Tumor ingrowth

The Gianturco stent is seldom used in the treatment of mahgnant biliary strictures because of the high rates of tumor ingrowth through the wide mesh. 

Cremer M, Deviere J, Sugai B et al (1990) Expandable biliary metal stents for malignancies endoscopic insertion and diathermic cleaning for tumor ingrowth. Gastrointest Endosc 36 451-457... 

Ell C, Fleig WE, Hochberger J (1992) Broken biliary metal stent after repeated electrocoagulation for tumor ingrowth. Gas-trointest Endosc 38 197 199... 

The major complications of metallic stenting include hemorrhage, migration, tumor ingrowth, tumor overgrowth, severe pain, perforation, and fistula formation (Saxon et al. 1994). 

Recurrent dysphagia occurs in 10%-36% of patients and maybe due to stent migration, food bolus obstruction, or recurrent strictures due to tumor ingrowth, tumor overgrowth (Acunas et al. 1996 Cwikiel et al. 1998 Song et al. 1994 Laasch et al. 1998 Saxon et aL 1995 Morgan et al. 1996 Bartelsmann et al. 2000). 

The ideal stent would be resistant to tumor ingrowth and migration. Researchers have been trying for some years to produce an uncovered stent with a coating material on the metallic mesh that would resist tumor ingrowth. Such a stent would have the optimal properties of covered stents (i.e., no tumor ingrowth) and uncovered stents (i.e., no migration). 

In the Japanese multicenter trial of the uncovered Ultraflex stent (Miyazawa et al. 2000), tumor ingrowth (24%) and tumor overgrowth (21%) were the most frequent complications during the 2-month follow up period. Mucus retention was noted in 9% and granuloma formation was seen in 3%. No migrations of the uncovered stents occurred. 

In the series of Strecker stent placement in 21 patients, complications were reported in two. One stent compression and one stent dislocation occurred in two patients. Both stents were removed without problems (WiTT et al. 1997). In a smaller trial, one Strecker stent out of five dislocated 6 days after placement (ScHMiDT et al. 1999). In the series of Hauck et al. (1997), tumor ingrowth through the stent was seen in nine of 51 patients treated with Strecker or nitinol stents. Stent deformation occurred only with Strecker stents ( =12), but not in nitinol stents. Mucus retention was a frequent problem within the first 7 days after stent placement (39%). 

However, the ideal stent has not yet been developed. Such a stent would combine ease of insertion, potential removal, resistance to migration and tumor ingrowth, no or minimal induction of granulation tissue formation, and preservation of mucociliary function. 

For palliation of dysphagia in patients with advanced EAC, laser and argon beam are the first choice for friable intraluminal disease (with stent use in the majority of cases). Covered stents should be used to minimize ingrowth of tumor. Covered stents are also the treatment of choice for perforated cancers and malignant tracheo-esophageal cancer. Chemotherapy should only be used in the context of appropriate controlled clinical trials. 

As uncovered stents are prone to ingrowth of tumor, covered endoprostheses should be used whenever possible. The choice of stent depends to some extent... 

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