Correspondence to: Thomas A. Stamey, M.D., Department of Urology S-287, Stanford University School of Medicine, Stanford, CA 943055118 (e-mail: tstamey{at}stanford.edu).
A recent report in the Journal (1) reported on the first two rounds of population-based screening at intervals of 4 years in the European Randomized Study of Screening for Prostate Cancer. A total of 4133 men aged 5575 years were screened in the first round, and 2385 of these men were screened in the second round, 4 years later. Sextant biopsy specimens were obtained under ultrasound guidance during both rounds of screening, with all cores embedded separately; the total amount of cancer in needle biopsy sets and the percentage of adenocarcinomas of Gleason score 7 or higher were calculated.
The main result of Hoedemaeker et al. (1) was that the second round of screening found less cancer (median of 4.1 versus 7 mm in the biopsies) and fewer cancers of Gleason score 7 or higher (median of 16% versus 36%) than the first round of screening. On the basis of these data, the authors assume that the cancers were smaller in the second round of screening than in the first round.
However, the U.S. literature is replete with evidence that the amount of cancer found in sextant biopsies of the prostate [such as the sextant biopsies of Hoedemaeker et al. (1)] is unrelated to the volume or grade of the largest (index) cancer in the prostate as determined by radical prostatectomy. For example, a recent study from my group (2) shows the absence of any relationship between the index (largest) cancer volume in 222 radical prostatectomy specimens and the number of positive sextant biopsies, the total length of cancer in the biopsies, and the percentage of cancers with Gleason grade 4/5 in sextant biopsies (Fig. 1). In this study, all 222 biopsies were reviewed by the same expert pathologist who later determined the index (largest) cancer volume from 3-mm step-sections, a protocol we have used at Stanford since 1983 in over 2000 consecutive prostates. All biopsy results were determined long before the prostate specimen was reconstructed. As Fig. 1
shows, the Pearson correlations are much too low to be of any practical or theoretical use. More important, the vertical spread of index cancer volume is so wide at any given value for the three volume-related measurements in the biopsies that the relationship between the results of sextant biopsies and the size of the largest cancer in the prostate is meaningless. Because these biopsy parameters are essentially the same as those measured by Hoedemaeker et al. (1), the authors should look for reasons other than a reduction in cancer volume as the cause of the differences in positive biopsy rates between the first and second screens.
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REFERENCES
1
Hoedemaeker RF, van der Kwast TH, Boer R, de Koning HJ, Roobol M, Vis AN, et al. Pathologic features of prostate cancer found at population-based screening with a four-year interval. J Natl Cancer Inst 2001;93:11538.
2 Noguchi M, Stamey TA, McNeal JE, Yemoto CM. Relationship between systematic biopsies and histological features of 222 radical prostatectomy specimens: lack of prediction of tumor significance for men with nonpalpable prostate cancer. J Urol 2001;166:10410.[Medline]
3 Wise AM, Stamey TA, McNeal JE, Clayton JL. Morphologic and clinical significance of multifocal prostate cancers in radical prostatectomy specimens. Urology. In press 2002.
4 Dietrick DD, McNeal JE, Stamey TA. Core cancer length in ultrasound-guided systematic sextant biopsies: a preoperative evaluation of prostate cancer volume. Urology 1995;45:98792.[Medline]
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