Usefulness and safety of 0.4% sodium hyaluronate solution as a submucosal fluid "cushion" for endoscopic resection of colorectal mucosal neoplasms: A prospective multi-center open-label trial
- Shoji Hirasaki†1Email author,
- Takahiro Kozu†2,
- Hironori Yamamoto†3,
- Yasushi Sano†4,
- Naohisa Yahagi†5,
- Tsuneo Oyama†6,
- Tadakazu Shimoda7,
- Kentaro Sugano3,
- Hisao Tajiri8,
- Takao Takekoshi9 and
- Daizo Saito10
© Hirasaki et al; licensee BioMed Central Ltd. 2009
Received: 29 January 2008
Accepted: 08 January 2009
Published: 08 January 2009
Sodium hyaluronate (SH) solution has been used for submucosal injection in endoscopic resection to create a long-lasting submucosal fluid "cushion". Recently, we proved the usefulness and safety of 0.4% SH solution in endoscopic resection for gastric mucosal tumors. To evaluate the usefulness of 0.4% SH as a submucosal injection solution for colorectal endoscopic resection, we conducted an open-label clinical trial on six referral hospitals in Japan.
A prospective multi-center open-label study was designed. A total of 41 patients with 5–20 mm neoplastic lesions localized in the colorectal mucosa at six referral hospitals in Japan in a single year period from December 2002 to November 2003 were enrolled and underwent endoscopic resection with SH. The usefulness of 0.4% SH was assessed by the en bloc complete resection and the formation and maintenance of mucosal lesion-lifting during endoscopic resection. Safety was evaluated by analyzing adverse events during the study period.
The usefulness rate was high (82.5%; 33/40). The following secondary outcome measures were noted: 1) steepness of mucosal lesion-lifting, 75.0% (30/40); 2) intraoperative complications, 10.0% (4/40); 3) time required for mucosal resection, 6.7 min; 4) volume of submucosal injection, 6.8 mL and 5) ease of mucosal resection, 87.5% (35/40). Two adverse events of bleeding potentially related to 0.4% SH were reported.
Using 0.4% SH solution enabled sufficient lifting of a colorectal intramucosal lesion during endoscopic resection, reducing the need for additional injections and the risk of perforation. Therefore, 0.4% SH may contribute to the reduction of complications and serve as a promising submucosal injection solution due to its potentially superior safety in comparison to normal saline solution.
The incidence of colorectal neoplasm in Japan is high, and the number of patients with colorectal neoplasm is steadily increasing. The chances of treating colorectal mucosal lesion with endoscopy have increased [1–3]. Depending on techniques and equipment, endoscopic resection of the colon includes polypectomy, endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) in the colon. Focusing on the physiochemical properties of sodium hyaluronate (SH), Yamamoto et al. developed a technique known as EMR using sodium hyaluronate (EMRSH), and reported that when SH was injected into the submucosal layer during EMR, mucosal lesions could be adequately lifted for a sufficient duration to allow safe, reliable, and complete resection without SH diffusion or absorption by the submucosal layer [4, 5]. Recently, we proved the usefulness and safety of 0.4% SH solution in endoscopic resection for gastric mucosal tumors . To evaluate the usefulness of 0.4% SH as a submucosal injection solution for colorectal endoscopic resection, we conducted an open-label clinical trial on six referral hospitals in Japan.
The target population of the study was consecutive patients who visited six referral hospitals in Japan from December 2002 to November 2003 on an outpatient basis for colorectal mucosal neoplasms that could be treated endoscopically. All patients underwent confirmation colonoscopy within 4 weeks before endoscopic resection. If a patient had already undergone colonoscopy within 4 weeks before informed consent, the data for that colonoscopy was used as part of the study data to avoid another colonoscopy, thereby minimizing stressful procedures for the patient. The present study was explained to those meeting the following criteria, and informed consent was obtained from 44 patients. Three patients were excluded for meeting the exclusion criteria and the remaining 41 patients were enrolled.
