Citrate concentrations in seminal fluid and risk for prostate cancer

Another paper to be presented as a late-breaking poster at the upcoming annual meeting of the American Urological Association in San Diego suggests that citrate concentrations in seminal fluid may be a more accurate marker for prostate cancer risk than PSA levels.

Gregório et al. (Late-Breaking Science & Technology Posters; abstract no. LB-S&T-29) studied the citrate concentrations in the seminal fluid of 32 consecutive patients with a histological diagnosis of clinically localized prostate cancer. Citrate concentrations were measured using high-resolution nuclear magnetic resonance spectroscopy (1HNMRS). They also measured citrate concentration levels in a control group of 32 men under long-term follow-up (mean of 4.64 ± 2.88 years) for benign prostate hyperplasia (BPH), all of whom had elevated PSA levels (> 4 ng/ml) and several prostate biopsies negative for cancer (mean of 2.61 ± 1.38 biopsies per control).

Here are their findings:

  • The average (median) citrate concentration was significantly lower among the patients with prostate cancer (at (4.76 mM/l) than it was among to  controls (at 13.74 mM/l).
  • There was no significant difference in the average (median) PSA levels between patients (at 7.94 ng/ml) and controls (at 8.25 ng/ml).
  • The accuracy (specificity?) of citrate concentrations for detecting prostate cancer (at 73.1 percent) was significantly superior to that of a PSA level (at 53.4 percent).

Giving a seminal fluid sample requires masturbation and ejaculation, and so it is a somewhat less convenient method for obtaining a specimen than giving a blood sample for a PSA test.

A test like this would need re-validation in a separate and larger group of patients before we could consider it as a test for risk of prostate cancer … regardless of the issues related to sample collection.

3 Responses

  1. Isn’t the study referring referring to citrate concentrations determined with MRI spectroscopy? If so, it would simply be another sequence (set of pictures and data) done during a mutliparametric MRI.

  2. Dear Mark:

    No. It is referring to a technique called nuclear magnetic resonance (NMR) which is a purely laboratory technique more like mass spectrometry.

  3. The two are similar in the way they detect molecules — both use nuclear magnetic resonance, one in vivo, the other in vitro. In fact, MRI spectroscopy has been used to detect citrate concentrations as an indicator of high grade prostate cancer. What they look for is elevation in choline levels relative to a reduction in citrate levels. (They add creatine to choline because they are indistinguishable.) Some have argued that this ought to be one of the parameters in a multiparametric MRI, but adding it to the other three parameters (T2, DCE, and DWI) doesn’t seem to improve detection.

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