Current laser application in En bloc resection of bladder tumor- a narrative literature review

Abstract

At present, laser en bloc resection of bladder tumor (ERBT) has attracted great interest with potential superiority to transurethral resection of bladder tumor (TURBT). It has several advantages, including complete resection, intact specimen for accurate histologic assessment, avoiding fragmentation and tumor seeding, preventing obturator nerve reflex, and reduction of inflammatory response. Several types of lasers have been studied in the application of ERBT, for example, holmium laser, green-light laser, thulium laser, diode laser. This paper reviews current literature concerning the characteristics of these types of laser, the surgical technique and procedures of laser ERBT with its advantages and limitations, and future directions in clinical development, aiming to display the status quo of these techniques in clinical practice.

Background

Cancer control is the most critical purpose in the treatment of malignancies. For non-muscle invasive bladder cancer (NMIBC) patients, transurethral resection of bladder tumor (TURBT) removes the lesion by endoscopic technique, which not only achieves local control of the tumor, but also maximizes the preservation of bladder function. As the classic technique for diagnosis and treatment of NMIBC [1], the main goals of TURBT include: ⑴ to resect completely and accurately all visible tumors, ⑵ to provide complete specimens for histopathology evaluation- staging and grading of bladder cancer (BC), and ⑶ to guide the subsequent follow-up protocols and determine prognostic factors. Technically, the standard TURBT involves piecemeal resection of the tumor, including the exophytic part and the underlying bladder wall with detrusor muscle (DM). However, this procedure destroys the integrity of the tumor and violates the established oncological principles, leading to a potentially elevated risk of tumor recurrence [2].

During TURBT, the tumor is cut in an “incise and scatter” manner, so there exists risks such as excessive bleeding, unclear vision and accidental injury to the surrounding bladder wall. Inadequate tumor clearance results in not only cancer recurrence, but also mis-staging or mis-grading. For example, incomplete specimen without DM or thermal injury to basal tissues could lead to insufficient evaluation of muscle invasion and incorrect guidance of subsequent management [3]. Absence of DM in the gross samples was reported to be as high as 40% after TURBT [4]. More importantly, the piecemeal resection could result in intravesical implantation, and large number of exfoliated cells could lead to distal metastases due to diffusion through the bloodstream [5, 6]. These consequences place a substantial burden on both patients and the society.

Except for the poor quality of specimens, many complications could occur after TURBT. The relatively shallow resection needs to be compensated by a secondary surgery: re-TURBT. The electrical cauterization of resection loop could destroy the margin or base of the specimens and form eschar [7]; thus, the accuracy of the pathologic evaluation was negatively affected [4]. It has been revealed that thermal injury- a temperature that ranged between 100 °C and 300 °C generated by the electrical current- is yielded in the treatment area; and the high temperature and extensive cautery ruin tumor cells and morphology of the specimens [8]. During piecemeal resection, the depth and margins of tumor invasion are determined mainly by surgeon’s clinical experiences and indirect visual feedback, but this is very subjective, making it difficult for surgeon to balance the safety and efficacy of TURBT. Furthermore, when resecting lateral wall tumors, obturator nerve reflex (ONR) might occur, and bladder perforation or even conversion to open surgery could ensue [9].

In addition, TURBT is not very suitable for patients with pacemakers or taking anticoagulant. Because the electrical current could potentially interfere with the function of pacemaker, causing it to temporarily dysfunction or trigger incorrectly. For patients taking anticoagulants, the risks of intra-operative or post-operative bleeding or thromboembolism might increase, especially for elderly patients [10].

BC has been one of the most expensive cancers in modern era, thus researchers are seeking better methods to make up for these drawbacks, trying to improve treatment strategies and reduce medical concerns [11]. A novel technique- en bloc resection of bladder tumor (ERBT)- is gradually entering the field of urology, with its major advantages of preserving tumor specimen architecture, facilitating better pathological assessment, and offering improved safety profile. Herein, we discussed laser ERBT- a more recently developed and popularized surgical procedure in the management of NMIBC [12].

