Modified Kamikawa anastomosis after proximal gastrectomy: A narrative review

Abstract

The Kamikawa anastomosis, also known as the double-flap technique, is a digestive tract reconstruction method designed to reduce gastroesophageal reflux and anastomotic complications after proximal gastrectomy. However, its technical complexity has limited its widespread adoption. In recent years, the modified Kamikawa anastomosis (MKA) has been introduced to simplify key steps of the original procedure while preserving its anti-reflux mechanism. Major modifications include the use of barbed continuous suturing, individualized flap widths, improved esophageal mobilization, and ultrasonic opening of the esophageal stump. Available evidence suggests low rates of reflux esophagitis, anastomotic leakage, and stenosis in carefully selected patients; however, most data are derived from single-center retrospective series with limited follow-up. Multicenter prospective studies and randomized trials are still needed to define optimal indications, validate functional benefits, and clarify long-term oncological safety. This minireview summarizes the technical modifications, perioperative safety, functional preservation outcomes, and postoperative complication management of MKA after proximal gastrectomy, based on recent literature and clinical experience. The clinical value and future prospects of MKA are also discussed, with an emphasis on its potential role in improving postoperative recovery and quality of life.

Key Words: Modified Kamikawa anastomosis; Double-flap technique; Proximal gastrectomy; Gastroesophageal reflux; Digestive tract reconstruction; Function-preserving gastrectomy; Postoperative complication

Core Tip: Modified Kamikawa anastomosis is a simplified form of the Kamikawa double-flap technique for digestive tract reconstruction after proximal gastrectomy. By preserving the anti-reflux valve mechanism while reducing technical complexity, the modified Kamikawa anastomosis can reduce reflux and anastomotic complications and improve postoperative recovery. This minireview summarizes current technical refinements, clinical indications, perioperative safety, functional outcomes, and remaining evidence gaps, emphasizing the need for multicenter prospective studies and longer oncological follow-up.

INTRODUCTION

The incidence of tumors located at the esophagogastric junction (EGJ) and the upper-third of the stomach, particularly Siewert type II and III adenocarcinomas, has increased in many regions and continues to pose significant clinical challenges[1,2]. Total gastrectomy (TG) has traditionally been considered the standard radical treatment for proximal gastric cancer because it provides extensive resection and lymphadenectomy[3,4]. However, TG is associated with impaired digestion, nutritional deficiency, and compromised quality of life (QOL) due to the loss of gastric reservoir function[5,6]. According to the Japanese Gastric Cancer Treatment Guidelines 2021 (6^th edition), proximal gastrectomy (PG) is suitable for early-stage proximal gastric cancer, classified as cT1N0M0, and it may also be considered for selected adenocarcinomas of the EGJ[4]. With the increasing detection of early-stage proximal gastric and EGJ tumors, PG has been reappraised as a function-preserving gastrectomy that balances oncological radicality with functional preservation[7,8]. Compared with TG, PG better preserves nutritional parameters, including body weight, serum albumin, and hemoglobin levels, thereby contributing to improved long-term recovery[9-11].

A major limitation of PG is the high incidence of postoperative gastroesophageal reflux (GER) disease, including reflux esophagitis, which results from the resection of the cardia and the lower esophageal sphincter and compromises postoperative QOL[7]. Several reconstructive techniques have been developed to reduce reflux after PG, including double-tract reconstruction (DTR), jejunal interposition, jejunal pouch interposition, side overlap fundoplication (SOFY), and the Kamikawa double-flap reconstruction[12-16]. The Kamikawa double-flap technique creates a valve-like mechanism using seromuscular flaps from the remnant stomach. Although effective, the original Kamikawa technique is technically demanding and time-consuming and thus not widely adopted[17,18]. The modified Kamikawa anastomosis (MKA) has been developed to simplify reconstruction while maintaining anti-reflux efficacy and anastomotic safety[11,18-20]. This minireview summarizes the technical progress, patient selection, perioperative safety, clinical outcomes, limitations, and future research priorities of MKA after PG.

