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SAN FRANCISCO -- Adding urine tests to standard cytoscopy for surveillance after non-muscle invasive bladder cancer may increase cost without boosting detection, according to a prospective cost-effectiveness study.

Cytoscopy alone detected 52% of bladder tumors with a cost of $7,692 per cancer detected, Jose A. Karam, MD, of the University of Texas M.D. Anderson Cancer Center in Houston, and colleagues reported at Genitourinary Cancers Symposium here.

The most sensitive combination, cytoscopy plus a FISH-based urine test that caught 72% of bladder cancers, was also the least cost-effective at $19,111 per detected cancer, Karam said at a press conference.

The additional tumors detected by FISH and others were noninvasive and early stage.

Delaying those tumors three or four months until the next screen, when all the screening modalities caught them, wouldn't impact survival, whereas earlier detection of invasive tumors might, he said.

"These results suggest we should be using these markers carefully and judiciously when surveying patients with bladder cancer," Karam told reporters.

Press conference moderator Nicholas J. Vogelzang, MD, medical director of the Developmental Therapeutics Committee of US Oncology, called the findings helpful but expressed chagrin, since he was one of the developers of the NMP22 urine test.

Cost is key because the lifelong surveillance needed to catch recurrence -- 60% in the most common non-muscle-invasive type -- adds up to make bladder cancer the most expensive tumor in the U.S., Karam said.

Many biomarkers for recurrence have been developed into urine tests, but these are expensive and yield many false positives, he noted.

Cost-effectiveness had not been prospectively evaluated, so Karam's group compared the cost and detection of four clinically-used strategies: cytoscopy alone or in combination with NMP22, FISH, or cytology. They added a fifth "hypothetical" arm of cytoscopy plus positive NMP22, confirmed by positive FISH.

Among 200 patients with a history of bladder cancer included in the prospective study, baseline screening picked up 13 true positive cancers with each strategy.

False positives were lowest with cytoscopy alone (two) followed by the hypothetical triple screen test (six) and cytoscopy plus cytology (14), NMP22 (19), and FISH (30).

"Because we didn't act on all these false positives, we made the assumption that if these were real positives, we would be able to detect them at the first follow-up," Karam explained at the press conference.

At the first follow-up three to four months later, neither of cytoscopy's false positives were confirmed to be correct. The addition of FISH had the highest predictive value, with five tumors correctly predicted. But it still had the highest number of incorrectly predicted tumors (25), too.

Among those initially thought to be false positives, follow-up showed these to have been correctly predicted in one case for cytoscopy plus NMP22, two for cytoscopy plus cytology, and one for the cytoscopy, NMP22, and FISH combination.

Thus cost per cancer detected, including tumors found at first follow-up, was:

• $7,692 for cytoscopy alone: total cost $100,000, detection rate 52%
• $11,143 for cytoscopy plus NMP22: total cost $156,000, detection rate 56%
• $19,111 for cytoscopy plus FISH: total cost $344,000, detection rate 72%
• $10,267 for cytoscopy plus cytology: total cost $154,000, detection rate 60%
• $9,557 for the combination of cytoscopy, NMP22, then FISH: total cost $133,800, detection rate 56%

Karam cautioned that the improvement in detection from 52% with cytoscopy alone to 72% with the addition of FISH "was due to detection of, again, early stage and noninvasive tumors."

He said that a multicenter prospective study is planned to further validate these results "before we can recommend a change in clinical practice."

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