Inclusion criteria consisted of the following: a neoplastic lesion 5–20 mm in diameter localized to the colorectal mucosa; indication for endoscopic resection; and patient age between 20 and 80 years. We limited the size of the neoplasms because the guidelines for the Japanese Society for Cancer of the Colon and Rectum  state that neoplasms of ≤ 20 mm in diameter can be completely resected en bloc.
Exclusion criteria included: 1) residual or recurrent lesion, 2) lesion accompanied by ulceration, 3) submucosal invasion, 4) pacemaker, 5) advanced malignant neoplasm, 6) history of hypersensitivity to SH, 7) systemic administration of an anticancer agent, 8) severe liver, kidney or cardiovascular disease; 9) pregnancy or lactation, or women who wished to become pregnant during the study and 10) patients judged to be inappropriate for inclusion by a physician.
The present study was conducted in compliance with the Helsinki Declaration and Good Clinical Practice (GCP). The institutional review boards (IRB) of all of the participating institutions (the IRB of Shikoku Cancer Center, the IRB of National Cancer Center Hospital, the IRB of Jichi Medical University, the IRB of Tokyo University, and the IRB of Saku General Hospital) approved all study protocols. Written informed consent was obtained from all patients.
For 7 days before and after endoscopic resection, the use of anticoagulants and antiplatelets that can induce bleeding during endoscopic resection or from the surgical wound, or drugs contraindicated in the treatment of peptic ulcer, were prohibited. During endoscopic resection, the submucosal injection of agents that could affect the assessment of 0.4% SH, such as saline, 3.7% hypertonic saline, 50% glucose and 10% glycerol were prohibited. Except for epinephrine and indigo carmine, nothing was added to submucosal injection solutions. However, the concentrations for epinephrine and indigo carmine were not stipulated as a part of the protocol. Furthermore, medication was allowed to treat coexisting disorders not included in the above and which occurred ≥ 4 weeks before endoscopic resection as well as adverse events that occurred during the study.
A solution of 0.4% SH was prepared by dissolving SH (manufactured by Seikagaku Corp, Tokyo, Japan) to a concentration of 0.4% (w/v), the solution was then placed in a 20 mL glass vial and stored at room temperature. The upper limit of 0.4% SH submucosal injection was 40 mL, which is one-tenth of the nontoxic level with intraperitoneal administration, and an appropriate amount was used in each patient.
Primary outcome measure
Complete en bloc resection
Incomplete or Not evaluable
Statistical analysis and outcomes
As a general rule, the full analysis set (FAS) comprised all patients who underwent endoscopic resection. All analyses were performed using SAS software (SAS Institute, Cary, North Carolina, USA). Intergroup comparisons were conducted as follows.
Usefulness and safety were described by calculating 95% confidence intervals using the binomial method. Values of p < 0.05 were considered statistically significant. The Wilcoxon two-sample test for continuous outcomes and Fisher's exact test for binary outcomes were used. For clinical laboratory test findings, the McNemar test was used to assess changes before and after endoscopic resection.
Endoscopic resection was clinically assessed based on en bloc complete resection as determined by histopathological analysis of the neoplastic lesions. The reported rate of en bloc complete resection with normal saline as the submucosal injection solution is 72.9–85% [16–18]. From this, when the rate of en bloc complete resection for the 0.4% SH was set at 90%, a sample size of 35 patients was required in order to meet the hypothesized rate of 90% resection with a 95% confidence interval of the length ± 10%. The established target number of patients for 0.4% SH, allowing for potential dropouts, was 42.
Demographic characteristics of the 40 patients at baseline
Characteristic (n = 40)
45 – 80
Sex [n (%)]
Location of neoplasm [n (%)]
Macroscopic classification † [n (%)]
Laterally spreading tumor
Neoplasm size [n (%)]
Treatment methods and the results on histopathological diagnosis
Patients (n = 40)
EMR with mucosal incision
Depth of invasion
well differentiated adenocarcinoma (wel)
moderately differentiated adenocarcinoma (mod)
poorly differentiated adenocarcinoma (por)
Summary of results
Patients (n = 40)
Primary outcome measure
Usefulness rate % (n)
Complete en bloc resection
Additional counts of injection
Secondary outcome measures
Steepness of mucosal lesion-lifting % (n)
Intraoperative accidental events % (n)
Ease of mucosal resection % (n)
Time required for mucosal resection (min)
Injection volume (mL)
Usefulness rate for neoplasm size and location
All Patients (n = 41)
Patients with adverse events
Adverse events occurring in ≥ 2 patients†
Post procedural haemorrhage‡
Haemorrhage during procedure‡
Laboratory investigations and vital signs
Total protein, total bilirubin, and blood urea nitrogen levels did not significantly change between the time before endoscopic resection and 1 or 7 days after endoscopic resection using 0.4% SH. No abnormal changes in clinical laboratory findings were correlated with 0.4% SH. No abnormal changes in vital signs were seen in any of the patients.