METHODS: LITERATURE SEARCH AND SELECTION CRITERIA

This article was prepared as a narrative minireview. A literature search was conducted in PubMed to identify studies published up to January 2026 that addressed PG, Kamikawa anastomosis, the double-flap technique, MKA, reflux prevention, anastomotic leakage (AL), anastomotic stenosis (AS), nutritional outcomes, QOL, robotic surgery, and EGJ cancer. Representative search terms included “proximal gastrectomy”, “Kamikawa anastomosis”, “double-flap technique”, “modified Kamikawa anastomosis”, “anti-reflux reconstruction”, “gastroesophageal reflux”, “anastomotic leakage”, “anastomotic stenosis”, and “quality of life”. Original clinical studies, systematic reviews, meta-analyses, multicenter retrospective studies, technical reports, and relevant guidelines were prioritized. Studies were selected according to their relevance to surgical techniques, perioperative safety, postoperative reflux, nutritional or quality-of-life outcomes, and oncological considerations. Articles not focused on PG reconstruction or not directly related to the Kamikawa or the double-flap technique were excluded. Because the available evidence was derived mainly from retrospective and single-center studies, the findings are summarized descriptively rather than through a formal quantitative meta-analysis.

SURGICAL TECHNICAL FEATURES OF THE MKA

Anatomical basis and design concept of the double-flap technique

The double-flap technique, also known as the Kamikawa anastomosis, was originally reported by Kamikawa[21] as a valvuloplastic esophagogastrostomy procedure after PG in 2001. Its anatomical basis and design concept hinge on the strategic use of the anatomical layers of the gastric wall to create two symmetrical seromuscular flaps that act as a valve by enveloping the esophageal stump in the submuscular tunnel, thus effectively constructing an anti-reflux mechanism to replace the function of the pylorus. Briefly, two seromuscular flaps are fashioned in a horizontal H shape by dissecting the space between the submucosa and muscularis propria along a longitudinal incision on the anterior wall of the residual stomach after esophagogastrostomy. The gastric remnant opening is located at the inferior edge of the ‘mucosal window’ beneath the flaps for anastomosis with the esophageal stump. Subsequently, the flaps are folded over the esophagus and sutured to cover the anastomotic site and distal esophagus, creating a large pseudo-fornix and an ideal shape for the EGJ that mimics the gastric cardia to achieve an anti-reflux effect. This muscle coverage also helps reduce the tension exerted on the anastomotic site, thereby lowering the risk of AL and AS.

Multiple clinical studies have demonstrated the safety and feasibility of the double-flap technique, including its laparoscopic application, with low rates of AL, AS, and postoperative reflux[22]. For example, laparoscopic double-flap reconstruction has been successfully performed in patients with EGJ tumors > 5 cm, with no reflux symptoms observed during follow-up[23]. However, the original Kamikawa anastomosis (OKA) is technically challenging and time-consuming, requiring meticulous dissection and interrupted suturing between multiple layers within a confined operative space, which limits its widespread adoption[24].

Detailed surgical steps of the MKA

With the growing use of function-preserving gastrectomy and advances in minimally invasive surgical instruments, the MKA technique was developed and subsequently adopted by many institutions in China. The basic steps of laparoscopic PG with MKA for early-stage proximal gastric cancer (cT1N0M0) are as follows.

The patient is in the supine split-leg position, with the head side slightly higher than the feet. The surgeon usually stands on the patient’s left side, with surgical assistants standing on the patient’s right side, and a laparoscopy handler stands between the patient’s legs. A five-port technique is used: One port through which a 12 mm trocar is inserted below the umbilicus serves as the observation port; the other four operative ports are located 2 cm below the costal margin along the left and right anterior axillary lines and 2 cm above the umbilicus along the left and right mid-clavicular lines, respectively. The upper left port is the main operative port, with a 12 mm trocar inserted, and the other three are auxiliary ports, each with a 5 mm trocar inserted. Once the pneumoperitoneum is established with intra-abdominal pressure maintained at 12-15 mmHg (note: 1 mmHg = 0.133 kPa), the laparoscope is used to check the location and size of the tumor, the depth of invasion, and the presence of metastasis. Intraperitoneal lavage for cytological examination of malignant cells is performed separately in the left subphrenic area and the pelvic cavity. In accordance with the Japanese Gastric Cancer Treatment Guidelines 2021 (6^th edition), D1+ lymph node dissection is performed followed by laparoscopic PG[4]. The esophageal hiatus is opened, and the right side of the diaphragmatic sac serves as a landmark to expose both pleurae (Figure 1A-C). The mesoesophagus is dissected to fully mobilize the lower esophagus (Figure 1D). Intraoperative gastroscopy is performed to locate the EGJ and to check the preoperatively placed marking clips for proper resection margins. The esophageal resection line is marked either above the EGJ for tumors without esophageal invasion or 2 cm above the upper edge of tumors with esophageal invasion. The gastric resection line is marked at 3-5 cm distal to the lower edge of the tumor. Linear cutting staplers are used to resect the specimen along the resection lines. A small subxiphoid incision is made to remove the tumor specimen, and resection edges are sent for rapid frozen-section examination to ensure an R0 resection.

