En bloc resection has the potential to improve outcomes in patients with non-muscle invasive bladder cancer (NMIBC) compared with standard resection, according to investigators.

In the multicenter, randomized phase 3 EB-StaR trial, which compared the surgical approaches in patients with tumors measuring 3 cm or less, investigators found that patients having an en bloc resection had a significantly lower 1-year recurrence rate (the trial’s primary outcome) compared with those undergoing standard resection (28.5% vs 38.1%).

“Bladder tumors are resected in a piecemeal manner,” said Jeremy Teoh, MD, an assistant dean and associate professor of urology at The Chinese University of Hong Kong, who presented the study findings at the American Urological Association’s 2023 Annual Scientific Meeting. “It is difficult to ensure a complete and uniform tumor resection down to the detrusor muscle layer. Therefore, residual tumor can be present even after standard resection.”

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During standard resection, tumor cells float inside the bladder, Dr Teoh explained. The tumor cells can re-implant to the bladder mucosa and lead to early disease recurrence.

For EB-StaR trial, the investigators randomly assigned 276 patients with histologically confirmed NMIBC to receive an en bloc procedure (143 patients, mean age 69.6 years, 75.5% male) or undergo standard resection (133 patients, mean age 69.1 years, 82.7% male).

The 1-year progression rate was 0% in the en bloc group and 2.6% in the standard resection arm, a nonsignificant difference. The en bloc group had a significantly longer operative time compared with the standard resection group (33.4 vs 24.7 minutes).

All other outcomes were similar between the treatment arms, according to investigators. These included the detrusor muscle sampling rates, occurrence of obturator reflex, use of postoperative mitomycin C instillation, 30-day complication rate, hospital stay, and residual disease and upstaging of disease.

“En bloc resection is a potentially superior technique in treating bladder cancer,” Dr Teoh said. “It is important to have a large-scale multicenter randomized trial to investigate whether en bloc resection can lead to a better oncological control in patients with non-muscle-invasive bladder cancer. With en bloc resection, complete resection can be ascertained not only by the surgeon’s judgment, but also based on the histological assessment of the resection margins of the en bloc resected specimen.”

If en bloc was widely adopted, it could help minimize tumor fragmentation and the risk of tumor re-implantation, he said. “I strongly believe oncological principles exist for good reasons. En bloc resection aims to uphold all oncological principles, and I am not surprised it did lead to a better oncological control,” he said. “As urologists, we should try our best to perform high-quality surgery in order to deliver the best possible outcomes.”

Impact on More Aggressive Tumors Unclear

Chad R. Ritch MD, MBA, associate professor of urologic oncology within the Desai Sethi Urology Institute at the University of Miami’s Miller School of Medicine in Florida, said the current study is notable because it could lead to increased use of en bloc in this patient population. “While it is technically feasible for smaller tumors, those cancers are generally not that aggressive, and recurrences can be managed with repeat resection and intravesical therapy without a major impact on survival,” Dr Ritch said. “What remains to be seen is whether this technique is going to be impactful in the larger, more aggressive tumors where recurrences and progression can be more dangerous.”

The study was well designed and could have significant clinical implications, he said. “Randomized controlled studies like these are important because they assess novel surgical techniques in a thoughtful and meticulous manner, thereby eliminating much of the biases introduced by patient selection for one approach over the other,” Dr Ritch said. “Endoscopic resection in NMIBC has not changed over many decades, and it is important to introduce new technologies, safely, through well designed studies such as this.”

Standard Resection ‘Antiquated at Best’

Sam S. Chang, MD, MBA, professor of urology and medicine and chief surgical officer at the Vanderbilt Ingram Cancer Center in Nashville, Tennessee, said the standard resection techniques are antiquated at best. “The authors should be applauded in performing a randomized trial to evaluate the possible beneficial impact of an en bloc resection. As with any new technique, how results will translate in real world situations is still unknown.”

While the new findings are intriguing, he noted, much larger studies with longer follow-up may help better define the benefits and risks of en bloc. “We know for certain tumors, this technique may not be possible or the best technique,” Dr Chang said. “Careful studies evaluating our current diagnostic, therapeutic, and surveillance management are essential to escalating care when needed but also de-escalating care when appropriate.”

Roger Li, MD, a genitourinary surgeon at Moffitt Cancer Center in Tampa, Florida, said while the investigators are to be congratulated for conducting this randomized study, the participants enrolled had tumors measuring 3 cm or less, representing patients on the lower end of the risk spectrum in NMIBC. “These tumors tend to be adequately managed with resection alone or with perioperative chemotherapy infusion,” Dr Li said. “The theoretical risk of tumor cell implantation has not been definitively proven. In addition, postoperative chemotherapy administration may serve to eliminate the phenomenon of tumor cell implantation and thus abrogate the perceived risk associated with standard TURBT.”

Longer Operative Time ‘Not Trivial’

He added that the longer operative time is not trivial, as multiple procedures are typically performed back-to-back. While the study shows the feasibility of en bloc resection and that it may reduce recurrence rates in patients with small tumors, it remains to be seen how many patients would be candidates. “The inaccuracy of bladder cancer staging obtained through endoscopic resection has been well described,” Dr Li said. “En bloc resection is a method that has been proven to work well in the setting of smaller tumors, providing the anatomical specimen to the pathologist for straightforward evaluation. However, given the constraints to remove larger specimens transurethrally, the clinical impact of en bloc resection is still to be determined.”


Teoh J, Chan TY, Tsang I, et al. Transurethral en bloc resection versus standard resection of bladder tumor: A multi-center randomized trial (EB-StaR Study). Presented at: AUA 2023, Chicago, Illinois, April 28-May 1. Abstract PD13-11.