Colonic stenting for colorectal cancer: stoma avoidance with acceptable radiation exposure

Abstract

Background/Aims

Self-expanding metal stents (SEMS) are used to manage colonic obstruction for palliative decompression or as a bridge to curative surgery and are typically placed under fluoroscopic guidance. This study aimed to quantify the radiation exposure associated with colonic stenting for obstructing colorectal cancer (CRC) and compare it with established diagnostic reference levels (DRLs) for similar fluoroscopy-guided procedures. Secondary outcomes included procedural success rates, stent patency, stoma rates, and complications.

Methods

This retrospective observational study was conducted at a single district general hospital and included all the patients who underwent colonic stenting for CRC between March 2016 and February 2021. Radiation exposure was measured using the kerma-area product (KAP) in µGy*m² and fluoroscopy time in minutes, obtained from existing electronic patient records.

Results

Fifty-two stenting procedures were performed in 47 patients. Median KAP was 1,373.7 (interquartile range [IQR], 584.4–3,185.2) µGy*m², and fluoroscopy time was 8.9 (IQR, 4.4–12.6) minutes. Technical and clinical success was achieved in 86.5% of the cases. In palliative cases, 88.9% of patients maintained stent patency until death. The complications included perforation (5.8%) and stent migration (3.9%). Laparoscopic surgery was performed in 70% of curative cases.

Conclusions

Radiation exposure during colonic stenting is within acceptable ranges and comparable to that of other fluoroscopy-guided procedures. These findings support the listing of colonic stenting in future National DRLs in the United Kingdom.

Graphical abstract

INTRODUCTION

More than 28,000 new cases of colorectal cancer (CRC) are diagnosed each year in the United Kingdom (UK).1 Up to 14% to 30% of these patients present as an emergency with acute colonic obstruction,1 and traditionally, these patients would undergo emergency surgery. However, the insertion of self-expanding metal stents (SEMS) has emerged as a minimally invasive alternative, endorsed by the National Institute of Health and Care Excellence,2 either as a palliative treatment or as a bridge to elective surgery. Colonic stenting offers clinical advantages, including reduced stoma rates3,4 and improved oncological outcomes,5 potentially due to the opportunity for comprehensive cancer staging and medical optimization prior to elective surgery. Procedure-specific risks include perforation, hemorrhage, stent migration, and re-obstruction.3,4

One important yet under-researched aspect is radiation exposure involved in the procedure. Colonic stenting is typically guided by fluoroscopy, which, similar to other interventional radiological procedures, uses ionizing radiation to visualize stent placement in real time. Radiation exposure poses deterministic risks, such as tissue damage, and stochastic risks, including an increased long-term risk of malignancy.6 Given that radiation doses can vary depending on the length and complexity of the procedure, optimization of patient protection is essential. International guidelines, such as those provided by the International Commission on Radiological Protection and the International Atomic Energy Agency, emphasize the importance of diagnostic reference levels (DRLs) to ensure that radiation doses remain as low as reasonably achievable during medical procedures.7

However, to date, there is a scarcity of published studies that have specifically quantified the radiation exposure in patients undergoing colonic stenting for malignant obstruction, making this a key area for further investigation. Our study aimed to address this gap by quantifying the radiation dose to which patients are exposed to during colonic stent insertion for obstructing CRC. Additionally, secondary outcomes including the stent’s effectiveness in maintaining patency, stoma rates, procedure-related complications, and rates of laparoscopic versus open surgery following stenting were assessed.

METHODS

Study design

This retrospective observational study was conducted at a single urban district general hospital (Princess Royal University Hospital, King’s College NHS Foundation Trust, UK). The study included all patients who underwent colonic stenting for CRC between the 1st of March 2016 and the 1st of February 2021. The primary aim was to quantify the radiation exposure during the stenting procedure, while the secondary outcomes focused on procedural success, freedom from obstruction, stoma rate, and related complications.

Patient selection

Eligible participants were identified from hospital records using the procedure codes for colonic stenting. The inclusion criteria comprised all consecutive adult patients with a confirmed diagnosis of CRC who underwent colonic stenting for clinically or radiologically confirmed acute or impending large-bowel obstruction during the study period. Patients with incomplete medical records or those who underwent stenting for non-malignant indications were excluded.

Data collection

Data were extracted from electronic health records with a minimum follow-up period of two years post-stent insertion. The collected variables included patient demographics (age and sex) and baseline functional status (World Health Organization performance status score). Cancer-related data included the date of diagnosis, initial diagnostic modality, tumor site, and histological characteristics.

Details of the stenting procedure were documented, including the date of stent insertion, treatment intent (curative or palliative), time from diagnosis to stenting, success rate (defined as both technical success in stent placement and clinical resolution of the obstruction), and radiation exposure recorded during the procedure. Radiation exposure was measured as kerma-area product (KAP), expressed in µGy*m², along with the fluoroscopy time, measured in minutes.

