Prostate cancer news reports: Saturday, April 3, 2010

Today’s news reports deal with such items as:

  • The effects of antiretroviral drugs for HIV/AIDS on the XMRV virus
  • Diet, milk, and prostate cancer etiology
  • Can saturation biopsies really identify low-risk cancers?
  • Prostate weight and prostate cancer recurrence

There’s been a good deal of media noise about an article by Singh et al. in PLoS ONE. The authors report that several inhibitors of the HIV/AIDS virus appear to be active against the XMRV virus too (when used alone or in combination). This is interesting but is of minimal clinical significance in prostate cancer (yet). There is still no definitive evidence that XMRV has the ability to increase risk for (let alone cause) prostate cancer. All we know today is that the XMRV virus can often found in men who have prostate cancer. There is a nice, non-scientific summary of this paper on the Scientific American web site.

A small Canadian study by Raimondi et al. looked at the effects of some 200 foodstuffs on risk for prostate cancer using a case-control method. They concluded that their results support “the hypothesis that dairy products, especially milk, are involved in the etiology of prostate cancer.” They go on to note, however, that “the mechanisms by which the various nutrients in dairy products and total diet may interact to influence this risk remain unknown.”

Pepe et al. have provided further evidence that saturation biopsies are somewhat less than reliable as predictors of low-risk or indolent prostate cancer. They compiled  a series of 413 patients who were given saturation biopsies at their institution between 2005 and 2008 (with a median of 30 cores). A single  microfocus of prostate cancer (5 percent or less in a single core) was found in 55/413 patients, all of whom went on to have an open radical prostatectomy (RP). The median PSA level for these 55 patients was 8.2 ng/ml at diagnosis, their DREs were all negative, and the Gleason score was 6 in 40 cases and not evaluable in 15 cases. After RP, there was evident and significant prostate cancer in 48/55 patients (87.3 percent) with a median Gleason score of 6.2 (range, 5-8), extraprostatic extension in 15/55 patients (27.3 percent), and positive surgical margins in 8/55 patients (14.5 percent). Only 6/55 patients (10.9 percent) had truly indolent prostate cancer, and in 1 patient no tumor was found at all. In other words, only 7/55 patients (12.7 percent) with a single small microfocus on saturation biopsy actually had truly indolent disease.

Earlier studies have suggested that man with low prostate weight may be at lower risk for prostate cancer recurrence than those with heavier prostates. However, in a careful pathological study of 431 surgically removed prostates, Davidson et al. have shown that, “Although increasing prostate weight correlates with increased patient age and higher preoperative PSA level, it does not independently predict postoperative cancer recurrence.” At least for once, apparently, size does not matter!

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