According to the researchers, about 40% of patients with low-risk bladder cancer can be put into a "very-low-risk" category characterized by younger patient age, smaller tumors, and a lower recurrence rate than patients with larger tumors. The findings are published in the BJU International (formerly the British Journal of Urology).

Analysis of data from a series of 211 low-risk bladder cancer cases shows that in patients with tumors with a diameter of ≤1 cm, most recurrences took place after the recommended 5-year surveillance period and can thus be described as very low risk, say Ofer N. Gofrit, et al. from the Department of Urology at Hadassah Hebrew University Hospital.

The median time to recurrence was 5.7 years in patients with tumors 1 cm or less compared with 3.6 years in patients with tumors 1.1-3.0 cm in diameter, highlighting the need for longer follow-up in patients with smaller tumors, the study authors emphasize.

At present, patients diagnosed with low-risk non–muscle-invasive urothelial carcinomas have primary, solitary, low-grade tumors smaller than 3 cm with no evidence of carcinoma in situ, the investigators note. The 5-year risk for progression for these low-risk tumors is 0.8%.

"Taken together, it seems that these patients [with tumors ≤1 cm] can be classified separately to a 'very-low-risk' group," the study authors suggest. Cystoscopy at 3 months after resection followed by annual ultrasound evaluation for 10 years "is a reasonable surveillance protocol," they add.

Notably, only 43.7% of recurrences happened within the first 5 years in patients with tumors ≤1 cm. More than half of recurrences in this group were spread out over the remaining 10-year period. By comparison, 75.5% of recurrences in patients with larger tumors took place in the first 5 years after surgery.

Patients with smaller tumors were also significantly younger than those with larger tumors and were more likely to be asymptomatic at presentation. They had a 5-year recurrence-free survival rate of 92%, compared with 70% in those with larger tumors. Recurrence in this "very-low-risk" subgroup probably represents a new event of carcinogenesis, Dr. Gofrit et al. mention.

Patients with larger, low-risk tumors "can be termed 'new-low-risk' or just 'low-risk' exactly as in prostate cancer," they suggest. For this group, "the current guidelines seem very appropriate."

Alexander Kutikov, chief of the Division of Urologic Oncology, said there is "compelling established evidence that once a bladder tumor develops, recurrence risks exist indefinitely."

After a diagnosis of bladder cancer, "most urologic oncologists monitor young patients’ long-term, regardless of primary tumor size," he mentioned. "These data support this practice, since a nontrivial number of patients exhibit recurrence and grade/stage progression."

Dr. Kutikov noted that guideline panels "struggle to balance the persistent risks of recurrence against the burden of indefinite surveillance and its costs."

Looking ahead, he predicted that genomic risk stratification in bladder cancer will change the way clinicians approach surveillance. "This space remains ripe for disruption with improved risk stratification," Dr. Kutikov said.

He emphasized that "cystoscopic evaluation and upper tract imaging is the standard of care surveillance strategy for patients with urothelial carcinoma."