Since the first application of neodymium (Nd): yttrium aluminum-garnet (YAG) laser in 1978¹³, laser therapy has been widely used in multiple urologic disorders, for example, urinary calculus, benign prostatic hyperplasia (BPH), strictures and urothelial cancers. The “en bloc resection” technique means removal of the tumor in its entirety, encompassing tumor and its base with a safety margin (“a no-touch technique”); and the resection is deep enough to remove the underneath DM [14], conforming to the oncological criteria of “optimized resection with low residual tumor rates” for cancer treatment [15]. Clinically, ERBT could be performed using monopolar or bipolar current, or various kinds of lasers. However, monopolar or bipolar current can also cause ONR when resecting tumor located at the lateral wall, thus the advantages are limited. In recent years, the clinicians’ interest in laser ERBT has increased due to the prominent characteristics of lasers, such as fewer complications, faster recovery, as well as less risk of tumor recurrence [9].

Methodology

The research was performed by use of internet searching engines, with thorough literary and information research being conducted. Articles retrieved after a search conducted in the national and international database were included in the research. The search was carried out using a variety of keywords such as “laser resection”, “transurethral resection of bladder tumor”, “en bloc resection”, “bladder cancer”, “types of laser” and so on. Initial 215 records were filtered by title/abstract, excluding non-English studies and those focusing on comorbidities. Full texts of 76 articles were assessed and studied.

Laser ERBT technology in bladder tumor resection

Laser is an acronym for “light amplification by stimulated emission of radiation”, referring to a kind of high intensity, mono-chromatic, coherent and highly focused light beam produced by stimulated radiation. Lasers have multiple tissue effects: absorption, scattering, transmission, reflection, as well as good tissue penetration capability [16]. One of its important advantages is transmitting through thin and flexible fibers, so it can be applied with endoscopy or in narrow area [17]. When laser is used for ERBT, the general principles are: specific wavelength of laser is absorbed by soft tissues, subsequently converting into thermal energy; once the temperature rises above the boiling point of the tissue, it can cause direct vaporization, producing “cutting” effects; meanwhile, denaturation of proteins in the surrounding tissue generates “coagulation” effect. Therefore, when performing lasers ERBT, it is particularly important to understand the characteristics of lasers: the wavelength, absorption efficiency, and the penetration depth.

The first clinical application was Nd: YAG laser [18]. However, several significant shortcomings led to the abolishment of this laser in BC, because its deep tissue penetration of about 4–18 mm can cause accidental bowel injury, particularly on the posterior and dome of the bladder [19]. As the laser technology develops, several types of lasers have been used in ERBT. We describe the commonly used lasers in ERBT, and a brief overview of clinical studies investigating laser ERBT is seen in Table 1.

Table 1 A brief overview of clinical studies investigating laser ERBT

Holmium laser

Holmium laser was used for BC in the mid-1990s, and holmium ERBT was first performed in 2001 [24]. Its wavelength is 2100 nm and tissue penetration depth is about 400µm [8]. In water, holmium laser has high absorption coefficient, thus causing minimal thermal injury to the surrounding tissues. It has good vaporization, cutting and coagulation hemostatic powers, producing no obvious carbonization, so a very clear tissue layer can be observed during surgery. Theoretically, it is possible to precisely cut tumor tissues and avoid residue. Thus, serious complications- such as bladder perforation- might be prevented. Clinical observations showed that postoperative wound healing is fast and the indwelling catheter period is short [6]. But its shortcomings could not be neglected. As a pulsed solid-state radiation, the holmium laser fiber lightly vibrates during operation, so its operational accuracy might be somewhat lower than thulium laser [25].

