pancreatic cancer with multiparametric MRI techniques. Tumor stromal density of each tumor was measured using diffusion-weighted imaging and magnetization transfer (MT-MRI). Histologic measurement showed a similar trend with tumor fibrosis levels. Results indicated that MRI measurements can serve as a valuable tool in identifying and evaluating tumor characteristics.

Clinical importance of Familial Pancreatic Cancer Registry in Japan: a report from kick-off meeting at International Symposium on Pancreas Cancer 2012

Pancreatic cancer is still a highly lethal disease with a 5-year survival rate of approximately 5 %. Early detection offers one of the best hopes for improving survival. Previous cohort studies and case-control studies showed that 4-10 % of pancreatic cancers have a hereditary basis, and individuals with a family history have an increased risk of developing pancreatic and extra-pancreatic malignancies. Since individuals with a family history of pancreatic cancer and those with a known genetic syndrome that predisposes to pancreatic cancer will be the first to benefit from early detection tests as they become available, familial pancreatic cancer (FPC) registries have been established in the US and Europe, but not yet in Japan. Such registries form the basis for epidemiological studies, clinical trials, and basic research on familial pancreatic cancer. There is a need for FPC registries in Japan as cancer risk varies among different populations and discoveries made in Western populations may not translate to the Japanese population. These registries in Japan will align with ongoing international efforts and add to a better understanding of the natural history, risk factors, screening strategies, and responsible genes, for improving survival of this dismal disease.

Pancreatic cancer screening

Accumulating data indicate that clinically available abdominal imaging tests such as EUS and MRI/MRCP can detect asymptomatic precursor benign (IPMN, PanIN) and invasive malignant pancreatic neoplasms, such as ductal adenocarcinoma, in individuals with an inherited predisposition. These asymptomatic FPCs detected have been more likely to be resectable, compared to symptomatic tumors. The most challenging part of screening high-risk individuals is the selection of individuals with high-grade precursor neoplasms for preventive treatment (ie, surgical resection before development of invasive cancer). Ongoing and future research should focus on formulating and validating a model for FPC risk and neoplastic progression using patient characteristics, imaging, and biomarkers. The comparative cost and effectiveness of various approaches for screening and surveillance of high-risk individuals also deserves study. For now, screening is best performed in high-risk individuals within the research protocols in academic centers with multidisciplinary teams with expertise in genetics, gastroenterology, radiology, surgery, and pathology.

Magnetization transfer MRI in pancreatic cancer xenograft models

Magnetization transfer magnetic resonance imaging measurements were performed in three pancreatic ductal adenocarcinoma mouse xenograft models. For each of 28 pancreatic ductal adenocarcinoma xenografts, MT ratios (MTRs) were calculated and compared to histologic fibrosis levels from reference standard trichrome staining. MTR was found to be significantly higher in tumors grown using BxPC-3 cell line (39.4±5.1, mean±SD) compared to the MTR for the tumors grown from Panc-1 (32.4±2.8) and Capan-1 (27.3±2.9) cell lines (P<0.05 for each comparison). Histologic measurements showed a similar trend with BxPC-3 tumors demonstrating significantly higher fibrosis levels (percentage of fibrotic tissue area, 6.48±2.59) when compared to Panc-1 (3.54±2.18) and Capan-1 (2.07±1.60) tumors. MTR measurements were well correlated to quantitative fibrosis levels (r=0.69, P=0.01). Results indicated that MTR measurements offer the potential to serve as a valuable in vivo biomarker of desmoplasia in pancreatic ductal adenocarcinoma.