Novel Marker Guides Radiotherapy in Esophagogastric Cancer

Roxanne Nelson, RN, BN

August 06, 2015

A novel endoscopically inserted marker might help improve the radiologic assessment of esophagogastric cancers and allow for image-guided radiotherapy (IGRT), according to a small phase 2 pilot study.

Ten patients underwent IGRT with endoscopically inserted markers, which "resulted in significant improvement in radiological localization of the primary malignancy in the majority of our cohort and allowed for IGRT," write Sujievvan Chandran, MBBS, FRACP, from the Department of Gastroenterology at Austin Health in Melbourne, Australia, and colleagues.

The study was published online July 31 in Gastrointestinal Endoscopy.

Radiotherapy has become an accepted treatment for esophageal cancers and is currently being evaluated in conjunction with chemotherapy for the neoadjuvant treatment of gastric cancers, the researchers explain.

However, a limitation of delivering radiotherapy to patients with upper gastrointestinal (GI) malignancies is related to the mobility of the esophagus and stomach, "which results in the requirement of large target volumes with generous margins to account for this," they note.

The endoscopic ultrasound (EUS)-guided placement of gold coil fiducials has been investigated in gastric cancers. Fiducials are small gold markers that help target the radiation therapy to where it is most needed while sparing surrounding tissue. Their use with IGRT has been well established in breast and prostate cancer, and there is emerging literature on their role in GI cancers. However, there are substantial limitations to their widespread use, the researchers point out, including cost and EUS accessibility.

Dr. Chandran and his team looked for an alternative marking method to address the limitations of EUS-guided fiducials, and selected lipiodol in combination with n-butyl 2-cyanoacrylate, "given our experience with it in the management of gastric varices."

In addition, they point out, lipiodol alone with IGRT has been studied in the setting of bladder cancer and, more recently, in lung cancer, and has been shown to be a useful radiopaque marker.

Successful Placement and Treatment

In the pilot study, 13 (50.0%) patients had esophageal cancer, eight (30.8%) had esophagogastric junction cancer, and five (19.2%) had gastric cancer. A total of 92 novel radiopaque markers were placed in the 26 patients.

The main outcome measure was the successful insertion of the marker, based on radiologic, endoscopic, and histologic assessment.

Follow-up imaging assessed the markers inserted in 22 (88.0%) patients, and CT and/or PET–CT confirmed the placement of 79 of the 81 markers (97.5%) in this group.

In the subgroup of 10 patients (38.5%) who underwent IGRT with endoscopically inserted markers, seven had an esophageal cancer.

One patient in this subgroup died during the study from disease progression, two were disease-free 9 months after treatment, four experienced disease progression, and three are awaiting follow-up imaging to assess treatment response.

The longest follow-up was 24 months, but no early, late, or delayed adverse events from marker placement were reported.

The limitations of this pilot study relate primarily to the small cohort and the fact that it is from a single center. "However, despite this, our results have indicated that this technique is feasible and safe and allows IGRT as seen in 38.5% of our cohort," the researchers write.

"Although we have demonstrated promising results, a larger prospective multicenter study is required to validate these findings, which we are set to commence," they conclude.

The authors have disclosed no relevant financial relationships.

Gastrointest Endosc. Published online July 31, 2015. Abstract

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