Airway Complications After Covered Stent Placement ...

Va s c u l a r a n d I n t e r ve n t i o n a l R a d i o l o g y • O r i g i n a l R e s e a r c h Park et al. Complications of Stent for Esophageal Stricture

Downloaded from www.ajronline.org by University of Ulsan College of Medicine on 06/18/14 from IP address 210.122.170.6. Copyright ARRS. For personal use only; all rights reserved

Vascular and Interventional Radiology Original Research

Airway Complications After Covered Stent Placement for Malignant Esophageal Stricture: Special Reference to Radiation Therapy Ji Yeon Park1 Ji Hoon Shin2 Ho-Young Song2 Seong Yoon Yi 3 Jin Hyoung Kim 2 Park JY, Shin JH, Song HY, Yi SY, Kim JH

Keywords: airway complications, covered stent placement, malignant esophageal strictures, radiation therapy DOI:10.2214/AJR.10.5780 Received September 13, 2010; accepted after revision July 1, 2011. Supported by a grant from the Korea Health 21 R&D Project, Ministry of Health and Welfare, Republic of Korea (A060603), and a National Research Foundation of Korea Grant from the Korean Government (KRF-2005-206-E00015). 1

Department of Radiology, Kwandong University College of Medicine, Myongji Hospital, Goyang-si, Gyeonggi-do, South Korea. 2

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 86 Asanbyeongwon-Gil, Songpa-Gu, Seoul 138-736, Korea. Address correspondence to J. H. Shin ([email protected]).

3 Division of Hematology-Oncology, Department of Medicine, Inje University Ilsan Paik Hospital, Goyang-si, Gyeonggi-do, South Korea.

AJR 2012; 198:453–459 0361–803X/12/1982–453 © American Roentgen Ray Society

OBJECTIVE. The purpose of this study was to evaluate the characteristics of airway complications and survival with special reference to radiation therapy in the care of patients undergoing covered stent placement for malignant esophageal strictures. MATERIALS AND METHODS. A total of 208 patients who underwent stent placement with or without palliative radiation therapy for inoperable esophageal cancer were included. The endpoints were frequency, type, and management of airway complications; association between occurrence of airway complications and radiation therapy history; and differences in stent-to-complication interval and survival period after esophageal stenting between patients who underwent radiation therapy before and those who underwent radiation therapy after stent placement. RESULTS. Airway complications occurred in 23 patients (11.1%): 18 (78.3%) had esophagorespiratory fistula, three (13.0%) had airway narrowing, and two (8.7%) had both complications. The frequency of airway complications was significantly greater among patients who underwent RT than those who did not (p = 0.005) but was not significantly different between the radiation before stenting and radiation after stenting groups (p = 0.158). The median stent-to-complication interval and survival period after esophageal stenting were significantly shorter in the radiation before stenting group than in the radiation after stenting group (p = 0.002, p = 0.001). CONCLUSION. Esophagorespiratory fistula is much more common than airway narrowing as an airway complication. The rate of complications increases significantly in association with radiation therapy among patients with malignant esophageal stricture. Clinicians need to be aware of earlier airway complications and poorer prognosis among patients who undergo radiation therapy before placement of an esophageal stent than in patients who undergo radiation after stent placement.

E

sophageal stent placement is known to be a safe and effective procedure for treating patients with inoperable malignant esophageal strictures [1, 2]. Nevertheless, complications such as severe hemorrhage, esophageal perforation, stent migration, and esophagorespiratory fistula (ERF) have been reported in 17–46% of these patients [2–6]. Although several researchers [7, 8] have reported that previous radiation therapy (RT) and chemotherapy are not associated with increased risk of lifethreatening complications, other researchers [9–11] have reported an increased incidence of life-threatening complications associated with these therapies. In addition to airway complications, previous reports [7–12] have dealt with complications such as hemorrhage, perforation, and stent problems including stent

migration and fracture; however, the relative number of reported complications has not been large. Understanding airway complications such as ERF and airway narrowing after esophageal stenting is important because they can be fatal and require immediate management. In previous reports [7–11], the associations between airway complications and RT and between clinical outcome and airway complications were not clarified. The purpose of the study was to evaluate the effect of RT and its timing (before versus after stent placement) on airway complications in patients with inoperable esophageal malignancy who undergo esophageal stenting. We sought to evaluate the characteristics of airway complications, management of the complications, and patient survival after covered stent placement.

