**3. Transurethral surgical ablation**

### **3.1 Symptom control**

If a Hunner lesion is confirmed by cystoscopy, transurethral surgical treatment should be performed. In 1971, Kerr et al. [14] first performed transurethral resection on a female patient with Hunner lesion who reported symptom relief for 1 year. In 2000, Peeker et al. [15] reported that 40% of patients who underwent transurethral resection of Hunner lesion had symptomatic improvement; the

remission rate was 34.5%, and patients remained in remission for 3 years after resection. In addition, Lee et al. [16] reported that combined hydrodistension and transurethral resection treatment increased bladder capacity and reduced the frequency of micturition and pain. Although the transurethral ablation methods, such as fulguration, coagulation, or resection of Hunner lesion, differ according to various studies, the pain visual analogue scale (VAS) significantly improved after transurethral ablation.

We performed a prospective, observational study of 72 patients with IC/BPS with Hunner lesion who underwent transurethral ablation and followed patients for 3 years [17]. At one month after surgery, the mean number of frequency and mean number of urgency episodes decreased sharply to 5.5 times and 9.4 times, respectively. Over the 12-month follow-up period, the number of frequency, urgency and VAS pain score increased compared with immediately after primary ablation treatment; however, these indices were all significantly better, even after 12 months.

#### **3.2 Characteristics of recurrence**

As the extent of Hunner lesion increases, the patient's pain and urinary symptoms tend to become more severe. The ICSI and ICPI and the maximum bladder capacity are significantly associated with the extent of Hunner lesion [18]. Nevertheless, it seems unlikely that patients with multiple Hunner lesion or a wider extent of Hunner lesion are more likely to show recurrence. Akiyama et al. [18] performed hydrodistension with fulguration for Hunner lesion and evaluated the outcome according to the extent of Hunner lesion; the authors found that the extent of Hunner lesion did not predict the need for repeat hydrodistension/fulguration. In our previous study, we were also unable to identify predictive factors related to recurrence. Lower maximal cystometric capacity [odds ratio (OR) 1.01, 95% CI 1.001–1.013; P = 0.017] was the only predictive factor related to early recurrence within 12 months, but sex, presence of previous hydrodistension, and number of Hunner lesions did not affect early recurrence [17]. Han et al. [19] also examined the recurrence pattern and predictors of Hunner lesion; the number of Hunner lesions had no effect on recurrence and only the Pelvic Pain and Urgency/Frequency Patient Symptom Scale (PUF) bother score (OR 1.142, 95% CI 1.016–1.284, P = 0.026) was a predictor related to recurrence of Hunner lesion. A PUF bother score greater than or equal to 7.5 was identified as the predictive cut-off value for recurrence, with a ROC area of 0.690 (sensitivity: 67.9%, specificity: 62.5%). In summary, the predictors of Hunner lesion recurrence have not yet been clearly identified; recurrence or progression does not appear to be faster in patients with multiple Hunner lesions and severe symptoms at the time of initial diagnosis.

One study evaluated the recurrence patterns of Hunner lesion after transurethral ablation and showed that 21.8% of Hunner lesions recurred in the previous ablation site, 18.8% recurred in a de novo site, and 59.4% recurred in both previous and de novo sites [19]. We analyzed the recurrence pattern through prospectively collected data of IC/BPS patients with Hunner lesion who underwent transurethral ablation (data not yet published). In our cases, Hunner lesion recurred in 120 of 210 patients with a median follow-up of 32 months. Among patients with a first recurrence, the proportion of patients with recurrence at the previous ablation site was 50.8% (n = 61), while 6.7% (n = 8) had recurrence of a new lesion, and 42.5% (n = 51) had recurrence at both previous and new sites. Overall, 90% of patients had recurrence around the previous ablation site, and less than 7% showed recurrence at a new site. Endoscopic treatment for Hunner lesion shows good efficacy in alleviating symptoms for a specific period of time after the procedure, but ultimately does not prevent Hunner lesion recurrence. This is considered a natural course of IC/BPS with Hunner lesion disease with the characteristics of pancystitis. To prevent recurrence, the role of postoperative medication or intravesical treatment should be investigated. A recent pilot study reported that hydrodistension with fulguration of Hunner lesion plus maintenance DMSO therapy prolonged the recurrence-free time in patients with IC/BPS with Hunner lesion [20].

## **3.3 Does repeat treatment reduce recurrence?**

One question regarding the recurrence of Hunner lesions is whether endoscopic treatment helps to suppress recurrence. However, current research indicates this may not be the case. In a 30-month prospective study of IC/BPS with Hunner lesion treatment naïve patients, the median recurrence-free time after the first endoscopic ablation of Hunner lesion was 12.0 ± 1.6 months (95% CI; 8.9–15.1). After the second endoscopic ablation, the median recurrence-free time was 18.0 ± 5.1 months (95% CI; 8.0–28.0), which was slightly increased, but the difference was not statistically significant (p = 0.15) [17]. Nevertheless, if Hunner lesion recurs, repeat ablation should be performed. Repeated endoscopic ablation does not lower the recurrence rate, but it is the only way to significantly reduce pain and improve quality of life in a less invasive manner.
