In Ta bladder cancer, the share of high-grade tumour tracked with progression

Design

Retrospective cohort with central pathology review

Population

321 patients with primary high-grade pTa urothelial carcinoma, Canada

Primary outcome

Recurrence-free and progression-free survival by high-grade proportion

Effect

No link with recurrence; worse PFS at ≥10% high-grade thresholds; 5% did not discriminate

This Canadian retrospective cohort included 321 patients with primary high-grade pTa urothelial carcinoma, all with central genitourinary pathology review to quantify the high-grade proportion. Median follow-up was 61 months; recurrence occurred in 35.5% and progression to T1 or higher in 9.4%.

The proportion of high-grade tumour was not associated with recurrence after adjustment; age and multiplicity were. But progression-free survival worsened stepwise at high-grade thresholds of 10%, 25%, 50% and 100%. The current WHO cut-off of 5% did not separate outcomes. The effect was most marked in exploratory subgroups not given BCG.

A tumour labelled high grade on the basis of a small focus may behave differently from one that is mostly high grade. Asking pathology to report the percentage helps refine counselling and the intensity of surveillance, though it should not yet override guideline risk groups.

• Ask pathology to report the approximate percentage of high-grade tumour in Ta lesions
• Consider closer surveillance for Ta tumours that are largely high grade
• Continue to manage high-grade Ta per guideline risk groups, including BCG where indicated
• Record multiplicity and age, which predicted recurrence in this cohort

Why it matters

The binary 'high-grade' label may hide a range of risk that matters for surveillance.

Don't overread it

Retrospective, with several thresholds tested; it does not change guideline risk categories.

The statistics, in plain English

Progression occurred in fewer than 1 in 10 patients, so estimates at each threshold rest on small numbers. Testing several cut-offs increases the chance of a spurious finding, which is why the authors call for prospective confirmation.

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