AJR:198, February 2012 453

Park et al.


Materials and Methods Patients Between January 1997 and December 2009, 365 patients with benign or malignant esophageal strictures were treated at our institution by place ment of a retrievable covered esophageal stent (Niti S, Taewoong). In the care of patients with malignant esophageal strictures at our institution, oncologists request consultations for RT, chemo radiation therapy, stent placement, and surgery and make the final decision about the treatment options and the order in which they are provided. Polyurethane- or polytetrafluoroethylene-covered stents were used on the basis of stent availability. Topical anesthesia of the pharynx was induced with an aerosol spray before the procedure. Patients were placed in the right lateral decubitus position. Each patient was asked to swallow a small amount of water-soluble contrast medium for opacification of the narrowed esophageal lumen. The location of the narrowed esophageal lumen was marked on the patient’s skin with radiopaque markers with fluoroscopic guidance. A 0.035-inch exchange guidewire (Radifocus M, Terumo) was inserted through the mouth across the stricture and into the stomach. A 5-French graduated sizing catheter was passed over the guidewire as far as the distal portion of the stricture to measure its length. Stents were placed with a 7-mm introducer system with fluoroscopic guidance by one of three operators in an angiography suite. Among these 365 patients, nine who underwent no follow-up imaging studies such as chest CT or esophagography, 22 with benign strictures such as corrosive strictures or postoperative strictures, and 116 with malignant strictures due to lung cancer (51 patients), stomach cancer (46 patients), breast cancer (four patients), hypopharyngeal cancer (four patients), and other forms of cancer (11 patients) were excluded. Among the other 218 patients with esophageal cancer, 10 who underwent curative RT were excluded. Therefore, a total of 208 patients with inoperable esophageal cancer were included in this study. This retrospective study was approved by our institutional review board, and the requirement for individual patient consent was waived. Airway complications were diagnosed at follow-up chest CT or esophagography. Followup esophagography was routinely performed 1–3 days and 1 and 4 weeks after stent placement. Thereafter, follow-up esophagography or CT was performed whenever clinically indicated. ERF was defined as a visible fistula track between the esophagus and the airway seen at chest CT or as visible contrast leakage from the esophagus into the airway at esophagography. Airway narrowing was symptomatic and diagnosed with CT as narrowing or obstruction of the trachea or bronchus at the

454

level of the esophageal stent and thus requiring further management.

Study Endpoints and Definitions The following were evaluated for the patients with airway complications: location of esophageal stent, management of airway complications, RT history (no RT, chemoradiation therapy, RT only), RT dose, timing of RT (RT before esophageal stent placement, RT after esophageal stent placement), stent-to-complication interval, survival data after stent placement, and cause of death. In our study, RT and stent placement were per formed for palliative purposes to manage symptoms of dysphagia. We considered RT administered when the radiation field included the area of the esophageal stent. The decision for stent placement was made when dysphagia to a soft diet was evident before or after planned palliative RT in a patient with a malignant esophageal stricture. Stenting can provide more immediate control of sudden dysphagia than can RT. The stent-to-complication interval was defined as the

time between esophageal stent placement and detection of airway complications. Overall patient survival period was defined as the time from stent placement to death or patient status on the date of the last follow-up examination. TNM category, histologic grade, and location of esophageal cancer were compared between the RT before stenting and RT after stenting groups of patients with airway complications. The endpoints of this study were frequency, type, and management of airway complications; association between the occurrence of airway complications and RT history; difference in stentto-complication interval between the RT before stenting and RT after stenting groups of patients with inoperable esophageal cancer; and the difference in survival periods after esophageal stenting between the RT before stenting and RT after stenting groups.

Statistical Analysis Data regarding the association between the occurrence of airway complications and RT were

TABLE 1: Characteristics of 23 Patients With Airway Complications Characteristic

Value

Sex (no.) Men

22

Women

1

Age Median

62

Range

33–75

Location of stent Upper esophagus

5 (21.7)

Middle esophagus

16 (69.6)

Lower esophagus

2 (8.7)

Radiation therapy No radiation therapy Chemoradiation therapy Radiation therapy only

2 (8.7) 20 (87.0) 1 (4.3)

Airway complication Esophagorespiratory fistula

18 (78.3)

Airway narrowing

3 (13.0)

Both

2 (8.7)

Cause of death Aspiration pneumonia Respiratory failure Cancer bleeding Median stent-to-complication interval (wk) Median overall survival period (mo)

15 (68.2) 4(18.2) 3 (13.6) 10 (95% CI, 2.2–17.8) 5 (95% CI, 3.1–6.9)

Note—Except for 95% CI, values in parentheses are percentages.