At 8 weeks after endoscopic resection, residual neoplastic tissues or recurrent neoplasms were not evident in any of the patients. The rate of healing (complete loss of white patches at the site of resection at 8 weeks after endoscopic resection) associated with 0.4% SH was 100% (40/40).
Safety and usefulness
Usefulness (primary outcome measure) was assessed in terms of en bloc complete resection and requirement for 0–1 additional injection, and resection was considered safe if no adverse events were determined to be related to submucosal injections and no events led to notable disability or the requirement of additional treatment. Comprehensive assessment of usefulness and safety revealed that the usefulness rate with a 95% confidence interval for 0.4% SH was 82.5% (33/40; 67.2–92.7%).
In colorectal EMR, endoscopists have to acquire the skills of endoscopic technique, submucosal injection, and snaring because the large intestine has anatomical curves and many plicae. Endoscopists often could not adequately lift lesions and maintain those lifted lesions during conventional colorectal EMR using saline, which led to additional injections, failed snaring and/or perforation [19, 20]. Incomplete resection leads to residual or recurrent tumors. Complications of EMR such as bleeding and perforation often result in a longer hospital stay and increased hospital costs. Therefore, the mucosal lesion-lifting method allows easy removal of tumors during endoscopic resection, leads to en bloc resection, and decreases complications. Some experimental studies [19, 21] and case reports  have described the effectiveness of SH for EMR. SH is a macromolecular polysaccharide composed of D-glucuronate and N-acetyl-D-glucosamine; it is ubiquitous in human connective tissues and body fluids. SH is physicochemically very water retentive and viscoelastic, and is thus clinically used as a safe intraarticular injection preparation (ARTZ and ARTZ Dispo, Seikagaku, Tokyo, Japan) or as auxiliary compound in cataract surgery (OPEGAN 1.1 and OPEGAN Hi, Seikagaku). Because SH is highly viscoelastic even at concentrations of ≤ 1%, it does not increase osmotic pressure and it is not histotoxic [4, 19]. Hyun et al described that mucosal elevation lasted longer with 0.1% SH than with normal saline in their study using fresh mongrel transverse colon, and this seemed to be due to the viscosity of the SH solution . However, no multicenter studies have prospectively investigated the usefulness and safety of 0.4% SH as a submucosal injection solution in EMR for colorectal tumors.
We selected 0.4% SH in this study, because Onaya et al  reported that 0.4% SH created higher protrusion than physiological saline, 50% dextrose, hypertonic saline (3.7% NaCl), and glycerol. In addition, histological analysis showed no tissue injury caused by hypertonicity after 0.4% SH use . In this study, we allowed epinephrine and indigo carmine to be added to submucosal injection solutions. We did not investigate the potential effect of the volumes of indigo carmine and epinephrine because we used such small amounts of these solutions. Therefore, we believe that additional indigo carmine and epinephrine had an insignificant effect on the final concentration of SH.
