Conventional TURBT is one of the most common technique for NMIBC treatment. However, complications such as intraoperative bleeding and obturator nerve reflex often occur [10]. Moreover, the exfoliated cancer cells during operation increase the risk of recurrence and metastasis [11]. Although bipolar resection has been reported to reduce the risk of complications when compared with monopolar resection, the results remain controversial [12, 13].
To overcome the limitations of TURBT, the laser has attracted clinicians’ attention. The first use of laser in urological surgery was reported by Staehler et al. in 1978 [14]. They described the transurethral vaporisation resection of urinary bladder tumours with an Nd:YAG laser. The development of the en bloc technique makes lasers be widely used for bladder tumour treatment [15]. This technique is characterised by high-quality specimens that are beneficial for pathological analysis, in which the detrusor muscle was found in 96–100% of cases. In addition, laser en bloc resection reduces the risk of scattered tumour cells during surgery [16]. The safety and efficacy of lasers including thulium laser, holmium laser, 2 µm laser and 1.9 µm vela laser have been verified in clinical practice [17–20].
Gregers G Hermann et al. found that the depth and width of 980 nm diode laser are suitable for NMIBC treatment in an in vitro model [21]. Gunnar Wendt-Nordahl et al. found that the 980 nm diode laser shows higher tissue ablation capacity and similar haemostatic properties compared with the potassium-titanyl-phosphate (KTP) laser in porcine kidneys. The depth of the coagulation zones was less than KTP laser, similar to transurethral resection of the prostate (TURP) [9]. A study from Clemente Ramos LM demonstrated that prostate vaporisation using the 980 nm diode laser with output power up to 120 w is effective and related to minimal morbidity [22]. The guideline of laser technique from European Association recommends the use of diode laser treatment as an alternative way to treat patients with bladder outlet obstruction and benign prostatic enlargement. The treatment might have perfect intraoperative bleeding control for patients who have received anticoagulant drugs or had bleeding disorders [23]. To date, no clinical study is available regarding the vaporisation resection of NMIBC with a 980 nm diode laser.
In this study, 40 patients with NMIBC underwent 980 nm diode laser en bloc resection of the bladder tumour. We found that the 980 nm diode laser could provide good haemostatic effects by means of a non-contact point-to-surface pattern for obvious blood vessel bleeding. When the laser came into contact with the tissue, a precise cut with minimal bleeding was made. As a result, the bladder irrigation time was significantly shortened, and none of the patients in the 980 nm laser group experienced delayed bleeding. The vaporisation and cutting effects of the 980 nm diode laser were perfect. As shown in Fig. 1, the 980 nm diode laser controlled depth and width of cutting, as well as precise excision of the complete areas between the deep muscle layer and serosa layer. No complications of heat injury occurred. As previous literature described, the first step of laser treatment is making a circular incision in the mucosa around the tumour. However, we found that this step was difficult or unnecessary in bulky tumours or some special locations. In our opinion, the resection can start from the accessible tumour boundary, cut into the muscular layer and then gradually expand in the areas between the muscular layer and the serosa. With the assistance of the sheath and water stream, we created an operative space between the tumour base and the serosa. The tumour was completely removed, thereby maintaining the integrity of the tumour. The bulky tumour could be easily removed from the bladder using the electrocautery resection loop. The accurate pathological results were obtained (Supplementary Fig. 1). In this study, a total of 11 patients receiving TURBT treatment were excluded because no muscularis tissue was found in the specimen. The 980 nm laser is safe to deal with the tumour in the lateral wall of the bladder for without obturator reflex occuring. In addition, there were some advantages compared with other lasers. The diode laser lacks a steam bubble effect similar to holmium and thulium lasers, which create steam bubbles whose energy may destroy tissue and affect visibility of operator [24]. And diode lasers have a smaller box size and a much higher wall-plug efficiency, i.e., how much of the main supply is converted into laser power, and a lower price[23].
There are some limitations in our study, including its retrospective nature and small sample size. And we investigated the patients treated in one hospital. The way in which the patients were enrolled may have introduced selection bias. Further prospective research needs to be carried out in the future.
In conclusion, 980 nm diode laser is an efficient and safe tool in transurethral resection of NMIBC using the en bloc technique. It has less perioperative complications and shortened bladder irrigation time compared with PK-TURBT.