AJR:198, February 2012


Complications of Stent for Esophageal Stricture Fig. 1—Chart shows interventional treatment of 23 patients with airway complications. ERF = esophagorespiratory fistula.

Primary Intervention

analyzed by Fisher exact test with p < 0.05 considered significant. Differences in stent-tocomplication interval and survival period after esophageal stenting between the RT before stenting and RT after stenting groups were compared by Kaplan-Meier and log-rank tests. All statistical analysis was performed with SPSS software (version 12, SPSS).

Results Among the 208 study patients with inoperable esophageal cancer (193 men, 15 women; median age, 64.0 years; range, 33–85 years), airway complications were detected in 23 patients (11.1%; 22 men, one woman; median age, 62.0 years; range, 33–75 years) (Table 1 and Fig. 1). Eighteen patients (78.3%) had ERF (Fig. 2), three (13.0%) had narrowing of the left bronchus or trachea (Fig. 3), and two patients (8.7%) had both complications. The locations of the esophageal stents were the upper esophagus in five (21.7%), midesophagus in 16 (69.6%), and lower esophagus in two (8.7%) of the patients with airway complications. Among those without airway complications, the stents were placed in the upper esophagus in 21 (11.3%), midesophagus in 63 (34.1%), and lower esophagus in 101 (54.6%) patients. The difference between the two groups was significantly significant (p < 0.001). Twenty-two patients died, and one patient was alive at the time of this writing (Table 1). Nineteen patients underwent treatment of the airway complications (Fig. 1). Four of the 18 patients with ERF did not undergo further treatment of ERF because of their poor condition, and two underwent gastrostomy for nutritional support. Nine of the 11 patients who underwent esophageal stent placement for ERF had complete closure of the ERF and relief of aspiration symptoms. The other two had incomplete closure of the ERF and persistent aspiration symptoms. One of these nine patients with initial fistula closure experienced reopening of the fistula during follow-up that was successfully managed with stent placement in the left main bronchus. The other patient underwent management of the ERF by stent placement in both the esophagus and left main bronchus, but the fistula closure was incomplete. In three patients with airway narrowing, airway stent placement was successful, and

Esophageal stent placement (n = 11)

Secondary Intervention

Complete closure (n = 9)

One with reopening underwent left main bronchus stent placement

Incomplete closure (n = 2)

Airway stent placement + Esophageal stent placement (n = 1) with incomplete closure ERF (n = 18, 78.3%) Gastrostomy (n = 2)

No management (n = 4) 23 patients with airway complications

Narrowing (n = 3, 13.0%)

Airway stent placement with symptom improvement

Esophageal stent placement with initial success (n = 1)

Left main bronchus stent placement 4 mo. later

Jejunostomy for nutritional support (n = 1)

Left main bronchus stent placement 2 mo. later

Both (n = 2, 8.7%)

Fig. 2—69-year-old man who underwent esophageal stent placement for midesophageal cancer. A, Esophagogram 7 months after stent placement shows esophagobronchial fistula (arrows) into left main bronchus. Radiation therapy had been administered 4 weeks previously. B, Esophagogram obtained after previous covered stent (16-mm diameter) was replaced with second, larger covered stent (18 mm in diameter) shows contrast leakage has disappeared. Patient died 12 weeks after second esophageal stent placement.

dyspnea was relieved. One of the two patients with both ERF and airway narrowing underwent esophageal stent placement for ERF with successful fistula closure. Dyspnea due to left main bronchial narrowing developed 4 months later and was successfully managed with stent placement in the left main bronchus. In the other patient, the ERF was managed with jejunostomy for nutritional support. Airway stent placement for subsequent left

A

B

main bronchial narrowing was performed 2 months later, and dyspnea was relieved. RT was performed for palliative purposes in the care of 134 patients (64.4%): 71 patients in the RT before stenting group and 63 patients in the RT after stenting group. Among the 23 patients with airway complications, two (8.7%) underwent no RT, 20 (87.0%) underwent chemoradiation therapy, and one (4.3%) underwent RT only (Table 1). Among the 21



