Low-risk bladder cancer patients with tumors smaller than 1 cm could be classified separately as a “very-low-risk” group, according to a new analysis. These patients tend to be younger and have low recurrence risk; the recurrences that are seen tend to arise beyond the recommended 5-year surveillance period.
Patients who are diagnosed with non–muscle-invasive urothelial carcinomas are generally stratified into low-, intermediate-, and high-risk groups. Low-risk patients include those with primary, solitary, Ta, low-grade tumors smaller than 3 cm not accompanied by carcinoma in situ. The 5-year probability rate of recurrence in these patients is 31%, and the 5-year risk of progression is 0.8%.
“Tumor size is a known prognostic factor in low-grade bladder tumors, but the ‘low-risk’ category embraces a rather wide range of dimensions from 0 to 3 cm,” wrote study authors led by Ofer N. Gofrit, MD, PhD, of Hadassah Hebrew University Hospital in Jerusalem, Israel. They looked into the homogeneity of the low-risk classification in a group of 211 patients included in a prospectively maintained database.
The cohort had a mean age of 66.7 years, and included 43 women and 168 men. All patients underwent transurethral resection between 1998 and 2008, and all had negative urinary cytology and negative upper tract evaluation. The results were published in BJU International.
The patients were followed for a median of 10 years. Sixty-five patients experienced a recurrence (30.7%), after a median of 3.15 years. On a multivariate analysis, only tumor size was a significant predictor of recurrence; 19% of those with a tumor of 1 cm or smaller had a recurrence, compared with 38.6% of those with tumors over 1 cm in size (P = .008).
Five patients had progression to high-grade disease, which was accompanied by stage progression in three patients. All three patients had primary tumors larger than 1 cm.
In total, 40% of the cohort had tumors of 1 cm or smaller. Patients with these smaller primary tumors were younger (64.6 years vs 68.3 years), and they were more likely to be asymptomatic at presentation (P = .047). The 5-year recurrence-free survival rate was 92% in those with smaller tumors, compared with 70% in those with larger tumors (P = .0009).
The median time to recurrence was 3.6 years in patients with larger tumors, which was significantly shorter than the 5.7 years in those with tumors 1 cm or smaller (P = .03). Of the recurrences that did arise in patients with smaller tumors, only 43.7% occurred within 5 years; 75.5% of the recurrences in those with larger tumors occurred within that time frame.
“In most guidelines the recommended follow-up in cases of low-risk bladder cancer includes periodic cystoscopies for 5 years,” the authors wrote. The new data, they added, “suggest that ‘low-risk’ bladder cancer is not a homogenous group and is composed of two distinct populations.” Tumors they dubbed “very-low-risk” are at a lower risk of recurrence but may have recurrences that are delayed beyond those 5 years.