In total, 144 urologists (24.7%) responded to the survey. From these, we excluded three urologists who were not actively in practice or did not manage complex cysts, and two urologists because they did not answer any questions other than demographics. Therefore, our study included 139 respondents, of which 88.8% (N=122) answered every survey question.
Demographic data are presented in Table 1. Of the eligible respondents, 71 (51.1%) practiced in an academic center, while 68 (48.9%) practiced in a non-academic setting. The majority (87.0%) of respondents reported managing ≤20 new complex renal cysts on an annual basis.
Use of active surveillance
Of the eligible respondents, 13.7% of urologists never or rarely (<5% of cases) offered active surveillance, while 33.1% offered active surveillance in >50% of patients with a Bosniak III cysts in whom surgical excision is considered a suitable treatment option (Figure 1). When compared to non-academic urologists, a significantly greater proportion of academic urologists offered active surveillance as a treatment option to their patients with a Bosniak III cyst. When patients with a Bosniak III cyst were offered active surveillance as a treatment option, it was perceived by nearly half of the urologists (45.7%) that this option was accepted in a majority of cases. The likelihood of a patient accepting active surveillance for the management of a Bosniak III cyst was perceived to be significantly greater by urologists from academic centres than by urologists from non-academic centres.
Unlike for Bosniak III cyst, a majority of urologists (60.1%) never or rarely (<5% of cases) offered active surveillance for Bosniak IV cysts, while only 10.1% offered active surveillance in >50% of cases. A significantly greater proportion of academic than non-academic urologists viewed active surveillance as a viable treatment alternative for patients with a Bosniak IV cyst. However, even when active surveillance was proposed to a patient as a treatment option, only 20.4% of urologists stated that this option was accepted by >50% of patients.
Barriers to active surveillance adoption
Several potential barriers to a greater adoption of active surveillance were noted (Table 2). The most commonly reported ones were  the patient's and physician's concerns regarding the oncologic safety and/or benefits of active surveillance (89.8%),  the lack of data supporting active surveillance in patients with Bosniak III-IV cysts (74.2%), and  the lack of specific triggers for intervention during surveillance for complex renal cysts (75.8%).
Factors increasing likelihood of offering active surveillance
For both Bosniak III and IV cysts, age and the presence of comorbidities were perceived as having an impact on the likelihood of a patient being offered active surveillance as a treatment alternative (Table 3). The majority of urologists viewed older patients (>75 years of age) as being ideal candidates. Nevertheless, nearly 30% of urologists thought that the lower age cut-off should be 65 years old for patients with Bosniak III cysts. Likewise, most urologists viewed that cyst size influenced their decision to offer surveillance and that cysts <4 cm were ideal for active surveillance.
More specifically, for Bosniak III cysts, the presence of cyst wall nodularity (74.8%) and the maximal thickness of septa/calcification (44.1%) were also considered characteristics that impacted the likelihood of offering active surveillance. An upper limit threshold of 3 mm (IQR 2-5 mm) in maximal thickness of septa/calcification was perceived as being most appropriate for surveillance. For Bosniak IV cysts, the size of the nodular component was seen as important to the decision to offer active surveillance (69.9%) with a median perceived upper limit cut-off of 2 cm (IQR 1-3 cm).
Triggers for intervention during active surveillance
Several characteristics were perceived by urologists as being criteria for intervention for patients initially managed by active surveillance (Table 4). The most commonly reported criteria for Bosniak III cysts were  progression on imaging from Bosniak III to IV cysts,  worsening or change in the wall or septa enhancement,  progression or development of cyst wall nodularity. For Bosniak IV cysts, the two most common triggers for intervention were perceived as being  the growth rate of solid component (>0.5 cm/year) and  the growth of solid component (>3 cm).
When managed surgically, over half of respondents (57.3%) were more likely to offer a minimally invasive partial nephrectomy approach to patients with a complex cyst as the surgical management of choice. No significant differences in terms of surgical management were observed between academic and non-academic urologists (Appendix 2). When compared to the management of small non-cystic renal masses, the majority of surveyed urologists managed Bosniak III and IV cysts in a similar fashion to how they manage small non-cystic renal masses. However, 20.7% of respondents were more inclined to offer an open surgical approach, while 14.6% were more inclined to perform a radical nephrectomy as opposed to a partial nephrectomy. Again, there were no statistically significant differences observed in the management of academic and community urologists (Appendix 3).