Park et al. Fig. 3—70-year-old man who underwent esophageal stent placement (18-mm diameter) for esophageal cancer. Radiation therapy had been administered 8 months before esophageal stent placement. A, CT scan 6 weeks after esophageal stent placement shows marked narrowing of lower trachea (arrow) caused by expanded esophageal stent. B, Esophagogram shows appearance after covered stent (20-mm diameter) (arrows) was placed in lower trachea. C, Follow-up chest CT scan shows markedly improved luminal patency of trachea due to expanded tracheal stent (arrow). Dyspnea improved, but patient died 10 weeks after tracheal stent placement.

A patients who had airway complications and underwent either chemoradiation therapy or RT alone, eight patients underwent RT before stenting and 13 underwent RT after stenting (Table 2). The median interval between RT and stent-

B

C

ing was 17 weeks (95% CI, 11.5–22.5 weeks), and the median interval between stenting and RT was 7 weeks (95% CI, 4.5–9.5 weeks). The frequency of airway complications was significantly higher among patients who

TABLE 2: Comparison of Characteristics Before and After Radiation Therapy in 21 Patients With Airway Complications Value Radiation Before Stenting (n = 8)

Radiation After Stenting (n = 13)

Men

8

12

Women

0

1

Characteristic Sex

Age Median

61

66

Range

49–74

33–75

II

2 (25.0)

1 (7.7)

III

3 (37.5)

5 (38.5)

IV

3 (37.5)

7 (53.8)

Esophagorespiratory fistula

5 (62.5)

12 (92.3)

Airway narrowing

2 (25.0)

0

Both

1 (12.5)

1 (7.7)

6

21

Aspiration pneumonia

6 (75.0)

8 (61.5)

Respiratory failure

2 (25.0)

2 (15.4)

0

3 (23.1)

2

7

Stage of disease

Airway complication

Median stent-to-complication interval (wk) Cause of death

Cancer bleeding Median overall survival period (mo) Note—Values in parentheses are percentages.

456

underwent RT (15.7%, 21/134) than those who did not (2.7%, 2/74) (p = 0.005) (Tables 3 and 4). The frequency of airway complications did not differ in the two groups (p = 0.158) (Table 4). The median radiation dose to 21 patients was 4800 cGy (range, 2800–6000 cGy). The initial disease stage in the RT before stenting and the RT after stenting groups with airway complication did not differ significantly in this study (p = 0.367). Histologic grade and location of the tumor were not statistically different between the groups (p = 0.706, p = 1.000). The median stent-to-complication interval was 10 weeks (95% CI, 2.2–17.8 weeks) for the 23 patients with airway complications. Among these 23 patients, the median stent-tocomplication interval for the RT before stenting group (6 weeks [95% CI, 4.7–7.3 weeks]) was significantly shorter than that for the RT after stenting group (21 weeks [95% CI, 16.9– 25.1 weeks]) (p = 0.002) (Fig. 4A). The median overall survival period of the 23 patients was 5 months (95% CI, 3.1–6.9 months). The survival period after stent placement in the RT before stenting group (2 months [95% CI, 0.6– 3.4 months]) was significantly shorter than that in the RT after stenting group (7 months [95% CI, 3.5–10.5 months) (p = 0.001) (Fig. 4B). Discussion RT is used before surgery to downstage esophageal cancer; it is also used as a palliative tool. Palliative RT is known to be effective in the care of 60–80% of patients with esophageal cancer [12]. Despite such potential benefit, several reports have described an increased rate of stent-related complications


Complications of Stent for Esophageal Stricture


TABLE 3: Relation Between Airway Complications and Radiation Therapy in 208 Patients With Esophageal Stents Radiation Therapy Airway Complication

Performed

Not Performed

Total

Present

21

2

23

Absent

113

72

185

Total

134

74

208

p

0.005

Note—Fisher exact test.

