We aimed to present the characteristics, recurrence and bladder overactivity rates of patients who were diagnosed with muscle noninvasive bladder cancer (NMIBC) and who underwent intravesical immunotherapy (BCG).

We reviewed the data and results of 130 patients (male: 111, female: 19) who had been diagnosed with NMIBC between March 2012 and May 2018 (90% high risk, 10% moderate risk group) and underwent intravesical BCG. Patients were evaluated in terms of age, body mass index (BMI), smoking status, pathological stage, histologic grade, duration of BCG treatment, recurrence rates, cystectomy rates, bladder filling phase symptoms requiring medical treatment (frequency, urgency).

The mean age of the patients was 61.3 ± 10.7 (31-82) years; mean BMI was 26.9 ± 3.8 kg/m2 (18-39). 108 (79.2%) patients had a history of smoking. The number of patients who had previously received intravesical chemotherapy and induction dose BCG alone was 10 (7.7%) and 28 (21.5%), respectively. The rates of patients with stage pTa, pT1 and pTis were 57.7%, 40% and 2.3%, respectively. When evaluated according to their histological grade, the rates of low grade (LG), high grade (HG) and in situ carcinoma (CIS) were 21.5%, 76.2% and 2.3%, respectively. The presence of CIS in all patients was 52.3%. The mean duration of intravesical BCG administration was 10.23 ± 10.53 (0.5-36) months. Patients had symptoms of bladder filling phase that required medical treatment within an average of 8.74 ± 8.22 (1-24) months after BCG was initiated.

 	The number of patients received induction therapy was 61 (46.9%), the number of patients received maintenance therapy for 12 months or less was 23 (17.7%) and the number of patients received maintenance therapy for more than 12 months was 46 (35.4%). Tumor recurrence rates of these patients were 59%, 43.5% and 6.5%, respectively (p <0.0001); The frequency of bladder filling phase symptoms requiring medical treatment was 13.1%, 30.4% and 52.2% (p <0.0001). According to these results, two values were statistically significant in patients receiving maintenance BCG therapy (≤ 12 months and> 12 months) compared to patients who received induction therapy for only 6 weeks (p <0.0001). During follow-up, 14 patients (10.8%) required cystectomy due to BCG non-responsiveness or disease progression.

The importance and the effectiveness of intravesical BCG administration time in the treatment of NMIBC was once again demonstrated. However, it should be kept in mind that as the duration of intravesical BCG application increases, the incidence of bladder cancer recurrence decreases. The frequency of side effects requiring medical treatment increases with the duration of therapy.

As the duration of intravesical BCG application prolongs (Especially in those who received maintenance BCG for at least 1 year), there will be an increase in symptoms of overactive bladder such as urgency and frequency, which will require medical treatment.