Novel design fine-needle biopsy needles are ready to take over the supremacy of fine-needle aspiration needles for sampling of solid pancreatic masses

Endoscopic ultrasound (EUS)-guided tissue acquisition is a well-established method for pathological diagnosis of solid tumors wherever the needle can reach. However, there is currently conflicting evidence on whether any specific needle or technique is superior to others.

The use of EUS-guided fine-needle biopsy (FNB) needles has generated great interest, based on theoretical advantages over EUS fine-needle aspiration (FNA) needles in improving diagnostic accuracy (if we assume that a bigger sample is better, which is not always true), procurement of samples with preserved tissue (as cytology does not inform on the architecture of the lesion), and allowing immunohistochemistry or special stains required for certain diagnoses.

“...the results of this study support the use of EUS-FNB with a fork-tip needle over EUS-FNA in solid pancreatic masses.”

Attempts to obtain core tissue samples by EUS require cutting mechanisms. The first device was a trucut needle that had a high number of technical failures and was soon taken off the market. The reverse bevel needle was the first core biopsy needle widely used but, after initial promising results, it did not show unequivocal superiority over FNA. Over the past few years, new core biopsy needles have been manufactured with the aim of assessing an adequate tissue sample while avoiding the technical difficulties that usually appear when sampling the head of the pancreas from the duodenum. One such needle is the fork-tip, opposing bevel design, equipped with six cutting surfaces in an asymmetrical design. This is the EUS-FNB needle used in the study performed by Oppong et al. published in the current issue of Endoscopy [1]. The other is the Franseen design needle that has a three-plane symmetrical cutting surface. Both needles have been designed to maximize tissue capture and minimize fragmentation in order to acquire architecturally intact tissue.

Many articles with various methodological designs attempting to assess the performance of different needles in solid pancreatic masses have been published in recent years. Technical tips for tissue acquisition and the impact of on-site evaluation of the sample have been repeatedly tested as well. Moreover, several randomized controlled trials (RCTs) have compared EUS-FNA and EUS-FNB in this setting but reached inconsistent results. Five meta-analyses on the subject were also published within the past 4 years. Among the meta-analyses published to date, most of them [2–4] did not find significant differences between the two methods of tissue sampling in terms of diagnostic accuracy, which is in concordance with the most recent update of European guidelines that recommend FNA and FNB equally for routine sampling of solid masses [5]. However, in most of the mentioned meta-analyses there was a trend toward higher diagnostic accuracy and better specimen adequacy with EUS-FNB. The lower number of passes needed with EUS-FNB was a common finding in all of them. In contrast with these results, one meta-analysis [6] demonstrated superiority of EUS-FNB over EUS-FNA. Moreover, a very recent network meta-analysis [7] found that EUS-FNA and EUS-FNB were similar (with low confidence in estimates) in terms of diagnostic accuracy, sample adequacy, and histologic core procurement, independently of the gauge of needle used (19, 22 or 25 gauge). However, new meta-analyses using the network methodology are needed to confirm the results.

In this issue of Endoscopy, Oppong et al. present a randomized crossover study aimed at comparing fork-tip needle biopsy and FNA when sampling solid pancreatic masses with EUS [1]. In summary, the authors included 108 patients and found that the odds of diagnosing malignancy and the accuracy for a specific diagnosis with EUS-FNB were higher than that of EUS-FNA (3 and 4 times, respectively). Moreover, sampling and pathology viewing times were significantly shorter with EUS-FNB compared with EUS-FNA. Ease-of-diagnosis was also greater with FNB and the cost was comparable between the two types of EUS-guided tissue acquisition. Therefore, the results of this study support the use of EUS-guided fork-tip needle biopsy over EUS-FNA in solid pancreatic masses.

A relevant issue in EUS-FNA is the need for on-site evaluation of the sample, as published data demonstrate that it results in significantly fewer repeat EUS-FNA sessions to reach a diagnosis [8]. In contrast, some data suggest that the use of EUS-FNB with acquisition of adequate core tissue may avoid the need for on-site evaluation of the sample [9]. This might represent a substantial improvement in centers where the availability of a pathologist or expert cytotechnician is lacking. In the study by Oppong et al., there was no on-site evaluation of the sample obtained by EUS-FNA. Thus, it might be argued that, had a cytotechnician been available, the results may have been different, at least regarding the sampling and pathologist evaluation times.

Finally, although molecular testing may be done from a cellular block, mainly if an extra FNA pass is performed, a histological sample is always better. In the era of personalized medicine, the possibility of obtaining tissue from the tumor will be progressively more necessary to improve patient outcomes. EUS-guided tissue acquisition has become crucial in the diagnosis of solid pancreatic neoplasms because of its ability to perform safe sampling of the pancreas, although it has not impacted medical therapy to date. Hopefully, a deeper knowledge of the molecular pathways for pancreatic cancer development will lead to the improvement of targeted therapies in the near future, extending the role of EUS-guided tissue acquisition from an exclusively diagnostic tool to both diagnostic and therapeutic use. The improvement in the EUS-FNB needles, together with the performance of well-designed comparative studies to optimize needle design for specific lesions, is the next step to an encouraging future in the management of pancreatic cancer.

Publication History

Article published online:
27 May 2020

• References

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