More on [11C]choline PET/CT scanning in men with recurrent prostate cancer

A new article just published on line in the Journal of Urology offers additional information about the “operational characteristics” of [11C]choline PET/CT scanning in the diagnosis of biochemically recurrent prostate cancer after first-line treatment (a technique currently available only at the Mayo Clinic in Rochester, MN).

According to this article by Mitchell et al., based on a retrospective review of data from all 176 patients with recurrent disease who underwent [11C]choline PET/CT scanning at the Mayo Clinic between  September 2007 and November 2010:

  • 56/176 men (32 percent) had clinically useful [11C]choline PET/CT scans (implying that the scans were able to define prostate cancer lesions that were not identifiable with conventional forms of imaging and that lead to changes in the patients’ clinical management)
  • The optimal value of a patient’s PSA at the time of lesion detection was 2.0 ng/ml.
  • Two data points were significant predictors of a positive [11C]choline PET/CT scan result:
    • The patient’s PSA at the time of the PET/CT scan (hazard ratio [HR] = 1.37; p = 0.04)
    • The patient’s clinical stage at the time of his initial diagnosis of prostate cancer (HR = 5.19; p = 0.0035)
  • A patient-based analysis of [11C]choline PET/CT data showed that this scan had
    • A sensitivity of 93 percent
    • A specificity of 76 percent
    • A positive predictive value (PPV) of 91 percent
    • A negative predictive value (NPV) of 81 percent

The authors conclude that [11C]choline PET/CT scanning “performs well” as an imaging test to identify the presence of prostate cancer lesions in men with biochemical recurrence following primary treatment failure.

10 Responses

  1. This is of little clinical value for most patients with and physicians treating metastatic prostate cancer.

    First of all, choline PET/CT was of no value in 68% of the patients studied.

    Even though a “change in management” occurred in 32% of patients, did this result in any improvement in quality of life or survival? If not, this study is useless if not detrimental to any effort to curtail the constant release of industry-sponsored technology from getting to the medical marketplace only to create unjustified hype and raise health care costs.

  2. Dear Dr. Kelly:

    First, I would absolutely agree with you that a choline-C11 PET/CT scan is a pretty pointless test for someone with evident metastatic disease. Why would one want this test if such mets are visible on a bone scan or a CT scan?

    However, I would argue that there is a considerable potential value to this test for some patients with a rising PSA after first-line therapy but no clear evidence of whether this is a localized or micrometastatic recurrence. If the recurrence is local, it may be effectively treated with localized radiation therapy alone. If the recurrence is distant, then radiation therapy may be pointless.

    With regard to the cost issue, there are certainly numerous issues, and as a society we need to start to resolve these. However, I would (gently) point out that this particular test has been developed by a not-for-profit medical institution, not by “industry”. The question of whether it is or is not covered by a specific insurance provider is a separate issue, as is whether or not it is “worth it” to an individual patient to fly to Rochester, MN to have a test like this carried out.

    You may well, rightly, determine that this test is of no value to you or to many of your patients. Others may make a different decision. The “New” Prostate Cancer InfoLink is merely the messenger.

  3. For me, this is an extraordinarily timely discussion. My PSA is low but rising rapidly, and my cancer is still ADT-responsive. I recently underwent a carbon-11 scan, but it was [11C]acetate at AMIC, rather than [11C]choline at the Mayo Clinic. It failed to turn up any bone mets, and identified one suspicious lymph node.

    If the cancer cells in the lymph node are the primary (or sole!) source of my PSA rise, and if I can blast them to kingdom come with tightly focused SBRT, then I may be able to postpone resumption of ADT for years, possibly longer.

    As I’ve said before, the term “metastatic” (or, more properly “evidently metastatic”) is a moving target. Before the advent of extremely advanced imaging, my cancer would have beeen considered non-metastatic, but with better technology, the same cancer is reclassified as metastatic, despite the unchanged histopathology. As this happens with more and more frequency, such imaging becomes more and more useful in allowing men to choose less-damaging treatments with some confidence.