Figure 1 Main procedural steps of modified Kamikawa anastomosis after proximal gastrectomy. A-C: Exposure of the esophageal hiatus and the right diaphragmatic sac to expose both pleurae; D: Dissection of mesoesophagus and mobilization of the lower esophagus; E: Horizontal H-shaped marking on the anterior wall of the gastric remnant using gentian violet; F: Dissection between the submucosa and muscularis layers to create double seromuscular flaps; G: Creation of a gastric opening along the inferior edge of the ‘mucosal window’; H: Fixation of the posterior esophageal wall to the gastric remnant; I: Continuous suturing of the posterior wall of the esophageal opening and the upper lip of gastric opening; J: Continuous suturing of the anterior wall of the esophageal opening and the lower lip of gastric opening; K and L: Continuous suturing of the inferior flap edges and the adjacent gastric wall from each side to the midpoint, followed by continuous suturing upward and obliquely toward each side to fix the bilateral flaps together to the esophageal adventitia; M: Formation of a Y-shaped collar-like structure covering the anastomosis and lower esophageal segment.

MKA is performed as follows. The gastric remnant is extracted through the incision. A horizontal H-shaped mark, measuring 2.5-3.0 cm × 3.5 cm (width × length) is applied to the anterior wall of the gastric remnant using gentian violet (Figure 1E). This mark is placed parallel to and approximately 1.5 cm from the cutting line, with its precise width matching the diameter of the esophagus. The submucosal layer is then incised along the mark using electric cautery. While vertical tension is applied to the muscularis layers, dissection is performed between the submucosa and muscularis layers to create double seromuscular flaps. Integrity is maintained for both the flaps and the exposed gastric ‘mucosal window’ beneath them (Figure 1F). Any point of bleeding is electrocoagulated using electric cautery.

Once the double flaps are in their appropriate shapes, a gastric opening is made along the inferior edge of the ‘mucosal window’ for subsequent anastomosis (Figure 1G). The gastric remnant is then returned to the abdominal cavity, followed by the reinflation of the peritoneum. Next, the esophagus is pulled caudally and marked with gentian violet on its posterior wall at 5 cm above the cut end, where the esophageal posterior wall is fixed to the gastric wall along the superior edge of the ‘mucosal window’ with a four-stitch continuous barbed suture under laparoscopy (Figure 1H). The cut end of the esophageal stump is then opened with an ultrasonic scalpel for anastomosis.

Two barbed sutures are used for the anastomosis of the posterior and anterior walls of the esophageal opening with the gastric opening. The first barbed suture is used to suture the entire layers of the posterior wall of esophagus with the upper lip of the gastric opening continuously from the left to the right apex. The suture needle reserved at the inferior right corner of the right flap by entering it into the mucosal layer and having it exit the serosal layer of the gastric wall for later use (Figure 1I). The second barbed suture is applied to suture the entire layers of the anterior wall of the esophagus and the entire gastric layers of the lower lip continuously from the right to the left apex, with the suture needle reserved at the inferior left corner of the left flap (Figure 1J).

Subsequently, the lower ends of the bilateral seromuscular flaps are crossed and fixed to the gastric wall below the midpoint of the anastomosis. The reserved barbed sutures are used respectively to suture the inferior edge of each flap and adjacent gastric wall continuously from each corner to the crossing point, followed by a continuous suture of 3 to 4 stitches along the midline upward to fix the bilateral flaps together to the esophageal adventitia (Figure 1K). The suture then extends obliquely toward each side respectively (Figure 1L), ultimately forming a Y-shaped collar-like structure fully covering the anastomosis and lower esophageal segment (Figure 1M). Finally, the blood supply of the seromuscular flap is observed, and the anastomosis is examined intraluminally via a gastroscope to exclude potential AS. After irrigation and hemostasis are performed under laparoscopy, a drainage tube is placed on the dorsal side of the anastomosis, and the incisions are sutured to complete the procedure.