Green-light laser

The green-light laser is converted from Nd: YAG laser: when Nd: YAG laser (wavelength of 1064 nm) passes through potassium titanyl phosphate (KTP) crystal in the laser resonator, the frequency is doubled with the wavelength being shortened to 532nm [26]. Thus, the green-light laser is generated and its spectrum turns into visible green light beam [7]. It is highly absorbed by hemoglobin with a penetration depth of 0.8 mm and a coagulation area of only 1–2 mm thickness. Consequently, it has so strong hemostatic effect that the blood vessels can be coagulated ahead of soft tissues, theoretically permitting precise incision without bleeding. He et al. initially reported that the 30-W front-firing green-light laser ERBT technique was effective and safe for treating NMIBC in 2014 [22]. Thereafter, many articles about green-light laser ERBT have been published. Based on its excellent hemostatic property and precise incision, multiple surgical techniques- including photoablation, vaporization, and en bloc enucleation of bladder cancer- have been developed. But most clinicians perform ERBT. Overall, the results were promising. It can adopt two laser irradiation methods: front- firing and side- firing, so it can be used for BC with different sizes and locations. However, there was no comparison between the two methods, and it is not clearly elucidated which is better [1].

Thulium laser

Thulium laser was initially applied in Urology in 2005. Its wavelength is 1.75–2.22 μm, with an average of 1.940 μm, much closer to the water absorption peak value [27]. So it is also called 2 μm laser. Its penetration in water is 250 μm and thermal damage depth is only 200µm [7]. During surgery, thulium laser can be absorbed by water in the tissues, achieving rapid and precise resection. Compared with other lasers, thulium laser has special advantages: perfect hemostatic and steady control abilities, with smaller thermal damage.

Two types of thulium lasers are usually applied in urology: thulium: YAG (Tm: YAG) laser and thulium fiber laser (TFL). Tm: YAG energy output is continuous and produces a high mean energy output, resulting in a significant charring effect on tissues. Conversely, TFL is a pulsed laser with a theoretical penetration depth is no more than 150µm [28]. Furthermore, TFL does not burst tissues, allowing for precise, effective and smoother incision. However, thulium laser can cause mild carbonization, which is slightly inferior to holmium laser (as shown in Fig. 1).

Fig. 1

(A): mild carbonization is formed during thulium laser ERBT. (B) almost no carbonization is formed during holmium laser ERBT

Diode laser

Several types of diode lasers are applied clinically, including wavelengths of 450 nm, 980 nm, 1470 nm, etc. [21]. Their penetration depth is about 3 nm, with absorption by water and hemoglobin in the tissues. Their main advantages are superior hemostatic performance and fewer accidental injuries in deeper tissues, more efficacious for patients taking antiplatelet and anticoagulant therapy.

450 nm diode laser- blue laser

Blue lase- a newly developed 450 nm wavelength diode laser, can be used for vaporization, ablation and coagulation of various soft tissues. Clinical studies showed that compared with other visible or infrared lasers, blue laser has relatively shorter wavelength and higher absorption in soft tissues [27]. During operation, simultaneous ablation and coagulation occur to occlude tissues and blood vessels, resulting in less bleeding.

In a clinical study, Kaijie Wu et al. conducted a randomized controlled trial in five medical centers to assess the efficacy and safety of blue laser ERBT (85 patients), as compared to conventional TURBT (89 patients). They used blue laser equipment with a front-firing fiber and found that both techniques could effectively dissect all visible bladder tumors, but the blood loss was much less in blue laser group (p = 0.003), and the blue laser ERBT patients showed a faster wound healing at 3 months post-operatively. So they concluded that front-firing blue laser ERBT was not inferior to TURBT and much more convenient to perform [23].

1470 nm diode laser

In the laser absorption spectrum, 1470 nm wavelength diode laser is readily absorbed by water and hemoglobin, allowing for rapid resection and hemostasis with a coagulation thickness of about 400µm [29]. In a clinical study, 50 patients with NMIBC underwent 1470 nm laser ERBT. The operation time varied between 10 and 99 min, with a mean of 28 ± 13.9 min; and the amount of intra-operative blood loss was negligible [30]. Due to many advantages, such as thin coagulation zone in deeper tissues and almost no need for secondary electrocoagulation [18], some patients even received this operation under local anesthesia in the outpatient clinic [31].

In general, specific wavelength diode laser corresponds to specific device. Compared with other laser device, the diode laser device is smaller and needs no high voltage lines, making it easier to be carried and transported. Hence, it is becoming a hot research topic in BC treatment.