TABLE 4: Relation Between Airway Complications and Timing of Radiation Therapy Among 134 Patients Undergoing Radiation Therapy Timing Airway Complication

Radiation Before Stenting

Radiation After Stenting

Total

Present

8

13

21

Absent

63

50

113

Total

71

63

134

p

0.158

Note—Fisher exact test.

when RT with or without chemotherapy is combined with stent placement [9–11]. In this study, we focused on airway complications after esophageal stent placement with special reference to RT. In our study, airway complications occurred after esophageal stent placement in 11.1% of patients with malignant esophageal strictures. Midesophageal stents were associated with a higher frequency of airway complications because of their proximity to the airway. This rate seems to be higher than in previous reports, in which the frequency was 0–6% [7–11]. Because potentially clinically silent complications were not detected more than 4 weeks after stent placement in this study, our frequency of airway complications might have been underestimated. Considering that the median stent-to-complication interval was 10 weeks and the median survival period was 5 months in our study, these airway complications tend to occur in the middle of the follow-up period after stent placement. Because ERF and airway narrowing are potentially fatal complications associated with early mortality and morbidity, prompt diagnosis and treatment are crucial [13, 14]. Therefore, patients who have undergone RT should be informed of the increased risk of stent-related airway complications. Our study showed that RT was significantly associated with the occurrence of airway complications after esophageal stent placement in patients with malignant esophageal strictures. This result is similar to those achieved in several previous studies involv-

ing 59–200 patients [7–11]. Kinsman et al. [9] reported an increased rate of life-threatening complications among patients who underwent Z-stent placement in addition to chemotherapy, RT, or both [9]. Among 59 patients who underwent esophageal stent placement, the frequency of life-threatening complications was significantly higher among patients who underwent RT or chemotherapy than among patients who did not undergo RT or chemotherapy (36.4% vs 2.5%). Mortality was also significantly higher (23% vs 0%) among patients who underwent RT or chemotherapy. Lecleire et al. [10] reported that patients with major complications had received a significantly higher radiation dose than had patients without major complications (55.9 vs 45.9 Gy, p = 0.007). Siersema et al. [11] reported increased risk of specific device-related complications, such as bleeding, perforation, fever, fistula, and severe pain, related to previous RT or chemotherapy. The cause of the increased risk of complications among patients who undergo previous RT or chemotherapy is likely to be multifactorial. Radiation is known to cause esophageal injury such as esophagitis and ulceration. Esophageal perforation and ERF may also result from radiation-induced vasculitis and injury [9, 15, 16]. Tumor-related necrosis and ulceration also may be contributing factors. Pressure necrosis may be an important factor when a stent is placed in a patient who has undergone previous RT or chemotherapy [9]. Metal stent placement is often followed by progressive embedding of

the stent in the esophageal wall [17] in association with localized necrosis due to pressure of the stent on esophageal tissue. Cwikiel et al. [18] and Silvis et al. [19] reported that in animal models, metal stents became embedded deep into the muscularis propria with a substantial depth of necrosis and fibrosis. In patients who have undergone RT, a metal stent can become more deeply embedded in the injured esophageal wall, causing perforation or ERF [10]. A stent also can cause dose perturbation during RT owing to hot and cold spots in the esophageal mucosa and can affect the incidence and severity of RT-related side effects [20]. Some researchers [7, 8] have suggested that there is no correlation between previous RT or chemotherapy and complications after stent placement. Raijman et al. [8] suggested that in their study involving 60 patients there was no correlation between previous RT or chemotherapy and complications after stent placement. Homs et al. [7] reported that the incidence of life-threatening complications was not higher among patients with previous RT or chemotherapy (29% vs 21%) on the basis of results in the care of 200 patients with esophagogastric carcinoma. The controversial outcomes in previous reports [7–11] can be explained by several points. First, different study patients and protocols were used in the previous reports. For example, only patients with inoperable esophageal cancer were included in our study. Second, previous reports included all complications in addition to airway involvement and different definitions of complications. Last, stents of different shapes and physical characteristics were used. Our study showed that patients who underwent RT before stent placement had a significantly shorter stent-to-complication interval and a shorter survival period than those who underwent RT after stent placement. We attempted to minimize bias between the two groups by including only patients with inoperable esophageal cancer with or without palliative RT and by showing no difference in cancer staging in the two groups. This observation can be partially explained by the poor prognosis among patients in whom dysphagia develops, requiring stent placement for tumor regrowth or disease progression after RT, even though the initial cancer stages may not differ in the two groups [10]. Song et al. [21] reported that patients who underwent RT after stent placement had a significantly longer survival period but


1.0

1.0

0.8

0.8

0.6

0.6

p

p


Park et al.

