Patients with low-grade non-muscle-invasive bladder cancer (NMIBC) may require routine follow-up for as long as 10 years from the initial diagnosis, according to Japanese investigators.

In a retrospective study of 190 patients (mean age 62.9 years) who underwent transurethral resection for NMIBC, 82 patients (43.2%) had tumor recurrence and 21 (11.1%) had worsening progression (WP) after a median follow-up of 101.5 months, Hiroaki Kobayashi, MD, and colleagues at Keio University School of Medicine in Tokyo reported online in BMC Urology. The average time to WP was 82.4 months.

Eleven patients (14.5%) experienced late recurrence, defined as recurrence after being tumor-free for more than five years from initial transurethral resection. Of these, five (6.6%) experienced late WP. Patients experienced late recurrence and late WP after an average of 103.5 and 104.5 months, respectively, after surgery.

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The authors noted that about 50%-70% of patients with NMIBC experience recurrence within five years after treatment and 5%-20% progress to invasive tumors.

Solitary and multiple tumors were present in 114 and 76 patients, respectively. The five-year recurrence-free and WP-free survival rates were significantly greater for patients with solitary rather than multiple tumors (68% vs. 45.9% and 97.2% vs. 85.5%, respectively). Compared with patients who had solitary tumors, those with multiple tumors had a threefold increase risk of recurrence and a fivefold increased risk of worsening progression. In addition, the absence of intravesical instillation was associated with a threefold increased risk of recurrence.

No patient died from bladder cancer during follow-up, the investigators reported.

The researchers defined recurrence as the occurrence of a new tumor in the bladder and worsening progression as 

  1. confirmed high-grade Ta, all T1, or Tis/concomitant carcinoma in situ of bladder recurrence
  2. upper urinary tract recurrence
  3. progression to T2 disease or greater

Of the 190 patients, 71 (37.4%) and 12 (6.3%) received intravesical BCG and mitomycin C, respectively.

Contrary to the findings of previous studies, the investigation by Dr. Kobayashi’s group found no association between smoking status and recurrence rate, WP rate, or late recurrence rate. One reason for their negative result, they noted, is the relatively lower percentage of smokers and lesser amount of smoking in Japanese NMIBC populations.

In a previous study of 262 patients who underwent transurethral resection of NMIBC and had no tumor recurrence for more than five years, tumors recurred in 39 patients (14.9%) after a median follow-up of 10 years, according to a report in Urology (2010;75:1385-1390). The researchers found five- and 10-year recurrence-free survival rates of 81.6% and 76.0%, respectively. Five patients (1.9%) experienced stage progression. Of these, three did not have metastases at the time of diagnosis of the progression but died from bladder cancer, the authors stated.