Surgical technique and procedures

The principle of laser ERBT is: by use of laser beams with different wavelengths and penetration depths, an entire bladder tumor is resected from the base and surrounding tissues.

During surgery, the patient is generally placed in a lithotomy position with normal saline as irrigation fluid. A laser fiber is introduced in the working sheath of a continuous-flow resectoscope, followed by careful observation of the whole bladder to identify tumors- the number, size, macroscopic appearance, and location. Initially, a circumferential incision is made with a safety margin of approximately 5 mm away from the normally appearing mucosa. The resection then proceeds vertically deep into the muscular layer, combining laser incision with blunt dissection of the resectoscope tip. Progressive detachment of the lesion is continued to expose and lift the tumor base, with careful blunt dissection along the loose space between the muscular layer and the connective tissue layer. In case of minor bleeding, coagulation is achieved with laser; and if there is adhesion or difficult separation of muscle fibers, laser is generated to cut from the tumor base. The entire tumor is removed with detrusor muscle beneath the base. Subsequently, the whole tumor bed plus the surrounding edges are adequately coagulated. In the process, it is important that the deep muscle layer is carefully identified to avoid perforation or losing vison. The procedures for thulium ERBT are illustrated in Fig. 2.

Fig. 2

(A): overall view of the bladder tumor. (B): procedure of thulium laser ERBT: circumferential incision 5–10 mm away from the tumor base. (C): procedure of thulium laser ERBT: resection proceeding to the deep muscle layer. (D): procedure of thulium laser ERBT: en bloc resection almost finished

Many clinicians consider that the difficult sites for ERBT are the dome and anterior wall. Some even propose it unfit for ERBT. However, we think this is not a contraindication to laser ERBT if performed cautiously. Our experiences for these cases are: the bladder is semi-filled with irrigation fluid, and an assistant presses the suprapubic region near the site of the tumor to expose it as clearly as possible. The resection is performed from sides, gradually progressing to the tumor center. More importantly, the tumor base is pushed and lifted by use of the resectoscope sheath combining with intermittent laser resection, so as to avoid perforation. In addition, for tumors near the ureteral orifice, double J stent is suggested to insert into the ureter in case of ureteral injury. Nevertheless, different from the procedure of TURBT, the stent can be removed once laser ERBT is completed if the orifice is not damaged, because laser energy brings about no thermal injury [32].

The final and important step of laser ERBT is to extract the tumor specimen entirely. Mostly through the resectoscope sheath, or occasionally via the urethra after removing the sheath, the extraction procedure varies based on the size of the specimens. For specimen < 3 cm, it can be flushed through the working sheath as per the siphon effect, or an Ellik evacuator, or a specimen retrieval bag. However, for specimen > 3 cm, the extraction procedures have not reached a consensus, as the entire tumor is difficult to pass through the resectoscope sheath. Some suggested to divide a large specimen into two or more parts; and some even proposed to use a morcellator [33]. But others argued this against the principal tenet of oncological surgery: complete removal of tumor with intact specimen, and these procedures would make pathologists unable to evaluate the intact specimen [32]. This issue needs further research on technology and medical instrument.

A second TURBT, usually performed within 2 to 6 weeks of the initial procedure, is recommended in several Clinical Guidelines for patients with large tumor bulk, T1/G3 or multiple tumors. Currently, there is no consensus as to whether second laser ERBT is necessary after initial laser ERBT. This issue is also concerned by some researchers [2]. Some researchers found that re-resection of the visualized scar with laser was feasible and safe without bladder perforation or uncontrollable bleeding. Furthermore, DM was obtained in all the specimens [34]. Actually, the surgical procedure of second laser ERBT after initial TURBT are almost similar to initial laser ERBT, as seen in Fig. 3.

