Other modalities available for the palliation of esophageal carcinoma include lasers, photodynamic therapy, bipolar electrocoagulation therapy (BICAPTM), and local injection therapy, along with radiation therapy (including brachytherapy).
The neodymium/yttrium-aluminum-garnet laser (Nd/YAG) was introduced in 1982 . The laser, which operates at a wavelength of 1060nm, widens the lumen by locally heating and vaporizing the tumor. When feasible, the endoscope is passed through the tumor and the therapy performed during withdrawal. This allows better control and a lower perforation rate than can be obtained with antegrade therapy . Following laser therapy, the esophageal lumen is increased in diameter but may show residual tumor mass. In other cases, the mucosal surface may be irregular and thickened, resembling an esophagitis. In still others, the residual lumen is narrowed with smooth margins, appearing as a benign stricture, though this is less commonly encountered . Early complications include perforation, bleeding, and airway fistulization (Fig. 2.35). Complication rates range
Figure 2.35. Esophageal changes following laser therapy. Esophagogram demonstrates an irregular margin to the esophagus consistent with a carcinoma. An esophageal-bronchial fistula has developed secondary to recent laser therapy of the obstructing lesion. Note that there is no longer any significant esophageal obstruction.
as high as 20% for those treated with laser therapy . Both pneu-momediastinum and pneumoperitoneum have been reported post-therapy . Restenosis may occur over time.
Photodynamic therapy is based on the administration of a photosensitizing agent that is preferentially localized in neoplastic tissue. In Canada and Europe, 5-aminolevulenic acid is orally administered [122,125]. In the United States, porfirmen sodium is the only approved agent, and it is administered intravenously. On exposure to a properly tuned laser (wavelength of 630 nm) oxygen free radicals are formed [122,125]. These cause local cell death and subsequent tumor necrosis. The depth of affected tissue is less than that seen with conventional laser therapy, and therefore perforation is expected less often. Side effects include sunburn and are more commonly seen than in conventional laser treatments .
The BICAPTM technique is based on the direct application of heat generated by an electric current. An olive-shaped bipolar electrode is utilized, and no grounding plate is needed because the electrodes are situated close together on the probe. The electrocoagulation probe is placed distal to the malignant stricture following preliminary dilatation. An electric current, applied as the endoscope and electrode are withdrawn, circumferentially deposits the energy in the surrounding malignant tissue. This results in tissue desiccation during which the tissue resistance increases, thus limiting the depth of the destructive effect . Inflatable balloon probes have also been developed .
Local injection therapy, which acts via tissue necrosis and subsequent sloughing, has also been utilized in palliating malignant strictures . Substances injected have included dehydrated ethanol, sodium morrhuate, polidocanol, and chemotherapeutic agents . Carbon-adsorbed peplomycin, a bleomycin derivative, has also shown promising results [126,127].
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