Key modification points

The basic modifications to the Kamikawa anastomosis adopted across multiple centers can be summarized as follows: (1) Replacement of interrupted sutures with barbed continuous sutures for the esophagogastric anastomosis and fixation of the posterior esophageal wall to the gastric remnant, thereby reducing repetitive knot tying and improving laparoscopic efficiency; (2) Adjustment of the width of the horizontal H-shaped seromuscular flaps, usually to 2.5-3.0 cm, according to the esophageal diameter to reduce the risk of postoperative AS; (3) Improved mobilization of the lower esophagus based on the concept of total mesoesophageal resection around the lower esophagus and EGJ, which facilitates lower mediastinal paraesophageal lymph node dissection and provides a tension-free esophageal stump for anastomosis; and (4) Use of an ultrasonic scalpel to open the esophageal stump, which reduces bleeding; maintains close apposition of the esophageal mucosa, muscular layer, and adventitia; and helps prevent mucosal retraction.

Other technical refinements have also been reported. Wu et al[19] expanded the operative space by mobilizing and flipping the left lateral liver lobe without causing liver trauma. They also positioned the double flaps closer to the lesser curvature to improve flap perfusion and support anti-reflux function. Another modification involves placing two preliminary stitches to approximate the posterior wall of the esophageal opening and the upper lip of the gastric opening at the right apex and midpoint, respectively, which facilitates subsequent continuous suturing and may be particularly useful for less experienced surgeons[11]. Together, these modifications are intended to simplify the original Kamikawa procedure while maintaining its safety, feasibility, and anti-reflux efficacy compared with other reconstructive techniques[11,20].

CLINICAL INDICATIONS AND CASE SELECTION FOR PG WITH MKA

According to the Japanese Gastric Cancer Treatment Guidelines 2021 (6^th edition), early-stage proximal gastric cancer (cT1N0M0) is suitable for PG with D1/D1+ lymphadenectomy, and PG is also considered when the tumor center is located within 2 cm of the EGJ[4]. PG is also a suitable surgical option for benign or low-grade malignant gastric diseases, such as gastrointestinal stromal tumors that are close to the EGJ with the distal gastric body remaining healthy[25]. The primary surgical goal in these cases is the complete excision of the lesion while preserving as much normal gastric volume and function as possible to achieve a favorable balance between oncological radicality and postoperative QOL. The indications for Kamikawa anastomosis are thus tightly linked to early-stage tumors confined to the upper-third stomach and the EGJ without nodal involvement, requiring thorough preoperative assessment of the cTNM stage, tumor location, and size using contrast-enhanced computed tomography and endoscopic ultrasonography.

Additional considerations involve the extent of resection and the volume of the gastric remnant. Despite the considerable mobility of the stomach, MKA still requires a sufficient volume of the gastric remnant for the anastomosis, with usually at least half of the stomach preserved. Moreover, certain intraoperative conditions must be met to ensure the successful completion of the Kamikawa anastomosis: (1) R0 resection must be ensured based on intraoperative frozen section pathological examination of the surgical margins; (2) The esophageal stump and the remnant stomach must be able to overlap by > 5 cm without tension for the consequent anastomosis; and (3) The anticipated anti-reflux effect should also be considered when identifying appropriate surgical candidates, especially for patients with tumors that invade higher positions of the esophagus, because an anastomosis located in the mediastinum or thoracic cavity may increase the risk of reflux esophagitis[26]. Published studies on MKA demonstrating excellent postoperative anti-reflux outcomes have included only patients without esophageal invasion[11,19,20]. However, based on experience from our center, MKA can still be considered for patients with esophageal invasion of the tumor within 1 cm, and satisfactory anti-reflux outcomes can still be achieved in such cases[18]. Careful preoperative staging and a thorough assessment of tumor characteristics are thus essential for selecting patients who can safely undergo PG with MKA. Nevertheless, a greater accumulation of clinical data is necessary regarding surgical candidate selection, particularly for patients with greater esophageal invasion.

