Outcomes

The earliest of series evaluating outcomes after partial cystectomy for MIBC date back to the 1970s. Novick and Stewart described a cohort of 50 patients with muscle‐invasive disease in which 5‐year cancer‐specific survival was less than 50% among patients with MIBC, with the survival rate being less than 20% for those with T3 disease [1]. A similar retrospective review of 45 patients by Schoborg et al. cited recurrence rates as high as 100% and 5‐year disease‐specific survival of less than 40% among patients with high‐grade lesions irrespective of stage [2]. The historically dismal prognosis associated with partial cystectomy, particularly in relation to total extirpative therapy, obscured its utility in the management of muscle‐invasive disease until only recently.

A critical review of these reports reveals that the indiscriminate use of partial cystectomy for patients with MIBC is in large part responsible for inferior treatment outcomes. The importance of disease selection has been borne out in several contemporary studies that demonstrate cancer control to have been highly comparable to radical cystectomy [3, 4]. Among patients with a solitary focus of muscle‐invasive disease who lack concomitant carcinoma in situ (CIS), a matched cohort comparison of both procedures performed by the Mayo Clinic found no significant differences between partial cystectomy and radical cystectomy with respect to 10‐year metastasis‐free survival (61% vs. 66%, P = 0.63) and cancer‐specific survival (58% vs. 63%, P = 0.67). Overall survival was also found to be similar between treatment groups [3]. These results echo that of a population‐based treatment comparison utilizing the SEER database, which demonstrates similar cancer‐specific and overall survival for unifocal muscle‐invasive disease amenable to complete resection with partial cystectomy [4].

Indications and contraindications

Success of partial cystectomy for management of MIBC is highly contingent on patient selection and nature of disease. As such, critical review of patient pathology and disease history is of paramount importance when determining eligibility. Among patients without lymph node metastasis or extravesical extension, pathologic features predictive of inferior recurrence‐free and cancer‐specific survival outcomes include tumor size >5 cm, need for ureteral reimplantation, and histologic evidence of lymphovascular invasion [6, 7].

Tumor multifocality on initial stages has also been deemed a relative contraindication to partial cystectomy [7, 8]. A review of 86 patients undergoing partial cystectomy for localized MIBC revealed a 3.4‐fold higher risk of 5‐year cancer‐specific mortality in the setting of synchronous lesions compared with unifocal disease [7]. Similarly, the presence of metachronous disease confers a poor oncologic outlook as cancer‐specific and recurrence‐free survival are reduced approximately threefold in patients with prior history of urothelial cancer [6]. Pathologic evidence of CIS during initial staging generally precludes partial cystectomy due to significant risk for development of intravesicular as well as advanced disease relapse [8]. Prior to planned partial cystectomy, random biopsies of the remaining bladder should be performed to confirm the absence of tumor multifocality or concomitant CIS.

Tumor location is not inherently predictive of oncologic outcomes [8]. Rather, the oncologic efficacy of partial cystectomy is highly dependent on the ability to achieve an adequate negative surgical margin. In this context, solitary tumors on the bladder dome or anterior wall are most amenable to partial cystectomy, whereas lesions situated at the trigone or bladder neck pose a technical challenge of achieving an acceptable disease‐free perimeter. No study formally evaluates the optimal extent of a negative surgical margin with partial cystectomy. However, consensus is that resection be performed to achieve a 2 cm margin devoid of malignancy. Tissue from the edge of the resection bed should be sampled by intraoperative frozen section to ensure the absence of residual disease. Positive surgical margins may insinuate a more infiltrative process for which radical cystectomy may be better suited. Lesions in the posterior or lateral wall are technically amenable to partial cystectomy, however, ipsilateral ureteral reimplant may be necessary to enable adequate resection, which invites increased risk for postsurgical relapse [6–8].

A reduction in bladder capacity can be expected after partial cystectomy and may result in urinary frequency or urgency. Eligibility is questionable in patients with severe baseline lower urinary tract symptoms or bladder dysfunction due to risk of exacerbation and perturbed quality of life.