0.4

0.4

0.2

0.2

0.0

0.0 0

20

40

60

80

100

120

0

Stent-to-Complication Interval (wk)

5

10

15

20

25

30

Post Stent Survival (mo)

A

B

Fig. 4—Statistical significance of difference between radiation before stenting (solid line) and radiation after stenting (dashed line) groups of patients with esophageal cancer. A, Graph shows results for stent-to-complication interval. B, Graph shows results for survival period after stent placement.

substantially more complications than those who underwent RT before stent placement or who did not undergo RT. In our study, the incidence of airway complications did not differ between the RT before stenting and RT after stenting groups. It is difficult to directly compare our results with those of Song et al. because we specifically focused on airway complications. The observation that airway complications occurred earlier in the RT before stenting group indicates that clinicians need to watch for signs of complications in stent patients who have undergone RT. To decrease the rate of airway complications after esophageal stenting in patients who undergo RT, temporary placement of a covered retrievable stent for 4 weeks with concurrent RT may be more beneficial for reducing complications and the risk of related reintervention than may permanent stent placement [22]. Biodegradable self-expandable stents might be used to achieve a temporary stenting effect because they have been reported in the management of benign and malignant esophageal strictures [23]. Biodegradable stents may be used as an alternative to gastrostomy and temporary stenting during RT or chemotherapy in patients with esophageal cancer [23]. In our study, management of airway complications was possible in most patients. Patients with ERF were treated with another esophageal or airway stent placement or gastrostomy tube insertion because of the risk of aspiration after oral intake. The choice of esophageal or air-

458

way stent depends on the degree of airway or esophageal stenosis and the presence of related symptoms such as dysphagia and dyspnea. For patients with airway narrowing, a tracheal or bronchial stent would be the first choice. Interventional treatment was effective for palliation of airway complications. Our study had several limitations. First, although our study was based on the records of a large number of patients who underwent esophageal stent placement for malignant esophageal strictures, it was retrospective. Stent placement was chosen because the patients had dysphagia. The timing of RT in relation to stent placement can affect survival [21]. Second, the two groups had small numbers of patients. Therefore, bias was maximally avoided by confining the underlying disease to inoperable esophageal cancer with or without palliative RT and by showing no difference in initial tumor staging between the two groups. Third, we considered the initial stage of cancer a surrogate to tumor biology not the tumor response to treatment. Fourth, the contribution of RT to airway complications was not quantitatively analyzed, and stent type and diameter and stricture length were not assessed. Comparison between patients with and those without airway complications and comprehensive review of complications are necessary for future research. In conclusion, palliative RT may be associated with a high frequency of airway complications after esoph-

ageal stenting in patients with inoperable malignant strictures. ERF was much more common than airway narrowing, and airway complications were managed successfully in many patients. Clinicians need to be aware that airway complications are likely to occur earlier in patients who undergo RT before stenting than in those who undergo RT after stenting. Patients who undergo RT before stenting may have a shorter survival period after stent placement. Acknowledgment We thank Bonnie Hami, Department of Radiology, University Hospitals of Cleveland, for editorial assistance in the preparation of the manuscript. References 1. Winkelbauer FW, Schofl R, Niederle B, Wildling R, Thurnher S, Lammer J. Palliative treatment of obstructing esophageal cancer with nitinol stents: value, safety, and long-term results. AJR 1996; 166:79–84 2. Tomaselli F, Maier A, Sankin O, Pinter H, Smolle J, Smolle-Juttner FM. Ultraflex stent: benefits and risks in ultimate palliation of advanced, malignant stenosis in the esophagus. Hepatogastroenterology 2004; 51:1021–1026 3. Muto M, Ohtsu A, Miyata Y, Shioyama Y, Boku N, Yoshida S. Self-expandable metallic stents for patients with recurrent esophageal carcinoma after failure of primary chemoradiotherapy. Jpn J Clin Oncol 2001; 31:270–274 4. Ott C, Ratiu N, Endlicher E, et al. Self-expanding



