Non-muscle-invasive bladder tumors 15 mm or less in diameter are associated with a lower risk of recurrence after surgical treatment compared with larger tumors, according to researchers.
In addition, their study of 768 patients who underwent transurethral resection for non-muscle invasive bladder cancer (Ta/T1) showed that differentiating tumors into three size categories can provide additional information in predicting recurrence.
Investigators at University Hospital, Linköping, Sweden, led by Georg Jancke, MD, categorized tumors according to five sizes (1-10, 11-20, 21-30, 31-40, and greater than 40 mm in diameter) or three sizes (1-15, 16-30, and greater than 30 mm in diameter).
Of the 768 patients, recurrence occurred in 478 (62%) and progression occurred in 71 (9%). In the five-size group, tumors 21-30 mm in diameter were associated with a significant 57% increased risk of recurrence compared with tumors 1-10 mm in diameter, after adjusting for multiple variables, Dr. Jancke and colleagues reported in the Scandinavian Journal of Urology and Nephrology (2011;45:388-392). Tumors 31-40 and greater than 40 mm were associated with a significant 2.2 and 2.7 times increased risk of recurrence, respectively. In the three-size group, tumors 16-30 mm and greater than 30 mm in diameter were associated with a significant 42% and 2.4 times increased risk of recurrence compared with tumors 1-15 mm in diameter. Tumor size was not associated with progression.
The researchers recommend the three-size over the five-size model “because it is preferable from a statistical point of view due to the lower degrees of freedom,” Dr. Jancke said. In addition, they measured tumor size using the diameter of the resection loop, which was 7 mm. This measurement method is easier to use for the three-size model, the researchers noted.