Bladder‐preservation therapy

Data regarding the utility of neoadjuvant chemotherapy prior to partial cystectomy remains scant. Nevertheless, oncologic benefit is inferred based on prospective studies demonstrating a 5% reduction in cancer‐specific mortality after radical cystectomy [9]. Preoperative chemotherapy should therefore be considered in all patients eligible for partial cystectomy.

In comparison, chemotherapy has a more established role in alternative forms of bladder‐preservation treatment. Trimodality therapy (TMT), which also encompasses maximal transurethral resection and concurrent radiation, is similar to partial cystectomy in that patient selection is of paramount importance to achieve acceptable outcomes. Among medically operable patients, the presence of CIS, tumor multifocality, and hydronephrosis are considered high‐risk features and represent relative contraindications to TMT [10, 11]. In addition, large‐volume disease that does not lend itself to maximal resection would also preclude TMT [12]. Pooled analyses of trials evaluating the oncologic efficacy of TMT estimated cancer‐specific survival and overall survival to be 71% and 65%, respectively, at 5 years and 57% and 36%, respectively, at 10 years [13]. No prospective comparison to radical cystectomy exists. However, several long‐term retrospective studies evaluating radical cystectomy and TMT as well as recent studies utilizing national cancer registries demonstrate that radical cystectomy may offer superior cancer‐specific survival and overall survival on both multivariable and propensity‐matched analysis [12, 14, 15]. However, the differences may be marginal if stringent selection criteria for TMT are applied [16].

Patients being considered for bladder‐preservation therapy should be counseled on TMT and partial cystectomy in the appropriate setting. Currently, there are no comparative studies in the literature to evaluate the oncologic efficacy of each treatment. Given the significant overlap in eligibility criteria, advantages and disadvantages of both procedures should be emphasized to facilitate an informed decision. A clear benefit of partial cystectomy is the capacity to perform simultaneous pelvic lymph node dissection, which serves both prognostic and therapeutic value [17]. More accurate pathologic staging of the primary tumor is also possible due to full‐thickness resection, again enabling better prognostic stratification as well as the delivery of more tailored adjuvant and salvage therapies. Indeed, a report by Tritschler et al. demonstrated significant risk for pathologic understaging based on imaging alone due to limitations in the capacity of radiologic metrics to gauge local and systemic disease extent [18].

Surveillance is an integral component of both treatment strategies, given early detection of recurrence can optimize cancer control. The incidence of recurrence (both non‐muscle‐invasive and muscle‐invasive) after partial cystectomy is estimated to be 38%, whereas relapse among complete responders ranges between 24 and 43% after TMT [4, 13, 19]. Muscle‐invasive recurrence accounts for a relatively small proportion in both groups. The rate of salvage cystectomy is almost 20% after partial cystectomy and as high as 30% with TMT if taking into account the nonresponder cohort [3, 13, 19, 20].

Minimally invasive partial cystectomy

The advent of the robotic platform has encouraged a paradigm shift in the management of MIBC. Although robotic radical cystectomy is an increasingly utilized treatment option, a recent prospective study demonstrated no difference in pathologic outcomes and clinical metrics, including 90‐day complications rate, hospital length of stay, and six‐month quality of life [21]. Nevertheless, its non‐inferiority may justify constituency in the treatment armamentarium for this disease.

A formal comparison of robotic and open approaches to partial cystectomy remains to be performed. However, several retrospective studies have demonstrated favorable oncologic and perioperative outcomes associated with the robotic technique. The largest of these reviews revealed a 90‐day complication rate of 17%, with all having been minor in nature. In addition, median hospital stay in this cohort was only 1 day and median blood loss was only 50 ml [5]. In this context, a robotic approach to partial cystectomy is feasible in patients who meet eligibility criteria for bladder‐sparing treatment.

Patient preoperative evaluation and preparation

A diagnosis of bladder cancer is often prompted by microscopic or gross hematuria. Hematuria workup should ensue and encompasses cross‐sectional imaging of the abdomen and pelvis. Cytology should be considered in high‐risk patients as the presence of atypical or malignant cells warrants a thorough evaluation for high‐grade disease, particularly CIS [22, 23].

Contrast‐enhanced computed tomography (CT) remains the ideal imaging study, with emphasis placed on the excretory phase [22, 23]

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