FISH Test Reliability

Has anyone experience with FISH cytologies? I was diagnosed with T1, High Grade bladder cancer about five years ago. I have had a number of TURBTs followed by BCG regimens – usually a series of six a month apart. After my last BCG series my FISH test came back positive but a radiological examination of my kidneys and ureters was normal and my cystoscopy was clear. My URO was at a loss to explain the results and decided doing nothing was not the thing to do so he put me on monthly BCGs for a year (I do #11 this coming week). My question is: “Are FISH tests - besides being very expensive - reliable?”

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FISH (fluorescence in situ hybridization) is quite "reliable", however there is no medical test that is without false negatives and positives. One paper I have read indicates inflammation as an issue with false positive urine FISH. Some look at FISH as so sensitive that a positive may precede the ability to detect a new tumor, but how can one know if this is a true predictor or just a coincidence? Usually, urine cytology is quite good for high grade lesions. I would think it reasonable to consider all the data, routine urine cytology, FISH, and cystoscopy when deciding upon a course of treatment.

jj

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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.

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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.

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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.

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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...

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Hi,

I looked through what is in the urotoday data base on FISH and could not find a correlation with stage. One of the studies did find that FISH was more sensitive (that is more positive tests) for higher grade than lower grade lesions. Urine cytology seemed to be more specific(positive test actually represents bc) than FISH in all studies. Did see one study that looked at using FISH to predict progression. It was better than chance, but the number of patients in this study was incredibly small. If I were having FISH testing, I would use it as someone's doctor stated, as a yellow light. Should be followed up with cystoscopy and if concurrent urinary cytology was not done with urine cytology. I have no personal experience with urine FISH so only base this opinion on very limited information. Urologic oncologists who routinely use this have much more experience in interpreting the results and recommending follow up.

jj

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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

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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...

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