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Prostate Cancer Risk Groups and Comparisons: Fruitless or Fruitful?

Sarah Cannon Cancer Center, Nashville, TN

To the Editor:I am pleased to see additional prostate-specific antigen (PSA)–based data on the outcome of men with prostate cancer treated with radical prostatectomy, as presented by Cross et al.¹ This allows us to embark on the sometimes perilous path of comparison between radical prostatectomy and other definitive options, such as external radiation therapy or brachytherapy. Although a prospective randomized trial comparing radical prostatectomy and prostate brachytherapy has been initiated by the American College of Surgeons Oncology Group (the Surgical Prostatectomy Interstitial Radiation Intervention Trial [SPIRIT]), we must continue to evaluate retrospective data available to us now in order to appropriately counsel our patients.

Unfortunately, there is an inconsistency in the data for the high-risk patients. While the text of the article states that the 5-year actuarial PSA failure-free survival for these patients is 28% and 32% for the two race groups analyzed, the Kaplan-Meier curve in Fig 2 reflects a 10% to 15% higher survival. This is an important outcome to accurately quantify and compare with other available treatments, and it should be clarified.

Additionally, it might be interesting to compare different risk group definitions. Notwithstanding the validation of this particular low-/intermediate-/high-risk group definition introduced by D’Amico et al,² a more widely accepted and simpler definition was first suggested by Zelefsky et al.³ Their definition uses single break points for Gleason score ( 6 or > 6), PSA ( 10 or > 10), and clinical stage ( T2a, > T2a) and defines low, intermediate, and high risk as none, one, or two or more higher-risk features, respectively. This grouping has been more widely accepted in the reporting of external radiation therapy and brachytherapy results. I do not discount the additive value of volume of disease at biopsy as used by Cross et al¹; rather, I simply admire the simplicity and applicability of the Zelefsky definition, even with its flaws (a very heterogeneous intermediate-risk group, for one). It would be a simple matter to report these data using these criteria as well.

I applaud the authors’ admission of immature follow-up at 5 years. The high-risk group biochemical no evidence of disease survival curve does not even suggest a significant plateau in its shape, suggesting that longer follow-up will reveal even poorer disease control than reported.

As we continue with our apples and oranges comparisons that plague the usefulness of comparing different treatments in prostate cancer, it behooves us to recognize widely accepted prognostic groupings and to have mature data series to use for the inevitable head-to-head comparisons of available treatments. Perhaps we can then serve our patients better with more specific suggestions for the optimal therapy in each individual’s case.

REFERENCES

1. Cross CK, Shultz D, Malkowicz SB, et al: Impact of race on prostate-specific antigen outcome after radical prostatectomy for clinically localized adenocarcinoma of the prostate. J Clin Oncol 20: 2863-2868, 2002[Abstract/Free Full Text]

2. D’Amico AV, Whittington R, Malcowicz SB, et al: Biochemical outcome after radical prostatectomy, external beam radiation therapy, or interstitial radiation therapy for clinically localized prostate cancer. JAMA 280: 969-974, 1998[Abstract/Free Full Text]

3. Zelefsky MJ, Leibel SA, Gaudin PB, et al: Dose escalation with three-dimensional conformal radiation therapy affects the outcome in prostate cancer. Int J Radiat Oncol Biol Phys 41: 491-500, 1998[CrossRef][Medline]

Response

Brigham and Women’s Hospital, Boston, MA

In Reply:We are thankful for the interest and comments on our study of race and prostate-specific antigen (PSA) outcome after radical prostatectomy for patients with clinically localized prostate cancer.¹ We agree that beyond low risk, all risk categorizations may contain a heterogeneous patient population with regard to extent and biologic aggressiveness of the disease. However, we did apply a ² metric to test for differences in the proportion of African-American versus white men having a specific pretreatment PSA level, biopsy Gleason score, or clinical T category at diagnosis and did not find any statistically significant differences in the high- or low-risk groups, as shown in Table 2. With that said, there was a numerical but nonstatistically significant difference in PSA outcome among the two races in the high-risk group. This raises the question of whether a true difference in biology existed among the races or whether an imbalance in yet-to-be-defined predictive factors was present. Given the recent reports by Bianco et al² and D’Amico et al³ in 2002 regarding stage migration due to the increased use of PSA-based screening, PSA outcome continues to improve across all races. Therefore, perhaps the numerical differences in PSA outcome across race as noted in the high-risk patients in this study will eventually disappear. Time will tell.

REFERENCES

1. Cross CK, Shultz D, Malkowicz SB, et al: Impact of race on prostate-specific antigen outcome after radical prostatectomy for clinically localized adenocarcinoma of the prostate. J Clin Oncol 20: 2863-2868, 2002[Abstract/Free Full Text]

2. Bianco FJ, Wood DP, Powell IJ, et al: Prostate cancer stage shift has eliminated the gap in disease-free survival in black and white American men after radical prostatectomy. J Urol 168: 479-482, 2002[CrossRef][Medline]

3. D’Amico AV, Chen M-H, Richie JP, et al: Changing natural history following surgery or radiation therapy for localized prostate cancer during the prostate-specific antigen era. Proc Am Soc Clin Oncol 21: 176a, 2002 (abstr 702)

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This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Save to my personal folders Download to citation manager Rights & Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Gray, J. R. Articles by D’Amico, A. Search for Related Content PubMed PubMed Citation Articles by Gray, J. R. Articles by D’Amico, A. Social Bookmarking                            What's this?