FISH Test Reliability

• By rrmc
• Reply 1972806
• February 14, 2011 at 9:01 am
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I had a false positive FISH about a year ago; the uro initially thought I was a failed BCG, but after a negative TUR, he stated the positive was most likely the result of BCG inflamation. Subsequent three month cystos and FISH have been negative. I just graduated to 4 month cystos and BCG.

• By PaulR
• Reply 1973392
• February 14, 2011 at 12:36 pm
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I've had a lot of postive FISH tests when there was no other confirmation except maybe an "atypical" cytology result. In every such case I can think of, the confirmation came later from either a positive biopsy, positive cytology, or "suspicious" cytology. It certainly is possible to have a false FISH positive, but the frequency of false cytology negatives is much higher. In short, I would have more confidence in a FISH positive than a cytology negative. Unfortunately, few if any doctors will treat solely on the evidence of an isolated FISH positive, so the test serves mainly as an early warning indication. My oncologist says he considers an isolated FISH positive as a "yellow-light" warning that all may not be well. I.e., he uses it as a signal to do check-ups at more frequent intervals. In my case it was every 3 months until either a positive or suspicious cytology or biopsy occurred, and then treatment was begun.

• By midwestone
• Reply 1973595
• February 14, 2011 at 2:05 pm
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My urologist and I came to the conclusion that my "brand" of cancer was not detectable by FISH test. So the Negative FISH I had was a false negative. That's a dangerous test result, leading to complacency. Do not rely on FISH.

• By Whinny2
• Reply 1974252
• February 14, 2011 at 7:34 pm
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So far I have had two negative FISH tests about a year apart while I've been on BCG maintenance treatment following the intial TURBT and BCG induction for a TaGrade3 BC. I am grateful for the negative FISH tests but have read something that said the FISH test is more reliable for more advanced BC and less reliable for less advanced BC. PErhaps jj can confirm or refute this...

• By NL
• Reply 1974925
• February 15, 2011 at 6:18 am
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FISH was not a reliable test for me. I had several and each time they came back negative but when I had biopsies done, cancer was present. I had a urologist tell me one time immediately prior to surgery to remove several spots and do biopsies that I had good news - the FISH test was negative. When I got the lab results of the biopsies, I still had non-invasive, Grade 3 cancer. It was a waste of money for to have the test FOR ME...wouldn't say that it is the same for others...just for me.
Nancy in VA

• By robin5
• Reply 1974990
• February 15, 2011 at 7:26 am
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My husband had BCG for 2 years after his diagnosis. At his first appointment 6 months post BCG treatments, he had some cancer cells in the urine but everything looked okay. The doctor ordered the fish test and it was positive. He said to wait. A repeat fish about 4 months later was also positive. He did a cysto and looked at ureters, and everything else and then the turb showed prostatic urethral involvement even though the bladder didn't look bad. he recommended RC asap. At that point, we went to Sloan where after another TURBT, doctors agreed that RC is necessary (having it 3/4). I shouldn't second guess our decisions, but should have gone for the other opinions after first fish test. Dr Herr at Sloan, our doctor now, didn't seem to think the time extension mattered, though, or else he was being tactful. So for us, the fish was the first indication of a problem...