  4. I totally agree with Mike and PaulC. My husband’s PSA is rising, after 2 years of ADT and EBRT. He experienced very significant cognitive issues resulting from the ADT and, at present, says he’ll refuse to go back on it. Having a tool like the one developed at Mayo, which could determine if the prostate cancer is local or distant, is a blessed gift, one we will be asking for if the PSA continues to rise.

  5. I know of two cases in which a C-11 acetate PET/CT done here in Arizona by the Arizona Molecular Imaging Center was able to find diseased lymph nodes in these patients and then they were further treated with targeted radiation. This is a recent event (within the last 5 months) and one of the men reported a reduction in PSA. I have not communicated with the other as he is traveling.

    Radiation of lymph nodes in metastatic prostate cancer in patients who are progressing even when on ADT is a potential way to slow down the disease. … In my view, with few side effects, this is progress.

  6. Considering the desperate need for better scanning options for prostate cancer, I don’t think we should disparage the efforts of Dr. Kwon and his colleagues. While C11 might only be usable for a small segment of prostate cancer cases, in those it can often lead to curative treatments after failed primary and secondary attempts. And one of these days, efforts such as this might finally result in a scan that can detect the cancer at a much earlier stage.

  7. Maybe it is just me, or maybe it is just this day but the question seems backward to me.

    Maybe the time for a C11 test is not after initial treatment. The better question is how many recurrent cases would have been avoided by a C11 prior to initial treatment.

    As Sitemaster points out, there is considerable savings in $ and life in knowing, even if in only an additional 32% of cases, that the micrometastatic recurrence is distant.

    Is it a recurrence at all, or just newly visable? Logic says the cancer must have already spread before treatment. PaulC nails it.

  8. Michael:

    There may well be a small number of men who would benefit from an [11C]choline PET/CT scan prior to any therapy. The problem, however, is that:

    (a) We have no good way to identify which men are at such risk.

    (b) There is currently only one center in the world that can do this test (and the [11C]acetate test is not thought to be as accurate).

    (c) The [11C]choline PET/CT scan has only been tested and approved by the FDA for use in men with recurrent disease (so we don’t actually know how accurate it would be if used in men prior to any therapy).

    (d) It already has a degree of in-built inaccuracy (false positives and false negatives) in men with recurrent disease; such inaccuracies could well be significantly higher in newly diagnosed and untreated patients — which would not be good.

    All this theorizing would be wonderful if the [11C]choline PET/CT scan (or the comparable acetate scan) was 100% accurate … but it isn’t; and it would have to be appropriately tested in a well-characterized set of untreated patients before we would really know whether it had utility in such men.

  9. I agree, there is no current data to show enhanced testing (of any kind) prior to treatment would be of benefit. We will not know until it is actually tried, granted, we may not know then either.

    False positives and false negatives are of course a large problem. We currently operate under a system which already has at its core the “art” of biopsy reading. This is commonly followed with treatments, which do not necessarily stand up to objective standards. Unnecessary treatment is easy to see in the aggregate, much harder at the individual case level.

    Much cutting edge research, in the end, does not cut it. But then many current treatments are full of unknowns as well. Is there risk in bringing advanced treatments/tests to the pre-treatment stage? Yes. But we need to compare that risk to the results/risks of the current protocols/real world practices.

    In the cold-hearted sense, does a test (any test) which better screens a majority prior to treatment have more value then, than when used to make finer distinctions between those who have already entered the truly high risk stage? I do not see it as need to choose, I see it as a possibility for both groups.

  10. It should be pointed out that radiation may not be the only option if one or two lymph nodes light up on a choline scan; the removal of a few lymph nodes would be an option as well, and this is actually done at the Mayo Clinic in specific cases. There is no guarantee that this will put the cancer in year(s)-long remission, but any delay in recurrence by a number of months or years is certainly welcome for some patients.

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