Local application of hyperthermia in the esophagus with a heatable malleable thermoplastic stent

This study measures the effect of hyperthermia applied through a heatable stent in the esophagus in order to investigate whether this procedure offers a therapeutic option for tumor treatment.

Thermoplastic malleable stents, with the capacity to be heated after implantation, were placed endoscopically in the middle third of the esophagi of 30 pigs. After placement the stents were heated in vivo for 60 min at temperatures ranging from 43 to 52 degrees C. Temperature was measured in the surrounding tissue at various distances from the stent, determining heat penetration. The esophagi were histologically examined after 7 days.

The maximal heating temperature tolerated in the esophagi without transmural necrosis was 46.5 degrees C, when applied twice for 60 min with a pause of 48 h. With this procedure a tumor damaging temperature of 42.5 degrees C was achieved at a maximum distance of 12 mm surrounding the stent.

Application of hyperthermia through a heatable stent in the esophagus is feasible. The maximal depth of therapeutic temperature achieved by this procedure (12 mm) is not sufficient to heal esophageal cancer, but may be of palliative value.