Fig. 3

Procedures of second thulium laser ERBT. (A): circumferential incision away from the initial TURBT margins. (B): resection proceeding to the deep muscle layer. (C): progressive detachment with the tumor base being lifted with resectoscope tip. (D): the whole tumor bed and the surrounding edges are coagulated after overall resection

Advantages and limitations

The essential and main advantages of laser ERBT are its accurate pathological diagnosis owing to complete removal of the whole tumor. Unlike TURBT causing tumor fragmentation and tissue destruction which contradicts the basic oncologic principles, laser ERBT achieves acquisition of enough specimens with excellent quality: the tumor base remaining intact for pathological assessment of the resection margins, as well as evaluating the specimen orientation. More importantly, clinical studies have shown that DM was present in almost all specimens of laser ERBT [35]. It is well known that presence of DM is the most reliable indicator for an adequate and high-quality resection, and is crucial for guiding of the management strategy. This is also one of the main reasons for re-TURBT. Other evidence demonstrating the better resection quality of laser ERBT is to analyze whether recurrence occurred within the former ERBT area (in field) or distant (out-of-field) [36]. Literature showed that in-field BC recurrence occurred in about 4%, whereas other research groups found no in-field recurrence within their laser ERBT cohort with a follow-up period of 12–24 months. All these data are much lower than the TURBT groups [37]. In addition, clinical studies have shown that the identification rate of muscularis mucosa (MM) is higher in laser ERBT specimens. The plain clarification of cancer infiltration depth in the MM enables sub-staging of T1 tumors, thus improving the stratification accuracy of patients with high-risk NMIBC for progression-free survival (PFS), as well as leading to more reliable prediction for relapse and progression [32].

Another advantage of laser ERBT- especially thulium laser- is its excellent performance in hemostasis. Different from the easier formation of encrustation when using electrocautery during TURBT, a “coagulation layer” is formed during laser ERBT: the exposed tissue could be vaporized after being heated to a temperature of 90–100℃; while for the tissues adjacent to the vaporized part, it could be coagulated at 60–80℃. The instantly coagulated tissue layer renders hemostasis more efficiently, and eliminates diathermy artefacts. Moreover, the nutrient vessels around the tumor base are pre-blocked. Consequently, the tissue bleeding is controllable, and the surgical field is clearer, which allows for better control of resection depth and safety margin. Furthermore, a thin layer of tissue coagulation not only decreases the opportunity for detached tumor cells to be implanted, but also lowers the risks for postoperative urinary tract infection or swelling [38].

Bladder perforation is a serious complication occurred during TURBT, especially when the tumor locates in the lateral wall or dome. It can increase the risk of severe bleeding and prolong the catheterization and hospitalization duration. Most patients of bladder perforation are related to thermal injury and ONR. Both medical theories and practice have proved that thermal injury is the main cause for TURBT complications, due to the radiofrequency that had developed an electrical resistance at a temperature ranging between 100 and 300 °C in the surgical area [8]. Stimulation of the ONR, as a significant side effect during TURBT, can cause sharp muscle contraction and leg jerking leading to iatrogenic bladder perforation, even iliac blood vessel injury. However, during laser ERBT, the laser probe remains in a non-contact state with the mucosa, and no electrical current passes through the tissue and surrounding nerves, thus ONR can be eliminated, which is particularly useful for large lateral wall tumors. It is particularly suitable for patients with cardiac pacemaker or arrhythmia; as in such patients, the electrical current of TURBT may interfere with the pacemaker, or induce or aggravate arrhythmias. Additionally, laser ERBT procedures can be performed under a sacral block, which is important in current Chinese medical field. Because with the Diagnosis Related Groups (DRGs) policy implementation in China for the main goal of controlling medical expenses, the cost of sacral anesthesia is much lower than general anesthesia.

It is undeniable that laser ERBT is not yet a perfect surgery, as its limit lies in very large tumor which might require additional extraction methods. Complete resection of very large BC requires excellent surgical skill, otherwise bladder perforation may result from loss of surgical visual field. Very large tumors can’t be extracted through the resectoscope without being damaged or broken, thus the pathological examination is negatively influenced. Many publications showed that approximately 30% of bladder tumors could not be completely removed with laser ERBT, mainly due to tumor location or size [21].