The statement that MKA may be considered for tumors with esophageal invasion within 1 cm is based on limited center experience and should be applied cautiously until larger studies clarify the safety and anti-reflux efficacy of MKA in this subgroup.

PERIOPERATIVE SAFETY AND COMPLICATION MANAGEMENT

Intraoperative bleeding and operative time control

Effective control of intraoperative bleeding and optimization of operative duration are critical factors influencing safety and recovery after PG. The MKA technique incorporates several innovations aimed at minimizing blood loss and streamlining the OKA procedure. For instance, the use of an ultrasonic scalpel for esophageal stump incision not only reduces bleeding by coagulating the mucosal and muscular layers together but also prevents mucosal retraction, thereby facilitating precise suturing and reducing operative complexity. The use of continuous rather than intermittent suturing also simplifies the process and reduces the time required for anastomosis.

In the study by Wu et al[11], the median intraoperative blood loss in patients undergoing MKA was 22.0 mL (interquartile range, 16.0-27.0 mL). This value appeared lower than the median blood loss reported in several studies of OKA, which ranged from 31 mL to 240 mL[26-28]; however, this is an indirect comparison across different studies and should be interpreted cautiously. There was no significant difference in intraoperative blood loss when comparing MKA with other anastomotic methods such as DTR and Roux-en-Y[11,20].

The median operative time and digestive tract reconstruction time for MKA were 203.5 (150-224) minutes and 87.5 (73-111) minutes, respectively, which were shorter than the 388.5 (230-780) minutes and 120 (60-312) minutes for OKA, even when performed by an experienced team[11,29]. Although MKA reduces operative time by approximately half compared with OKA, it is still slower than the DTR method due to its complexity[20]. Furthermore, although the reconstructive time for MKA was longer than that for Roux-en-Y anastomosis, there was no significant difference in total operative time, indicating that MKA did not prolong the surgical duration compared with traditional laparoscopic TG[11]. Moreover, concerning patients’ postoperative recovery, the longer operative time associated with MKA did not adversely affect the postoperative hospital stay or complication rates compared with DTR and Roux-en-Y, underscoring the safety of MKA. In summary, a reduction in intraoperative bleeding and operative time is achieved through the use of advanced surgical tools such as ultrasonic scalpels, barbed sutures, and modified suturing strategies in MKA compared with OKA (Table 1).

Table 1 Summary of surgical outcomes reported for Kamikawa and modified Kamikawa anastomosis after proximal gastrectomy.

Ref.	Study design	Operative time (minute)	Digestive tract reconstruction time (minute)	Blood loss (milliliters)	Anastomotic leakage	Anastomotic stenosis
Liu et al[17]	Systematic review/meta-analysis of Kamikawa anastomosis	317.8 (95%CI: 274.1-361.4; I2 = 99.4%)	93.1 (95%CI: 83.7-102.4; I2 = 69.8%)	55.9 (95%CI: 43.9-67.9; I2 = 99.3%)	1.8%	7.2%
Kuroda et al[26]	Multicenter retrospective study: Double-flap technique study	298 (247.5-370.5)	Not reported	240 (100-392.5)	1.5%	5.5%
Wu et al[19]	Retrospective case series: Laparoscopic proximal gastrectomy with MKA	203.5 (150-224)	87.5 (73-111)	20.5 ± 0.7	None	None
Wu et al[11]	Retrospective cohort study: MKA vs TG with Roux-en-Y reconstruction	195.9 ± 25.0 vs 228.3 ± 59.8	93.0 (74.0-111.0) vs 39.7 (35.1-46.2)	22.0 (16.0-27.0) vs 23.0 (11.0-48.0)	Both none	One case vs none
Wu et al[20]	Retrospective analysis: MKA vs DTR	210.0 (150.0-240.0) vs 186.5 (167.0-226.0)	89.0 (78.0-116.0) vs 80.0 (73.0-97.0)	21.0 ± 3.8 vs 22.9 ± 4.7	Both none	Both none
Hu et al[29]	Retrospective analysis: Robotic vs laparoscopic double-flap technique	457 (270-751) vs 394 (266-780)	Not reported	45 (0-520) vs 70 (10-780)	0% vs 2.8%	26.6% vs 11.9%
Muraoka et al[22]	Retrospective case series: Laparoscopic proximal gastrectomy with Kamikawa anastomosis	356 (279-480)	Not reported	30 (1-850)	4.2%	8.3%
Kano et al[27]	Retrospective analysis: Laparoscopic PG with DFT vs laparoscopic subtotal gastrectomy	404 (339-446) vs 289 (233-325)	Not reported	68 (29-120) vs 30 (20-70)	Both none	8% vs 2.7%
Shibasaki et al[28]	Single-arm retrospective cohort study: Robotic DFT	406 (324-613)	104 (76-186)	31 (5-130)	None	25%