Additional outcome measures included stent-related complications such as perforation, stent migration, hemorrhage, and recurrence of obstruction. Details of subsequent surgeries were also collected, including whether a laparoscopic or open approach was used, whether resection was performed, the presence of a stoma, subsequent stoma reversal, and the time to surgery. Morbidity and mortality data, including in-hospital morbidity, mortality, and date of death, were also recorded.

All data were anonymised and securely stored in compliance with the King’s College Hospital NHS Foundation Trust guidelines.

Radiation exposure measurement

Radiation exposure during colonic stenting was quantified using the KAP, which measures the total radiation dose delivered during the procedure. KAP values were expressed in µGy*m² and obtained from the fluoroscopy system’s dose-monitoring software, which records radiation exposure for all fluoroscopy-guided procedures. In addition to the KAP, the total fluoroscopy time for each procedure, measured in minutes, was recorded to provide further insight into radiation use. These metrics enable comprehensive assessment of the radiation burden associated with colonic stenting.

Statistical analysis

Statistical analyses were performed using GraphPad Prism ver. 10.0.0 for Windows (GraphPad Software; www.graphpad.com).

Ethical approval

The UK National Research Ethics Service Decision Tool (http://www.hra-decisiontools.org.uk) confirmed that this study did not require ethical approval. It is registered locally within the King’s College Hospital NHS Foundation Trust as a clinical audit.

RESULTS

Patient demographics and clinical characteristics

During the study period (March 2016–February 2021), 52 colonic stenting procedures were performed in 47 patients diagnosed with acute or impending colonic obstruction secondary to CRC. Patient demographics and clinical characteristics are summarized in Table 1.

Table 1.

Demographic and clinical characteristics of patients who underwent colonic stenting for colorectal cancer

Characteristic	Value
Total no. of patients	47 (100)
Male	29 (61.7)
Age (yr)	74 (60–87)
World Health Organization performance status
0–2	32 (68.1)
3–4	12 (25.5)
Not recorded	3 (6.4)
Initial diagnostic modality
Computed tomography	36 (76.6)
Colonoscopy	10 (21.3)
Flexible sigmoidoscopy	1 (2.1)
Time from initial diagnosis to stenting (day)	22 (5–40)
Histopathological cancer type
Adenocarcinoma	47 (100)
Tumor site
Transverse colon	2 (4.3)
Descending colon	5 (10.6)
Sigmoid colon	27 (57.4)
Rectosigmoid	8 (17.0)
Rectum	5 (10.6)

Values are presented as number (%) or median (interquartile range).

Radiation exposure

Five patients underwent two colonic stenting procedures, bringing the total number of procedures to 52. The fluoroscopy time was available for 42 of these procedures. The median fluoroscopy time was 8.9 minutes (interquartile range [IQR], 4.4–12.6 minutes; Fig. 1A). Radiation exposure data in terms of KAP were available for 46 procedures. The median KAP was 1,373.7 µGy*m² (IQR, 584.4–3,185.2 µGy*m²; Fig. 1B).

Fig. 1.

(A) Fluoroscopy time (min) for colonic stenting procedures. (B) Radiation exposure measured during the study (kerma-area product in μGy*m²).

Complications and clinical outcomes

Of the 52 colonic stenting procedures, 45 (86.5%) were technically and clinically successful, achieving both technical stent placement and the clinical resolution of bowel obstruction. Seven patients had an unsuccessful procedure: one with an inability to cannulate the lumen, one with mucosal bleeding, two with early stent migration, and three with an impression of microperforation. Of these, three patients underwent stent reinsertion, while four required emergency stoma formation.

Of the 52 procedures, 11 were performed with curative intent as a bridge to surgery and 41 were performed with palliative intent. Among the patients treated with curative intent, 10 of 11 (90.9%) underwent surgery. The median time from stenting to surgery was 110.5 days (IQR, 22–272 days). Of the 10 operations, seven were initiated laparoscopically (one converted to open) and three were performed as open surgeries. A stoma was created in six of these 10 patients, and one of the six stomas was reversed during the two-year follow-up period, with some stoma patients awaiting reversal of stoma (i.e., still on the elective waiting list) to date.

Of the 36 patients treated with palliative intent, four (11.1%) presented with recurrent obstruction within the two-year follow-up period. The remaining 32 patients (88.9%) died with patent stents and were free from obstruction.

At the end of the follow-up period, stoma formation had been avoided in 37 patients (78.7%). The overall mortality rate was 76.6% at the end of follow-up (87% of patients were treated with palliative intent), and the median time from stenting to death was 174 days (IQR, 75–362.5 days). Kaplan-Meier survival analysis showed no statistical difference between actual survival and freedom from obstruction (log-rank Mantel-Cox test: chi-square, 0.5654; p=0.4521), indicating that palliative patients treated with SEMS died with a patent stent (Fig. 2).

Fig. 2.

Kaplan-Meier curves between patient mortality (red line) and freedom from intestinal obstruction (blue line) were not significantly different, i.e. patients died with a patent stent (log-rank Mantel-Cox test: chi-square, 0.5654; p=0.4521).