The intention of calculating a sample size of 35 patients was to keep the length (precision) of the confidence interval to ± 10% from the success rate when the anticipated en bloc resection rate was assumed to be 90%. The en bloc resection rate for the current study was 92.5% (37/40), and this rate was consistent with our assumption (Figure 1). The en bloc complete resection rate was high (82.5%) in this study. In 33 (82.5%) patients, submucosal injection of 0.4% SH was judged to be useful. We had already reported a prospective multicenter randomized controlled study describing that the usefulness rate of 0.4% SH for treating gastric tumors was significantly higher for the 0.4% SH group (88.4%; 61/69) than for the control group (58.6%; 41/70) (p < 0.001) . The usefulness rate of this study of colorectal tumors was nearly as high as that of the gastric tumor study. Uraoka et al reported the en bloc complete resection rate of 62.0% using glycerol and 34.8% using saline for laterally spreading tumors with size less than 20 mm . In light of such reported findings, we believe that the complete en bloc resection rate of 82.5% found in this study is fairly good from a clinical point of view. Although the cost of 0.4% SH is higher than that of saline or glycerol, using 0.4% SH in colorectal endoscopic resection may lead to a higher en bloc complete resection rate. In cases of complete resection, patients are generally followed up on a yearly basis. In contrast, incomplete resection leads to residual or recurrent tumor and patients need follow-up endoscopy several times in a year. Thus, incomplete resection leads to increased medical expenses. Using SH in endoscopic resection can be expected to decrease medical expenses for patients and healthcare systems indirectly by potentially reducing the number of hospital visits and follow-up cost.
A steep lift was judged to be adequate in 75.0% of 40 patients in this study and 97.5% of 40 patients required no additional injections for endoscopic resection. No perforation occurred due to endoscopic resection in this study, although one perforation occurred during the management of bleeding. A solution of 0.4% SH, which is highly viscoelastic, provided sufficient formation and maintenance of lifted lesions, prevented perforation and facilitated safer and more complete procedures. These findings lead us to believe that 0.4% SH is useful for the resection of colorectal mucosal lesions.
Adverse events appeared to be at a relatively high rate (46.3%) in this study because we collected all minor adverse events in strict compliance with GCP. Major complications were bleeding during endoscopic resection (7.3% (3/41)) and postoperative bleeding (9.7% (4/41)) (Table 6). The adverse event rates in our study are only slightly higher than the adverse event rates reported by Uraoka et al  regarding the bleeding during endoscopic resection (0.9% for glycerol and 7.0% for saline) and the postoperative bleeding (6.4% for glycerol and 4.4% for saline). The slightly elevated bleeding rates in our study are thought to be unrelated to the use of SH and to be comparable to the bleeding rates reported in Uraoka et al.'s study using glycerol and saline . Nonetheless, it should be kept in mind that because unexpected bleeding may occur during colorectal endoscopic resection and such bleeding is very hard to predict in advance, one should pay careful attention to the possibility of bleeding during endoscopic resection using 0.4% SH as well as other injection solutions.
It must be noted that all procedures in this study were conducted by highly skilled endoscopists familiar with colorectal endoscopic resection whereas in other clinical settings, inexperienced endoscopists might perform colorectal endoscopic resections. Insufficient formation and the inability to maintain lifted lesions seemed to increase the difficulties associated with procedures. A solution of 0.4% SH could adequately lift and maintain lesions regardless of lesion location and the risk of perforation was reduced by creating sufficient space between the muscle layer and the mucosal lesion. In addition, due to its high molecular weight, 0.4% SH is sufficiently viscoelastic at low concentrations, does not affect osmotic pressure and is not associated with tissue damage. These properties may confer advantages as a local injection solution in colorectal endoscopic resection.
This study is a prospective open-label study. Although the study had only a single-arm, a modest sample size and some subjective measurements as potential limitations, the findings of the current study shed light on the usefulness of 0.4% SH as an aid for surgery when compared with available historical control data and reported findings from studies making use of other agents as surgical aids.
The outcomes in this study suggest that 0.4% SH, which can lift and maintain lesions during resection, can be applied to colorectal endoscopic resection for enhancing the ease and safety of the procedures. The potentially superior safety profile of 0.4% SH supports its use as a promising submucosal injection solution in place of conventional saline solution.
Good Clinical Practice
Endoscopic mucosal resection
Endoscopic submucosal dissection
Full analysis set
Institutional review boards
- IT knife:
Insulation-tipped electrosurgical knife
- ST hood:
Small-caliber tip transparent hood
This study was supported by Seikagaku Corporation (Tokyo, Japan).
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