This technique requires surgeons to proficiently master the laser characteristics and anatomy of the bladder and tumors. During surgery, the end-firing laser fiber could be somewhat cumbersome to manipulate, because the laser can’t change direction in the same medium, making it difficult especially when the lesion itself obscures the laser beam. So, the surgeon needs carefully controlling resection depth and appropriate laser power. A recent review of randomized clinical trials showed that laser EBRT had a longer operative time than TURBT [14]. The learning curve is accordingly longer than conventional TURBT, and imposes additional economic burden to patients. However, we think that, this situation will improve as the surgeons become more skilled. Table 2 lists a few clinical studies comparing laser subtype and TURBT in terms of operational time, complications and recurrence.

Table 2 Clinical studies comparing laser subtype and TURBT in terms of operational time, complications and recurrence

In summary, laser ERBT adheres to the fundamental principles in cancer surgery- resection of the tumor in one piece, complete resection with a safe margin, intact specimen for accurate histologic assessment, as well as avoiding fragmentation and tumor seeding. There is still room for further refinement.

Reduction of inflammatory response

While removing the tumor, TURBT triggers a local inflammatory response. It is well known that the inflammatory response has a dual role. Moderate inflammation could promote tissue repair and activate anti-tumor immune. But excessive inflammation can increase the risk of complications and recurrence through multiple mechanisms [43]: tissue damage and edema of the bladder wall, delayed healing, increased bleeding risk, thermal-related injury, as well as promoting fibrosis and infection risks.

A small number of studies have been undertaken to compare the inflammatory responses between laser ERBT and conventional TURBT. In 2024, Jin Yongsheng et al. investigated the effects of holmium- ERBT on inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6)) in NMIBC patients. In their study, 41 patients received holmium-ERBT and 41 received TURBT. They found that as compared with pre-operation, the postoperative levels of TNF-α and IL-6 were higher in both groups. But when comparison between the two groups 1 month postoperatively, the levels of TNF-α and IL-6 in holmium group were lower than TRUBT group. Thus, they concluded that holmium-ERBT has better efficacy than TURBT by reducing the inflammatory response of patients [44].

Similarly, Ma Guang et al. compared the clinical effects and postoperative inflammatory responses between laser ERBT and plasma electrosurgery in high-risk NMIBC patients. They found that laser ERBT group had lower hemorrhagic volume, shorter durations of bladder irrigation and catheter indwelling, shorter hospital stay, and lower overall complication rate, all with statistical significance (P < 0.05). Meanwhile, the levels of serum inflammatory factors, including high mobility group protein 1 (HMGB1), IL-6 and TNF-α, were all lower in the laser group than in electrosurgery group (P < 0.05). After follow-up of 2 years, the recurrence and metastasis rates were lower in the laser group (P < 0.05). They concluded that laser ERBT had a reliable clinical effect, and could effectively reduce postoperative inflammatory responses. We all know that HMGB1 represents the effect of inflammatory cytokines, with its increment causing and aggravating inflammatory response. IL-6 and TNF-α are pro-inflammatory factors, with their increment indicating that the surgical trauma results in aggravation of inflammatory response. These results showed that laser ERBT has noticeable advantages in reducing surgical trauma at molecular level [45].

In conclusion, laser ERBT reduces the body’s inflammatory response, thereby improving surgical safety and decreasing recurrence rate. These studies provide a scientific basis for the application of laser technology in BC treatment.

Future directions

Although laser ERBT has some comparative advantages as an emerging technology, it is yet to be improved. The search for easier and safer treatment modalities for BCa is always ongoing, particularly, when integration of novel devices or new theories.

