[Assessment of clinical features in solitary minimum size (<1 cm) bladder cancer]

We retrospectively evaluated primary non-muscle-invasive bladder cancer diagnosed between 1999 and 2008 at 2 facilities (Kawasaki Municipal Hospital and Yokohama Minami Kyosai Hospital). Size (< 1 cm) solitary bladder cancer statistically evaluated the characteristics. Out of 463 bladder cancers, 52 were minimum-size solitary pTa bladder cancers less than 1 cm in diameter. The average follow-up period was 50.9 months. The recurrence rate of the minimum-size bladder cancer was significantly lower than that of bladder cancers of other sizes (1 to 3 cm or ≥ 3 cm). The 3-year non-recurrence rate was 80.7,71.0,and 62.9% in each group (< 1, 1 to 3, ≥ 3 cm). High-grade minimum size bladder cancer (pTa) showed a significantly higher recurrence rate than the low-grade cases (P = 0.0101). Intravesical chemotherapy with anti-cancer drugs significantly reduced the intravesical recurrence rate in the low-grade minimum-size bladder cancer group (P = 0.0418). There was no statistically significant difference in either the average recurrence number or the rate of multiple recurrences between the minimum-size tumor group and the 1 to 3 cm tumor group. Minimum size bladder cancer had a lower recurrence rate than tumors of other sizes; however, there were no differences in other characteristics between the groups. Therefore, sufficient treatment, in accordance with the guidelines, should be administered for minimum size tumors as well as tumors of other sizes.