En bloc resection is the new treatment standard for nonmuscle invasive bladder cancer (NMIBC) worldwide. In 2017, the European Association of Urology (EAU) started recommending en bloc resection along with conventional transurethral resection of bladder tumor (TURBT) . In 2019, a study from Waldbillig et al. that included over 200 urologists from Europe and developing countries reported that 34.8% of the respondents would go for en bloc resection whenever possible, 23.8% of the participants rarely use this technique, and only 12.8% never applied it.
We are approaching slowly but steadily a tipping point in the use of en bloc for NMIBC. More urologists around the world are moving from TURBT to en bloc resection. The main driving force behind this change is high rate of muscle layer (muscularis propria) detection offered by en bloc resection. Muscle layer detection translates into reliable assessment of the factors that may foretell the risk of disease progression. Moreover, it is a quality criterion for removal of all cancer cells at the surgery site. Muscle layer detection upon histopathological examination has been repeatedly proven to decrease the risk of understaging, recurrence, and progression [3,4]. In fact, the EAU guidelines demand repeat surgery if no muscle is found in the specimen . This makes muscularis propria the key indicator of the quality of NMIBC surgery .
Conventional TURBT, often fails to yield high-quality specimens. Indeed, according to an European Organisation for Research and Treatment of Cancer (EORTC) study that merged the data of over 2410 patients from multiple medical centers, the recurrence rate after initial resection of NMIBC varied greatly between institutions ranging from 3.5 to 20.6%. The most likely explanation for this discrepancy is the different levels of experience and attention of surgeons to detail . For example, Rouprêt et al. showed that skilled surgeons succeeded in obtaining a specimen with the muscle layer in 73.8% of cases after conventional TURBT, whereas beginners only achieved it in 61.3% of cases. Indeed, the use of an eight-item surgical checklist during TURBT that included the complete resection of the tumor improved recurrence-free survival .
On the other hand, a major issue with conventional resection may be the technique itself, as reported earlier. Cutting the tumor into smaller pieces makes it challenging to control incision depth, may complicate histopathological examination and contradicts the principles of cancer surgery in general [8,9]. Hansel et al. assessed the quality of specimens after TURBT and concluded that en bloc resection offers the most effective solution to the majority of these issues.
Introduced in 1997 by Kawada et al., this technique proved to be an effective tool ensuring the detection of the muscle layer in the specimen in the majority of cases. Kramer et al. reviewed over 20 articles on en bloc resection of bladder cancer and found out that the rates of detrusor muscle detection ranged from 87 to 100%. Moreover, en bloc resection techniques were proven to have equal efficacy and safety profiles, regardless of the source of energy used . Muscle layer detection rates also showed no significant differences (mean, 97%) . Soria et al. conducted research in four large medical centers on 300 patients which showed that en bloc resection is a reliable predictor of no repeat surgery in the future (hazard ratio 7.71; 95% confidence interval 1.57–37.84; P = 0.01).
In fact, not only does en bloc resection of bladder cancer allows for avoiding repeat surgery and improving staging, but it offers lower recurrence rates as well . According to Kramer et al., many researchers report infrequent recurrence at the surgery site after en bloc resection. Conversely, other published data puts recurrence rates at the site of initial resection in the range of 4–30%.
Some researchers point out several limitations of en bloc resection. Among them are location of the lesion and size over 3 cm. We believe, however, that skill and experience eventually mitigate the issue of location. Size should also not be the reason to refrain from en bloc resection as the resection can be divided into two stages for these tumors. The first step consists in the removal of the exophytic part of the tumor. The choice of technique is not critical here for grading will be possible anyway. The second step can be en bloc resection of the base of the tumor which allows for having high-quality vertical and horizontal surgical margins. Overall, from our experience, we believe that en bloc resection may be employed in the majority of cases.
In conclusion, published data suggest superiority of en bloc resection over conventional TURBT. It offers easier examination of the specimen resulting in lowered recurrence rates. Moreover, recent publications suggest that en bloc resection has already become routine . However, the standards of evidence-based medicine require a large-scale randomized trial that will inform as to which technique is better. Such a study is underway including multiple experienced centers (ClinicalTrials.gov NCT03718754). The first results will be upcoming year. Perhaps, they will aid in redefining approaches to bladder cancer management by ushering in the age of en bloc resection from NMIBC.
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