CI: Confidence interval; MKA: Modified Kamikawa anastomosis; TG: Total gastrectomy; DTR: Double-tract reconstruction; PG: Proximal gastrectomy; DFT: Double-flap technique.

AL, stenosis, and their prevention

AL remains a critical postoperative complication with significant morbidity and mortality after PG, but AL is reported to be uncommon after Kamikawa anastomosis due to reinforcement of the anastomosis by the seromuscular double-flap. A recent meta-analysis indicated an AL incidence of approximately 1.8% after OKA, and a multicenter retrospective study reported a rate of 1.5%[17,26]. Clinical experience with MKA after PG has also demonstrated a favorable safety profile with low AL rates (approximately 1.8%-4%), which are relatively lower than those observed with DTR and Roux-en-Y reconstruction[19,20].

AS is a postoperative complication that requires careful attention in the Kamikawa reconstruction procedure. A multicenter retrospective study reported that AS requiring endoscopic balloon dilatation was the most frequent anastomosis-related complication, occurring in 5.5% of 546 patients, with laparoscopic reconstruction identified as an independent risk factor[26]. In another study of 147 patients undergoing laparoscopic PG with Kamikawa anastomosis, AS requiring endoscopic balloon dilatation occurred in 8.3% of patients, and multivariate analysis identified an esophageal diameter < 18 mm on a preoperative computed tomography image and the presence of short-term complications as independent risk factors for AS[30].

The risk of AS following Kamikawa anastomosis can be reduced by paying close attention to key aspects of the suturing technique applied in MKA. First, adjusting the width of the seromuscular double-flap to 2.5-3 cm, corresponding to the esophageal diameter, ensures appropriate matching between the esophagus and the gastric mucosal opening, thereby facilitating even tension during the anastomosis and preventing excessive tightness of the reinforcing flaps. Second, when suturing the double flaps to the esophageal wall, careful control of suture tension is required, along with timely adjustment of suture placement to avoid excessive tightening. Third, intraoperative gastroscopy can help reduce AS by allowing real-time assessment of the anastomosis and preventing overly tight flap closure, as reported by Muraoka et al[22]. In the retrospective study by Wu et al[19], no AS was observed in patients undergoing MKA. An analysis comparing the short-term clinical efficacy of MKA and DTR after PG showed that the MKA group experienced no anastomotic complications and a significantly shorter time to first postoperative fluid intake, drainage tube removal, and postoperative hospital stay[20]. Additionally, MKA offers advantages in preserving anatomical continuity and facilitating postoperative endoscopic surveillance. Overall, available clinical data support the safety and feasibility of MKA, with effective management of anastomotic complications (Table 1).

