Who really needs a bone scan at time of diagnosis?

Every year tens of thousands of men newly diagnosed with prostate cancer are given a bone scan (and other types of scan) as part of their “normal” diagnostic work-up. The only value of the bone scan is that it is able to identify men who already have (or at least may have evidence suggesting) actual metastatic prostate cancer to their bones at the time of diagnosis.

At least two major sets of guidelines today state clearly that bone scans are not necessary in men diagnosed with low- and intermediate-risk prostate cancer:

  • According to the guidelines of the National Comprehensive Cancer Network (NCCN), bone scans should be limited to men who have a life expectancy of > 5 years and who have
    • Clinical stage T1 disease and a PSA > 20 ng/ml or a Gleason score of ≥ 8 (or both)
    • Clinical stage T2 disease and a PSA > 10 ng/ml or a Gleason score of ≥ 8 (or both)
    • Clinical stage T3 or T4 disease regardless of PSA or Gleason score
  • According to the guidelines issued by the European Association of Urology (EAU), bone scans “may not be indicated in asymptomatic patients” if the PSA level is < 20 ng/ml and the Gleason score is < 8.

Guidance documents available from the National Cancer Institute and the American Urology Association offer no specific commentary on the appropriate use of bone scans as part of the work-up of the newly diagnosed prostate cancer patient.

McArthur et al. have just reported data from a cohort of > 800 patients in whom they sought to ensure the feasibility of implementing the current EAU guidelines (which, to all practical intents and purposes, are precisely the same as the NCCN guidelines on this issue).

Their data are based on newly diagnosed patients identified between March 2005 and January 2010, all of whom received a staging bone scan. However, patients were not eligible for inclusion in the analysis if no Gleason score was available or if their most recent PSA test was taken > 3 months prior to the bone scan.

Here are the findings:

  • The entire database included 819 patients, of whom 633 were assessed retrospectively and 186 prospectively.
  • 672/819 patients met all the inclusion criteria.
  • The average (median) age of the eligible patients was  71 years (range, 39 to 93 years).
  • 54/672 eligible patients (8 percent) had evidence of metastasis to bone based on their bone scans.
  • PSA levels and Gleason scores were both independent predictors of a positive bone scan, and their predictive value was additive.
  • 357/672 patients had a PSA level < 20 ng/ml and a Gleason score < 8 and none of these patients had a positive bone scan.

McArthur et al. very reasonably conclude that a bone scan “can be safely omitted” from the work-up of newly diagnosed prostate cancer patients with a PSA level < 20 ng/ml and a Gleason score < 8.

Of course, legal advisers to the average American urologist might well continue to suggest that a bone scan was a good idea for many men who do in fact meet the criteria specified above. It is the exception that proves the rule, and it is certainly the case that bone metastasis has very occasionally been identified in men with a PSA < 20 ng/ml and a Gleason score of < 8. However, this has less to do with good medical practice and much more to do with protecting the urologist against “malpractice” under such circumstances (which isn’t really malpractice at all).

6 Responses

  1. Thanks Sitemaster for this article which provides data supporting the guidelines.

    We need to exterminate malpractice suits for the very few exceptions to the rule. Docs should not be penalized for practicing sound medicine which is also cost effective, and we should not have to pay higher fees to cover more expensive malpractice insurance due to such predatory legal practice.

    Some of those exceptions will be in the very rare and extremely aggressive prostate cancers such as those caused by small cell prostate cancer. I’m wondering how much value a bone scan would have added, if any, in those cases.

    Some exceptions will be in men for whom other indicators will shortly suggest the need for a bone scan. It’s likely that little advantage will have been lost through the short delay in the scan.

    These considerations mean it’s likely that very few exceptions will involve true case impact due to the delay, as I see it.

  2. Confusing

  3. Allan: Think of it this way.

    There is really no good reason for a bone scan if your PSA is < 20 ng/ml and your Gleason score is < 8 because your chances of a positive result are extremely low.

    On the other hand, if you are the kind of guy who normally wears a belt and suspenders … then maybe you would be more comfortable if you had one — even though the result is still likely to be negative.

  4. In March 2008 at the age of 51 and with a PSA of 3.2, I was diagnosed with prostate cancer: 3 biopsy cores involved, Gleason 7, 7, and 6. A bone scan showed evidence of metastatic disease, bone biopsy confirmed it. So this report, if followed, would have led to a more horrible outcome and a much shorter life expectancy. Standard protocol at the time was a bone scan following a positive prostate cancer diagnosis. Thank goodness I am in Boston at Dana Farber Cancer Institute — where they do things right.

  5. Dear Bruce:

    Actually the standard guideline in 2008 would not have been to give you a bone scan based on the data you have provided if your clinical stage was T1/T2. However, it is very important to appreciate that there may still have been good reasons to give you one. You don’t mention your clinical stage at diagnosis, but if it was suspected of being T3 or T4, it would have been appropriate to give you a bone scan, and there are many other possible reasons to consider that a bone scan might be appropriate in a small subset of men with a low PSA and a Gleason score of 7.

    There are exceptions to all guidelines, but you cannot assume that you necessarily were an exception. Next time you see your physicians at Dana Farber, you might like to ask them exactly why they thought giving you a bone scan might be a good idea. Obviously, in your case, it was the right idea. And guidelines are just that — guidelines. They are not “rules,” and they do not substitute for the professional judgment of good clinicians in making decisions about individual patients.

  6. Dear Sitemaster,

    My stage at diagnosis was T2b. I respect your detailed reply and appreciate the “odds” that go into making decisions about testing. I understand that I am the exception to the rule (current staging with normal PSA) but I maintain that every test available should be used — as the cliche goes — if one person is saved then it was worth it. Their families (as do mine) are thankful each day. There were no indications that a bone scan should have been performed, no family history, 100% excellent health, etc. Plainly the health care providers here covered ALL the bases. It’s a shame that some men don’t and won’t get that same consideration.

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