Esophagus - Cryotherapy Ablation of Early Esophageal Cancer
Comments: This video presentation will demonstrate the use of a new endoscopic ablation technology, endoscopic cryotherapy ablation, of an early esophageal cancer.
The patient is an 86 year-old man with newly diagnosed esophageal cancer. Endoscopy shows a 6 cm segment of Barrett’s esophagus, with a 4 cm area of depressed mucosa and a nodule in the distal esophagus.
Biopsy of the area of depressed mucosa demonstrated poorly differentiated adenocarcinoma.
Mucosal resection of the nodule also demonstrated poorly differentiated adenocarcinoma, incompletely resected.
Endoscopic ultrasound performed prior to biopsy showed wall thickening involving the mucosal and submucosal layers. No pathologically enlarged lymph nodes or evidence of metastasis were seen by EUS, CT or PET scan. The patient was not considered a candidate for esophagectomy due to age and co-morbid medical conditions, and he refused treatment with radiation or chemotherapy.
Endoscopic cryotherapy ablation is a visually directed, non-contact method of freezing mucosa using low pressure liquid nitrogen spray delivered via, a 7 french catheter inserted through the working channel of a standard endoscope. The patient was treated under and IRB-approved research protocol.
The area to be treated is examined endoscopically prior to treatment. The nodule, previously removed by mucosal resection, has not returned. Some healing is seen in the depressed mucosal area.
Liquid nitrogen expands approximately 700 times upon evaporation. To prevent excessive gaseous distension, a modified orogastric tube, or cryo- decompression Tube, is placed over a wire into the stomach prior to cryotherapy. The tube is withdrawn until the proximal side holes are adjacent to the targeted lesion.
The cryospray catheter is next passed through the endoscope and positioned with the catheter end just distal to the distal tip of the scope.
The catheter is positioned adjacent to the targeted lesion, then the spray is initiated by way of a foot pedal controlling the console. Until the catheter has cooled suffiiently (typically 10-12 seconds), no freezing of mucosa occurs.
As the catheter cools, liquid nitrogen exits the spray catheter tip and freezes the mucosa.
Once the initial tissue freezing occurs, the catheter is manipulated to freeze adjacent areas. The target area is frozen for 20 seconds. After 20 seconds, an alarm is sounded and the spray is stopped. Tissue is allowed to thaw.
After the mucosa is allowed to thaw for at least 45 seconds, liquid nitrogen is applied to the same area and kept frozen for another 20 seconds. Again, once freezing of the initial tissue is seen, the catheter is manipulated to freeze adjacent tissue. We see that the tissue freezes more quickly upon repeat applicaton.
The tissue also thaws more slowly with each successive freeze/thaw cycle. Each area is frozen and thawed for 3 cycles.
After the 3rd cycle, a new section of abnormal mucosa is chosen and the process is repeated, with 3 freeze/thaw cycles. Areas treated in the initial cryotherapy session include the distal 2-3 cm of the esophagus in the areas previously biopsy proven to be cancer.
Follow-up endoscopy is performed 6 weeks later. The abnormal mucosa has regressed significantly, with almost half of the tumor and Barrett’s mucosa replaced by squamous mucosa.
The first area of treatment is an area of persistent nodular mucosa
The cryospray is directed toward the nodular area. Once this tissue is frozen, the spray is directed toward adjacent areas.
The tissue is allowed to completely thaw before the liquid nitrogen spray is reapplied.
Re-freezing occurs more rapidly, and thawing more slowly, during the 2nd and 3rd freeze-thaw cycles.
Six weeks later, repeat endoscopy shows complete healing. A residual tongue of Barrett’s mucosa is seen on the left wall
A patch of reddened nodular mucosa is seen at the squamocolumnar junction.
An area of nodular mucosa on the anterior wall is also seen.
Treatment is first directed toward the reddened nodular mucosa at the gastroesophageal junction. This is partially obscured by the orogastric tube, however the spray is diverted around the tube to freeze the intended area.
Next, treatment is directed toward the nodular mucosa on the anterior wall.
Finally the residual tongue of Barrett’s mucosa on the left wall is treated.
6 weeks later, careful endoscopic evaluation shows no evidence of residual carcinoma or obvious Barrett’s mucosa. Tattoos indicate the site of tumor distally and margin of Barrett’s mucosa proximally.
Biopsies of the esophagus show normal squamous mucosa. Biopsies immediately below the gastroesophageal junction show intestinal metaplasia with focal low-grade dysplasia, but no evidence of carcinoma. The primary endpoint for this trial is ablation of carcinoma. The patient now enters the observation phase of the protocol, with periodic endoscopy with biopsy and CT/PET scanning.
| Contributed by: |
Bruce D. Greenwald, M.D. Associate Professor of Medicine University of Maryland School of Medicine |
|
Citation: Greenwald, BD (May 21 2007). Esophagus - Cryotherapy Ablation of Early Esophageal Cancer. The DAVE Project. Retrieved Jul, 30, 2010, from http://daveproject.org/viewfilms.cfm?film_id=604 Times viewed since Feb 2006: 13646 |
|