POSTOPERATIVE FOLLOW-UP AND LONG-TERM OUTCOME OBSERVATIONS

Evaluation and prevention of postoperative GER

Postoperative GER remains an important concern after PG, as it may lead to reflux esophagitis and substantially compromise long-term QOL. Affected patients may experience persistent symptoms, including regurgitation, heartburn, and cough, which can be assessed using GER disease symptom scales. Effective evaluation and prevention strategies are therefore essential to improve postoperative outcomes. The Los Angeles (LA) classification is widely recognized as a standardized and objective method for grading reflux esophagitis during postoperative endoscopic evaluation, classifying severity from A to D based on the extent and continuity of mucosal breaks. Multiple studies have applied the LA classification to stratify GER severity after PG with various reconstructive procedures, including Kamikawa anastomosis. Simple esophagogastrostomy without an additional anti-reflux measure has been reported to cause reflux esophagitis in 9.1%-35.3% of patients, and the reported incidences of postoperative reflux esophagitis after different anti-reflux measures were as follows: SOFY (7.1%-17.8%), jejunal interposition (0%-33.3%), jejunal pouch interposition (4%-27.8%), and DTR (0%-25%)[31-33]. A systematic review and meta-analysis including 2291 patients confirmed that the Kamikawa anastomosis was successful in preventing reflux esophagitis (LA grade B or higher) with a pooled incidence of 4.9%[17]. In a multicenter analysis of 464 patients, Kuroda et al[26] reported a “real-world” incidence of reflux esophagitis of 10.6% for all grades and 6.0% for grade B or higher after Kamikawa anastomosis. A retrospective study of 25 patients undergoing MKA reported an exceptionally low rate of reflux symptoms and esophagitis, with most patients showing no or only mild LA grade A esophagitis postoperatively[17]. Another study with a 12-month follow-up of 26 patients found no reflux esophagitis after laparoscopic PG with MKA, along with favorable nutritional status and recovery[19]. These findings underscore the clinical efficacy of MKA in mitigating GER after PG.

Postoperative nutritional status and QOL assessments

Postoperative nutritional status and QOL are critical parameters for evaluating the efficacy of reconstructive methods following PG aimed at functional preservation. Several studies have demonstrated that patients undergoing PG with MKA achieve more favorable outcomes in terms of weight maintenance and nutritional absorption compared with other reconstruction techniques. In a retrospective cohort study comparing laparoscopic PG with MKA vs laparoscopic TG with Roux-en-Y reconstruction, patients in the MKA group showed significantly better body mass index (BMI) and Nutritional Risk Screening 2002 scores at 6 months and 12 months after surgery, suggesting more favorable nutritional recovery. Specifically, BMI values were 22.9 ± 3.0 kg/m² vs 20.8 ± 2.2 kg/m² at 6 months and 23.1 ± 3.0 kg/m² vs 20.3 ± 2.2 kg/m² at 12 months for the MKA vs Roux-en-Y groups, respectively[11]. Regarding patient-reported outcomes, a comparative study of MKA and DTR after laparoscopic PG using the Postgastrectomy Syndrome Assessment Scale-45 found that patients who underwent MKA generally reported fewer reflux symptoms and better overall postoperative QOL. Although postoperative nutritional parameters, including hemoglobin, serum albumin, BMI, and nutritional risk scores, were not significantly different between the groups at 6 months and 12 months, the MKA group showed higher QOL scores at 12 months compared with the DTR group, suggesting potential advantages in postoperative patient-centered outcomes[20]. These findings suggest that MKA may contribute to better long-term nutritional status and patient satisfaction.

Postoperative recurrence and survival data

Tumor recurrence is a key determinant of long-term outcomes after any surgical treatment. The risk of recurrence after PG with MKA is influenced by multiple factors, including tumor stage, lymph node involvement, surgical margin status, and the adequacy of lymphadenectomy, particularly around the EGJ and lower mediastinum. Therefore, MKA should not be interpreted as a substitute for adequate oncological resection or lymph node dissection. It is performed after the oncological resection has been completed and is intended to improve the reconstruction-related functional outcomes. Conversely, MKA may facilitate lower mediastinal lymph node dissection through total mesoesophageal resection around the lower esophagus and EGJ. Theoretically, with careful selection of early-stage tumors and adequate lymph node dissection, MKA does not compromise oncological clearance. In the included studies with a follow-up of up to 12 months, postoperative recurrence was not reported[11,19,20]. However, these data are insufficient to establish long-term oncological safety. Longer follow-up, standardized reporting of recurrence patterns, and prospective comparisons with other reconstruction methods are needed before firm conclusions can be drawn regarding survival outcomes after PG with MKA.

