Tumors and new endoscopic ultrasound-guided therapies

Abstract

With the advent of linear echoendoscopes, endoscopic ultrasound (EUS) has become more operative and a new field of oncological application has been opened up. From tumor staging to tissue acquisition under EUS-guided fine-needle aspiration, new operative procedures have been developed on the principle of the EUS-guided puncture. A hybrid probe combining radiofrequency with cryotechnology is now available, to be passed through the operative channel of the echoendoscope into the tumor to create an area of ablation. EUS-guided fine-needle injection is emerging as a method to deliver anti-tumoral agents inside the tumor. Ethanol lavage, with or without paclitaxel, has been proposed for the treatment of cystic tumors in non-resectable cases and complete resolution has been recorded in up to 70%-80%. Many other chemical or biological agents have been investigated for the treatment of pancreatic adenocarcinoma: activated allogenic lymphocyte culture (Cytoimplant), a replication-deficient adenovirus vector carrying the tumor necrosis factor-α gene, or an oncolytic attenuated adenovirus (ONYX-015). The potential advantage of treatment under EUS control is the real-time imaging guidance into a deep target like the pancreas which is extremely difficult to reach by a percutaneous approach. To date there are no randomized controlled trials to confirm the real clinical benefits of these treatments compared to standard therapy so it seems wise to reserve them only for experimental protocols approved by ethics committees.

Keywords: Alcohol injection; Anti-tumoral injection; Endoscopic ultrasound; Endoscopic ultrasound guided ablation; Pancreatic cancer.

Figure 1

The tip of the ERBE hybrid cryotherm probe with the active electrical part.

Figure 2

The ERBE flexible probe used for endoscopic ultrasound-guided ablation of the parenchymal organs. The probe, covered with a protection tube, is passed through the operative channel of the echoendoscope.

Figure 3

The cryotherm probe applied in the porcine pancreas: the probe is seen as an hyperechoic line. Initially an hyperechoic elliptic area appears around the distal tip of the probe, surrounded by a hypoechoic border (most likely edema).

Figure 4

Histopathologic section from the first pig: Normal pancreatic tissue (A) surrounds the central treated area (B).

Figure 5

Endoscopic ultrasound-guided puncture of a cystic tumor. The cyst is punctured with a 22-G fine needle under endoscopic ultrasound guidance, the fluid is aspirated, then ethanol is injected into the cyst and re-aspirated after 3-5 min.