The study, led by Xinyu Zhang, Luhua Ji, and Yutong Lu as co-first authors under the corresponding authorship of Jun Mi and Zhiping Wang, enrolled 322 patients with non-muscle-invasive bladder cancer at a single center. Rather than running a tightly controlled trial, the investigators examined what actually happens in clinical practice, grouping patients according to the surgical technique they received. A total of 109 patients underwent narrow band imaging-assisted en bloc resection of bladder tumor, 96 received en bloc resection guided by conventional white light imaging alone, and 117 underwent the traditional white light-based TURBT. The primary endpoint was recurrence-free survival, while secondary measures included operative time, complications, catheterization duration, length of hospital stay, the rate at which the resection captured the detrusor muscle, and the presence of residual tumor found during secondary resection.

To understand why the findings matter, it helps to unpack the two technologies under scrutiny. Narrow band imaging, or NBI, is an optical enhancement technique built into modern endoscopes. Instead of bathing tissue in the full spectrum of visible light, NBI filters illumination into two narrow wavelength bands centered on 415 and 540 nanometers. These wavelengths correspond to the peak absorption of hemoglobin, so blood vessels and capillary-rich tissue absorb them far more strongly than surrounding structures. On the endoscopic display, malignant lesions and their vascular patterns stand out in dark contrast against the pale background of normal urothelium. Because early bladder tumors often betray themselves through subtle neovascularization before they form obvious masses, NBI gives surgeons a kind of optical biopsy, highlighting suspicious mucosa that white light might overlook.

En bloc resection of bladder tumor, or ERBT, is the second half of the equation. Conventional TURBT removes tumors piecemeal, shaving them away in fragments with a wire loop while cauterizing the base. That fragmentation has consequences: the tissue sent to pathology arrives in pieces, making it difficult for pathologists to assess whether the tumor’s base was fully excised and whether the muscular layer of the bladder wall—the detrusor muscle—was captured. Since the presence of muscle in the specimen is essential for accurate staging, and since floating tumor fragments can theoretically implant elsewhere in the bladder, the piecemeal approach has long been viewed as a weak link. ERBT, by contrast, circumscribes the tumor with a visible margin and lifts it off the bladder wall as a single intact specimen, preserving the tumor’s architecture and its deepest margin for pathological evaluation.

The Lanzhou team’s results paint a nuanced picture of what each technique contributes. In exploratory unadjusted pairwise comparisons, patients who received NBI-assisted en bloc resection enjoyed significantly longer recurrence-free survival than those treated with conventional white light TURBT, with a p-value of 0.047. When the analysis turned to the individual components, en bloc resection itself emerged as the driver of several benefits: it improved recurrence-free survival specifically in patients classified as low risk, it significantly increased the rate of detrusor muscle acquisition in the pathological specimens, and it shortened the duration of postoperative catheterization. These advantages held whether en bloc resection was paired with NBI or with white light alone, indicating that the intact-specimen technique is the workhorse behind better staging and faster recovery.

Narrow band imaging, meanwhile, earned its place in the operating room through a different mechanism. While NBI did not by itself extend recurrence-free survival in this cohort, it substantially reduced the rate of residual tumor detected at secondary resection. The comparisons between the NBI-ERBT group and both the white light ERBT group and the conventional TURBT group reached statistical significance, with p-values of 0.043 and 0.004 respectively. This finding speaks directly to one of the most feared complications of bladder tumor surgery: incomplete removal. If tumor cells are left behind at the resection site, they can seed recurrence and, in some cases, progress to muscle-invasive disease. By illuminating vascular signatures invisible under white light, NBI appears to help surgeons confirm that the margins are truly clear before the operation ends.

Importantly, the combined approach did not come at the cost of efficiency or safety. The study found no significant differences among the three groups in operative time, complication rates, or length of hospital stay. That null result is clinically significant in its own right, because a common argument against adopting enhanced imaging and more meticulous resection techniques is that they slow the operation down or increase perioperative risk. The Lanzhou data suggest that NBI-assisted ERBT can be folded into routine practice without extending the patient’s time under anesthesia, and that the improved postoperative recovery seen with en bloc resection—shorter catheterization in particular—translates into a more comfortable hospital course.

The authors are candid about the limitations of their work. As a single-center, retrospective cohort study, it cannot eliminate the possibility of selection bias: surgeons may have chosen one technique over another based on tumor characteristics or patient factors that the analysis did not fully capture. The pairwise comparisons were described as exploratory and unadjusted, meaning the p-values should be interpreted with appropriate caution rather than as definitive proof of superiority. Real-world data of this kind are valuable precisely because they reflect everyday practice, but they require confirmation from prospective, ideally multicenter, randomized trials before NBI-assisted ERBT becomes a universal standard of care. The study was supported by the National Natural Science Foundation of China and the Cuiying Plan Project of Lanzhou University Second Hospital, and the authors declared no competing financial interests.

Even with those caveats, the study lands at a moment of genuine momentum for optical enhancement in urology. Bladder cancer surveillance already depends heavily on cystoscopy, and the same narrow band imaging technology used in the operating room can be applied during follow-up examinations to detect recurrences earlier. If the recurrence-free survival benefit observed here is confirmed in larger trials, the implications for health systems are considerable: fewer repeat resections, fewer surveillance procedures triggered by early recurrence, and more accurate staging that ensures patients with higher-risk disease are escalated to appropriate adjuvant therapy, such as intravesical immunotherapy with agents instilled directly into the bladder.

For patients, the takeaway is more personal. A diagnosis of non-muscle-invasive bladder cancer, while serious, is highly treatable, and the quality of the first resection is one of the strongest predictors of what follows. An operation that removes the tumor whole, confirms clear margins under enhanced light, delivers the muscle layer to the pathologist, and lets the catheter come out sooner is not a futuristic vision—it is a combination of existing tools whose benefits this study begins to quantify. The Lanzhou findings do not close the case, but they strengthen the argument that how a bladder tumor is removed matters as much as the fact that it is removed, and they give surgeons and patients alike a concrete reason to ask whether their operating room offers narrow band imaging and en bloc technique when that first, crucial surgery is planned.

Subject of Research: Narrow band imaging-assisted en bloc resection for non-muscle-invasive bladder cancer

Article Title: Narrow band imaging-assisted en bloc resection improves clinical outcomes in non-muscle invasive bladder cancer: a single-center real-world cohort study

Article References: Zhang, X., Ji, L., Lu, Y., Ma, J., Yang, E., Zhang, Y., Zhai, Z., Mi, J., & Wang, Z. (2026). Narrow band imaging-assisted en bloc resection improves clinical outcomes in non-muscle invasive bladder cancer: a single-center real-world cohort study. BMC Cancer. https://doi.org/10.1186/s12885-026-17046-3

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17046-3

Keywords: bladder cancer, narrow band imaging, en bloc resection, TURBT, non-muscle-invasive bladder cancer, recurrence-free survival, detrusor muscle, residual tumor, endoscopy, urology, surgical oncology, cohort study