In their perspective article, Yongjun Yang et al. stated that laser ERBT under white light cystoscopy might ignore small or occult malignant lesions, especially carcinoma in situ (CIS). However, combining with the application of newly-developed optical enhanced imaging technology, laser ERBT could tackle all possible recurrence mechanisms and achieve precise diagnosis and treatment of NMIBC. Such enhanced imaging technologies, including photodynamic diagnosis (PDD) and fluorescence-guided imaging, have improved the detection rate of BCa and highlighted the tumor margins. Photosensitizers can promote the concentration of reactive oxygen species inside cells, and aided for photodynamic therapy (PDT). Clinical studies have demonstrated that combining PDD-assisted ERBT and PDT is effective and safe as the first-line treatment of NMIBC, with adequate histopathological assessment of muscle invasion in tumor specimens, suggesting its clinical value in reducing the rate of re-TURT. In addition, fluorescence-guided imaging has shown important roles during ERBT, providing real-time guidance to delineate tumor boundary and residual diseases which are invisible to the naked eyes or computed tomography (CT). The results of human experiment demonstrated that fluorescence-guided imaging based on the near-infrared fluorescence probe targeting CD44v6 improved the detection rate of BCa with high-quality and complete resection [33].

In 2023, Jilu Zheng et al. integrated high-power (120 W) green-light laser (HPL) and en bloc endoscopic submucosal dissection (ESD) technique to treat NMIBC. At the beginning, the injector- containing diluted methylene blue solution as the injection fluid- was used to form the submucosal fluid cushion for ESD. Then HPL-ESD procedure was performed. Briefly, the multipoint submucosal injection was undertaken to loosen the tissue between the mucosal layer and the detrusor muscle, and a blue submucosal fluid cushion was formed. Subsequently, the HPL fiber was delivered and incising the mucosa annularly. Dissection of tissue linking the tumor and the bladder wall was facilitated as the submucosal fluid cushion had separated the mucosal layer and the DM layer. The entire tumor was then removed. Moreover, double‑J stent was not inserted in 4 patients whose tumors were adjacent to the ureteral orifice, without postoperative hydronephrosis. Therefore, they concluded that HPL‑ESD was safe and effective for the treatment of NMIBC, especially for tumors adjacent to the ureteral orifice [22].

A novel approach “rotatable bi-channel en bloc resection of bladder tumor (RBC-EBRT)” was developed in 2024. This specialized system allowed insertion of grasping forceps in the internal channel and the laser fiber in the external channel, because the authors thought that the single-channel system of laser ERBT limits its feasibility. The rotation of the channels enabled precise laser resection and traction of forceps, to reveal the resection line and maintain tension. The authors undertook an animal study, and found the resections were effectively performed in different regions of the bladder- the posterior, left, right, anterior walls and the dome. This study revealed that the RBC-ERBT technique enhances the feasibility of laser ERBT. This enhancement is credited to the dual working channel technique, allowing coordinated traction and resection, thereby improving visualization and accessibility of the target area. For lesions located in the anterior wall and dome where technical challenges were often significant, the RBC-ERBT technique was easy to operate. They considered this technique has several advantages. ⑴ The two working channels are placed in different sheaths, and both sheaths can rotate independently, allowing for better collaboration. ⑵ The rotatability of the working channel enables the laser to cut along an arc line, so leading to shorter operating time, as well as increasing surgical efficiency. And ⑶ the parallel orientation of both rotatable channels contributes to a smaller equipment diameter [1].

These new appliances present an opportunity to further develop the advantages of laser ERBT. In the future, the progression of laser ERBT will not only rely on the advancement of surgical technology, but also need to be deeply integrated with biomedical engineering, artificial intelligence and translational medicine, and ultimately achieve the more precise, minimally invasive and individualized treatment of BC.

Conclusion

Advances in medical technology have brought forth a multitude of strategies to the treatment of NMIBC, and ERBT is currently considered an ideal alternative to traditional TURBT in selected patients. Laser ERBT is attracting increasing interest due to several advantages: complete resection, intact specimen for accurate histologic assessment, avoiding fragmentation and tumor seeding, preventing obturator nerve reflex, and reduction of inflammatory response. Different energy sources of lasers have been studied in the application of ERBT: holmium laser, green-light laser, thulium laser, diode laser, etc. Laser ERBT conforms to oncological principles. But this technique is not perfect and there are more areas and problems that need to be studied and developed. Hence, we can see its advantage in certain cases. However, further basic and clinical studies are warranted to provide a better understanding of the oncological outcomes and more widespread adoption of the technique.