Any experience good or bad with either of these labs for PCR testing. My ONC uses both and doesn't care who I prefer he sends it to? Anyone know if one lab has more sensitive PCR vs the other? Thanks in advance.
PCR Testing Lab Comparison - Quest (Atlanta) vs Genoptix (Carlsbad, CA)
Posted 20 November 2013 - 11:15 AM
I apologize if you already know this, but it is important to have one lab do all your PCR testing. It appears your onc doesn't understand this. Ideally too, your PCRs are reported using IS.
This is from an old article (2009), but the logic still rings true. I know there has been discussion about using the same lab on this forum. However, your Dr may respond better to a scholarly article.
QPCR tests for BCR-ABL suffer from a lack of standardization. Minor and major technical differences may occur from laboratory to laboratory; the use of a ratio to report the result (BCR-ABL transcript number/control gene) complicates matters because various laboratories use various control genes (hence, the denominator, and thus the ratio, change). Thus, the same sample may get different ratios at different laboratories. This is especially problematic in the United States, where many laboratories are available, laboratory use may vary as insurance contracts are changed, etc. Moreover, there are several concepts of BCR-ABL reporting that are often misunderstood. The near-mythical concept of the MMR was originally described as a 3-log reduction in BCR-ABL level from a median level of an aggregate of diagnostic samples. Thus, each laboratory's (and each clinical study's) MMR value may vary because it will be based on a different population. Thankfully, there is a movement to standardize BCR-ABL testing and reporting; a standardized International Scale has been proposed by the National Institutes of Health Consensus Group, which uses the baseline values defined in the IRIS trial to represent 100% and fixes a 3-log reduction from the standardized baseline (MMR) at 0.10%.15
Another complicated issue is the issue of a negative test. Obviously, on the surface, one would rather be negative for BCR-ABL than positive, but negative QPCR assays can result from (1) a relatively insensitive assay, (2) a degraded sample, or (3) actual disease burden below the level of detection, with an adequate sample. Only the last should be greeted with enthusiasm. The implications of a "complete molecular remission," defined by the negative QPCR in a sensitive assay, with strict controls as to RNA quality, is currently under investigation in clinical trials.
Message was edited by: Tedsey
Posted 22 November 2013 - 08:12 AM
Thanks Tedsey - yes, I am aware of the importance of using the same lab and always advise the technician to send to Quest Atl. I actually just received my first ever 0.000% in the Atl lab. If the CA lab had a better sensitivity, I wanted to test for 0.000 with them as well. Thanks.
Posted 22 November 2013 - 10:20 AM
I was consistently PCR negative with Quest, Dr switched to Genoptix and I am no longer PCR negative. I am MMR near low end of detectability. I have bounced back and forth with trying to figure out if my status changed or if it is the lab. Unfortunately at the same time they switched my drug and modified dosage, so hard to tell what caused what. I can tell you that Genoptix gets the results back much faster. One time they got it back the next day. I know when they draw for Genoptix they put it in a special envelope and send it out immediately. They did not seem to have the same immediacy with Quest. Quest seemed like it went through the regular process just like all other samples. So it is possible that Genoptix is getting a fresher sample. They may also have more sensitive equipment, although both claim to report to the same sensitivity and both are IS. I can tell you that Genoptix is owned by Novartis and they are the ones used for Novartis clinical trials.
My experience: I was happier with Quest, but if I had to guess I would say Genoptix is probably more accurate. Would love to get a sample sent to Quest just to see if they come back negative but Dr said he can't because hospital now has a contract with Genoptix for PCR testing.
Posted 22 November 2013 - 01:01 PM
My bloodwork was analyzed by Quest for my first year and I was considered PCRU for a while. Then when we switched to Labcorp, I lost my undetectable status. I don't have much faith in Quest. I don't think I was ever truly PCRU. But I'm no expert.
Posted 22 November 2013 - 05:00 PM
Happy to hear about PCRU!!!!! Well, if you are zero at both labs, then it is definitely a zero than an error or sensitivity. Keep up the good work!
Wishing you PCRU at every lab,
Posted 26 November 2013 - 02:05 AM
My Onc started sending to Genoptix just recently. He says Genoptix is International Scale calibrated, and they want to see if people achieve PCRU with Genoptix so they can be eligible to try stopping their TKI. Truth is, unless you are considering stopping treatment, where the data is based on IS results, it probably does not matter what lab you use. At low levels of disease all you really need to see is which way the number is trending (hopefully down or staying at PCRU).
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