Complications of Stent for Esophageal Stricture Polyflex plastic stents in esophageal disease: various indications, complications, and outcomes. Surg Endosc 2007; 21:889–896 5. Javed A, Pal S, Dash NR, et al. Palliative stenting with or without radiotherapy for inoperable esophageal carcinoma: a randomized trial. J Gastrointest Cancer 2010 Sep 14 [Epub ahead of print] 6. Burstow M, Kelly T, Panchani S, et al. Outcome of palliative esophageal stenting for malignant dysphagia: a retrospective analysis. Dis Esophagus 2009; 22:519–525 7. Homs MY, Hansen BE, van Blankenstein M, Haringsma J, Kuipers EJ, Siersema PD. Prior radiation and/or chemotherapy has no effect on the outcome of metal stent placement for oesophagogastric carcinoma. Eur J Gastroenterol Hepatol 2004; 16:163–170 8. Raijman I, Siddique I, Lynch P. Does chemoradiation therapy increase the incidence of complications with self-expanding coated stents in the management of malignant esophageal strictures? Am J Gastroenterol 1997; 92:2192–2196 9. Kinsman KJ, DeGregorio BT, Katon RM, et al. Prior radiation and chemotherapy increase the risk of life-threatening complications after insertion of metallic stents for esophagogastric malignancy. Gastrointest Endosc 1996; 43:196–203 10. Lecleire S, Di Fiore F, Ben-Soussan E, et al. Prior chemoradiotherapy is associated with a higher life-threatening complication rate after palliative

insertion of metal stents in patients with oesophageal cancer. Aliment Pharmacol Ther 2006; 23: 1693–1702 11. Siersema PD, Hop WC, Dees J, Tilanus HW, van Blankenstein M. Coated self-expanding metal stents versus latex prostheses for esophagogastric cancer with special reference to prior radiation and chemotherapy: a controlled, prospective study. Gastrointest Endosc 1998; 47:113–120 12. Caspers RJ, Welvaart K, Verkes RJ, Hermans J, Leer JW. The effect of radiotherapy on dysphagia and survival in patients with esophageal cancer. Radiother Oncol 1988; 12:15–23 13. Libby ED, Fawaz R, Leano AM, Hassoun PM. Airway complication of expandable stents. Gastrointest Endosc 1999; 49:136–137 14. Wang MQ, Sze DY, Wang ZP, Wang ZQ, Gao YA, Dake MD. Delayed complications after esophageal stent placement for treatment of malignant esophageal obstructions and esophagorespiratory fistulas. J Vasc Interv Radiol 2001; 12:465–474 15. Seaman WB, Ackerman LV. The effect of radiation on the esophagus; a clinical and histologic study of the effects produced by the betatron. Radiology 1957; 68:534–541 16. Vanagunas A, Jacob P, Olinger E. Radiation-induced esophageal injury: a spectrum from esophagitis to cancer. Am J Gastroenterol 1990; 85: 808–812 17. Bethge N, Sommer A, Gross U, von Kleist D, Va-

kil N. Human tissue responses to metal stents implanted in vivo for the palliation of malignant stenoses. Gastrointest Endosc 1996; 43:596–602 18. Cwikiel W, Willen R, Stridbeck H, Lillo-Gil R, von Holstein CS. Self-expanding stent in the treatment of benign esophageal strictures: experimental study in pigs and presentation of clinical cases. Radiology 1993; 187:667–671 19. Silvis SE, Sievert CE Jr, Vennes JA, Abeyta BK, Brennecke LH. Comparison of covered versus uncovered wire mesh stents in the canine biliary tract. Gastrointest Endosc 1994; 40:17–21 20. Atwood TF, Hsu A, Ogara MM, et al. Radiotherapy dose perturbation of esophageal stents examined in an experimental model. Int J Radiat Oncol Biology Phys 2011 Apr 20 [Epub ahead of print] 21. Song HY, Lee DH, Seo TS, et al. Retrievable covered nitinol stents: experiences in 108 patients with malignant esophageal strictures. J Vasc Interv Radiol 2002; 13:285–293 22. Shin JH, Song HY, Kim JH, et al. Comparison of temporary and permanent stent placement with concurrent radiation therapy in patients with esophageal carcinoma. J Vasc Interv Radiol 2005; 16:67–74 23. Stivaros SM, Williams LR, Senger C, Wilbraham L, Laasch HU. Woven polydioxanone biodegradable stents: a new treatment option for benign and malignant oesophageal strictures. Eur Radiol 2010; 20:1069–1072