KAMIKAWA ANASTOMOSIS: FUTURE DEVELOPMENT TRENDS AND CLINICAL PROMOTION CHALLENGES

Surgical techniques and auxiliary device innovations

Robotic surgery for PG offers a promising alternative to laparoscopy, providing the dexterity, tremor control, and 3D visualization needed for precise suturing and dissection in confined spaces. A recent study suggested that the robotic approach may reduce intraoperative blood loss and anastomotic time for Kamikawa anastomosis while achieving short-term outcomes and anti-reflux effects comparable to those of the laparoscopic approach[29]. However, a higher incidence of AS has been reported with the robotic approach during the introductory phase, possibly because the lack of tactile feedback in the da Vinci system may lead to excessive suture tightness. The current evidence for robotic-assisted MKA remains limited and should be interpreted cautiously. Therefore, robotic-assisted PG with MKA should currently be considered mainly in experienced centers and requires further validation in larger prospective studies.

Most studies of MKA following laparoscopic PG have focused on gastric tumors without esophageal invasion[11,19,20]. Its anti-reflux efficacy in the mediastinal or thoracic anastomoses remains unclear. A multicenter retrospective study identified an anastomotic site located in the mediastinum or thoracic cavity as an independent risk factor for reflux esophagitis after Kamikawa anastomosis, likely due to negative intrathoracic pressure[26]. Matsuo et al[34] further reported that a resected esophageal length > 20 mm was a significant risk factor for reflux esophagitis. Video-based analysis suggested that when an anastomosis is performed in the narrow mediastinal space without adequate insertion of the gastric remnant, formation of the pseudo-fornix and the angle of His may be incomplete, resulting in suboptimal intragastric pressure and reduced anti-reflux function[34]. In contrast, Mine et al[35] demonstrated that satisfactory anti-reflux outcomes can be achieved even in intrathoracic esophagogastrostomy using the Kamikawa technique applied to a gastric tube. Future studies are needed to evaluate the feasibility and efficacy of MKA in mediastinal and intrathoracic settings, as well as in tubular stomach reconstruction for tumors with greater esophageal involvement.

Training system and surgical team building for the MKA

Although several modifications have simplified the complex suturing procedures of the OKA, MKA reconstruction still relies on meticulous hand-sewn techniques that require advanced surgical skills and a coordinated team effort to minimize complications. Several studies have identified the learning curve as an important factor influencing the incidence of anastomotic complications after Kamikawa anastomosis, whether performed laparoscopically or robotically, underscoring the need for adequate training to optimize efficiency without compromising safety[17,26,29]. In this context, surgeons should undergo systematic training that integrates theoretical knowledge with practical skills, along with rigorous supervision and assessment by experienced surgeons before independent practice. Continuous education and peer review are also essential to maintain high standards and incorporate ongoing technical refinements. Beyond individual training, a multidisciplinary team - including surgeons, anesthesiologists, radiologists, nutritionists, and nursing staff - facilitates collaborative decision-making and tailored patient management, which are crucial for optimizing perioperative care and outcomes in patients undergoing MKA.

Clinical research and evidence-based medicine support

Although the clinical application and validation of MKA have attracted increasing attention, existing studies are predominantly single-center, retrospective, small-scale, and non-randomized designs, which may introduce selection bias. Patient populations are also heterogeneous with respect to tumor location, tumor stage, esophageal invasion, remnant stomach size, surgical approach, surgeons’ experience, and follow-up duration. These differences limit direct comparison among MKA, OKA, DTR, SOFY, and Roux-en-Y reconstruction. In addition, long-term oncological data remain limited, and the efficacy of MKA in patients with esophageal invasion or intrathoracic anastomosis remains uncertain. Therefore, rigorous multicenter prospective studies and, where feasible, randomized controlled trials are needed to confirm the long-term safety, functional benefits, oncological adequacy, and appropriate selection criteria for MKA, particularly in patients with EGJ tumors.

CONCLUSION

The MKA technique has shown considerable promise as an effective reconstructive option after PG, combining a strong anti-reflux mechanism with low anastomotic complication rates and favorable postoperative QOL in carefully selected patients. Technical modifications to the original Kamikawa procedure have simplified the operation and improved its feasibility without compromising its intended functional benefits. However, current evidence remains limited due to retrospective study designs, small sample sizes, heterogeneity in patient selection, and short follow-up periods. High-quality multicenter prospective studies are necessary to better define patient selection criteria, validate functional benefits, and confirm long-term oncological safety. Continued technical refinement, standardized training, and stronger clinical evidence may further support the broader application of MKA in function-preserving surgery for proximal gastric and EGJ tumors.