DISCUSSION

This retrospective study provides important insights into radiation exposure and clinical outcomes of patients undergoing colonic stenting for obstructing CRC. The median KAP of 1,373.7 µGy*m² and median fluoroscopy time of 8.9 minutes reflect the radiation burden during the procedure. Colonic stenting demonstrated high technical and clinical success rates (86.5%) and was effective in maintaining stent patency in palliative cases, with a low recurrence of obstruction (11.1%).

Currently, there is no officially accepted UK DRL for colonic stenting. The National DRLs set by the UK Health Security Agency (UKHSA) provide reference standards for several fluoroscopy-guided procedures; however, colonic stenting has not yet been included in this list.8 Given the increasing adoption of colonic stenting, this procedure warrants closer consideration for formal inclusion in the National DRL framework.

To contextualize our results, we compared radiation exposure in our study with the UK DRLs for similar procedures. For example, the UKHSA lists a DRL for esophageal stenting with a KAP of 1,300 µGy*m² and a fluoroscopy time of 5 minutes.8 Our study’s median KAP of 1,373.7 µGy*m² and a fluoroscopy time of 8.9 minutes fall in line with these benchmarks, suggesting that the radiation burden for colonic stenting is acceptable. This comparison indicates that colonic stenting carries a manageable radiation burden, comparable to that of other established fluoroscopy-guided procedures. Table 2 provides a comparison of our findings with those of the UKHSA DRL standards for similar procedures.8 Based on these findings, we propose that colonic stenting should be considered for inclusion in the UKHSA DRL list as its use continues to expand.

Table 2.

Comparison with national diagnostic reference levels set by the UK Health Security Agency diagnostic reference levels for interventional fluoroscopy-guided abdominal procedures8

Procedure	Kerma-area product per exam (µGy*m²)	Fluoroscopy time (min)
Colonic stenting (current study)	1,373.7	8.9
Esophageal stenting	1,300	5
Nephrostomy	1,300	6.7
Biliary intervention	4,300	14

The success rate of 86.5% in our study is consistent with that reported in the literature, which range from 80-95%.3,9,10 Similarly, complications in our study, including perforation (5.8%) and stent migration (3.9%), were consistent with those observed in other studies.3,9 These results support the continued use of colonic stenting as a safe and effective method for managing obstructive CRC in both palliative and curative settings. Published evidence on radiation exposure during colonic stenting is scarce. In an early report from 2004, De Gregorio and colleagues reported a median fluoroscopy time of 20.9 minutes and radiation exposure (KAP) of 35,930 µGy*m².11 These high values may represent an early learning curve and less-efficient fluoroscopic hardware. At the time of revision of this manuscript, Tamaru et al.12 reported longer median fluoroscopy time (12.6 minutes) and higher median radiation exposure (KAP of 2,270 µGy*m²) compared to our results, but within the same order of magnitude, essentially confirming our findings.

Colonic stenting in our cohort successfully facilitated laparoscopic surgery in 70% of the patients treated with curative intent. This is particularly important because laparoscopic surgery is associated with faster recovery and reduced morbidity.13 In palliative cases, the procedure effectively maintained bowel patency in 88.9% of the patients, improving the quality of life by avoiding recurrent obstruction. These findings highlight the value of colonic stenting in improving the outcomes of elective surgery, while also providing an effective palliative option for patients with advanced CRC.

Our study has some limitations. First, the retrospective design introduced potential biases, including selection bias and missing or incomplete data, which may have affected the generalizability of the findings. Radiation exposure data were available for 42 of the 52 colonic stenting procedures included in the study. As this was a retrospective study, it was not possible to recover missing data, which may have introduced bias. Specifically, if procedures without recorded radiation exposure include particularly long or short procedures, the calculated median KAP and fluoroscopy time could be skewed. Although the available data provide valuable insights, the potential for selection bias should be considered when interpreting the results.

Additionally, the study was conducted at a single center, and the results may not fully represent other clinical settings or practices. Furthermore, the absence of a formal control group limited our ability to directly compare outcomes with other management strategies, such as emergency surgery. While this limitation is acknowledged, it aligns with the study’s focus on radiation exposure in colonic stenting rather than a comparison with other interventions. Existing trials, such as the Colorectal Endoscopic Stenting Trial (CReST),3 have already explored these alternative management strategies; however, their scope falls outside the specific aims of this study. In conclusion, our findings indicate that radiation exposure during colonic stenting is within acceptable ranges when compared to those with similar fluoroscopy-guided interventional procedures. This provides strong evidence that colonic stenting is a safe procedure in terms of radiation risk and supports its consideration for inclusion in future National DRLs in the UK. Additionally, colonic stenting is a safe and effective treatment option that avoids stoma formation for obstructing CRC, with high success rates in both curative and palliative settings.

As to our knowledge, this is the first study to examine radiation exposure during colonic stenting, these findings provide an important foundation for future research. However, prospective multicenter studies are required to validate these results on a larger scale.