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In Reply

Harvard Radiation Oncology Program, Boston, MA

Anthony V. D'Amico

Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Boston, MA

We are grateful for the thoughtful comments provided by Dr Roach, and would like to address some of the important points that were raised. Though the primary end point of progression-free survival between whole pelvis radiation therapy (WPRT) and prostate-only radiation therapy (PORT) in Radiation Therapy Oncology Group (RTOG) 94-13 was reached in 2003, and was significant (P = .023), the updated results with longer follow-up show that the two curves are no longer different (P = .99).^1,2 If there were a true underlying benefit to prostate cancer–specific end points that was overshadowed by death as a result of other causes, then cumulative incidence estimates of prostate cancer–specific events stratified by WPRT versus PORT might have demonstrated this, but were not provided.

If the four arms are considered separately, which the study was not intended to do, then the relationship between any two arms is described by the pairwise comparisons. As the article points out, because there are six possible comparisons among the four curves, a significance level of P = .05/6 = .008 must be used. Therefore the difference between WPRT plus neoadjuvant hormonal therapy (NHT) versus PORT plus NHT in terms of progression-free survival (P = .066) and the Phoenix definition of biochemical failure (P = .0098) are not statistically significant.¹ In addition, even setting aside the stricter significance level, the WPRT plus NHT arm was indistinguishable from the PORT plus adjuvant hormonal therapy arm in terms of progression-free survival (P = .75) and biochemical recurrence (P value not given, but curves in Fig 5B seem superimposable), so those who favor WPRT plus NHT based on the four-arm comparison might also be compelled to favor PORT plus adjuvant hormonal therapy.

Among randomized trials of RT alone versus RT plus hormones showing a benefit to the addition of hormones, four used WPRT^3-6 and two used PORT,^7,8 but as all six trials used the same radiation field in both arms, no conclusion can be drawn from them about the value of the particular radiation field used. In the two randomized trials that specifically tested the role of WPRT,^1,9 no advantage was demonstrated for WPRT. Given the potential for increased toxicity,¹ based on class I evidence, it is difficult to justify inclusion of pelvic lymph nodes in the treatment volume for the type of men studied in the RTOG 94-13 and Groupe d'Etude des Tumeurs Uro-Génitales trial 01. We look forward to the long-term results of secondary end points of RTOG 94-13 such as cause-specific and overall survival.

AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST

The author(s) indicated no potential conflicts of interest.

REFERENCES

1. Lawton CA, DeSilvio M, Roach M III, et al: An update of the phase III trial comparing whole pelvic to prostate only radiotherapy and neoadjuvant to adjuvant total androgen suppression: Updated analysis of RTOG 94-13, with emphasis on unexpected hormone/radiation interactions. Int J Radiat Oncol Biol Phys 69:646-655, 2007[Medline]

2. Roach M III, DeSilvio M, Lawton C, et al: Phase III trial comparing whole-pelvic versus prostate-only radiotherapy and neoadjuvant versus adjuvant combined androgen suppression: Radiation Therapy Oncology Group 9413. J Clin Oncol 21:1904-1911, 2003[Abstract/Free Full Text]

3. Bolla M, Gonzalez D, Warde P, et al: Improved survival in patients with locally advanced prostate cancer treated with radiotherapy and goserelin. N Engl J Med 337:295-300, 1997[Abstract/Free Full Text]

4. Hanks GE, Pajak TF, Porter A, et al: Phase III trial of long-term adjuvant androgen deprivation after neoadjuvant hormonal cytoreduction and radiotherapy in locally advanced carcinoma of the prostate: The Radiation Therapy Oncology Group Protocol 92-02. J Clin Oncol 21:3972-3978, 2003

5. Pilepich MV, Winter K, John MJ, et al: Phase III radiation therapy oncology group (RTOG) trial 86-10 of androgen deprivation adjuvant to definitive radiotherapy in locally advanced carcinoma of the prostate. Int J Radiat Oncol Biol Phys 50:1243-1252, 2001[CrossRef][Medline]

6. Pilepich MV, Winter K, Lawton CA, et al: Androgen suppression adjuvant to definitive radiotherapy in prostate carcinoma: Long-term results of phase III RTOG 85-31. Int J Radiat Oncol Biol Phys 61:1285-1290, 2005[CrossRef][Medline]

7. D'Amico AV, Chen MH, Renshaw AA, et al: Androgen suppression and radiation vs radiation alone for prostate cancer: A randomized trial. JAMA 299:289-295, 2008[Abstract/Free Full Text]

8. Denham JW, Steigler A, Lamb DS, et al: Short-term androgen deprivation and radiotherapy for locally advanced prostate cancer: Results from the Trans-Tasman Radiation Oncology Group 96.01 randomised controlled trial. Lancet Oncol 6:841-850, 2005[CrossRef][Medline]

9. Pommier P, Chabaud S, Lagrange JL, et al: Is there a role for pelvic irradiation in localized prostate adenocarcinoma? Preliminary results of GETUG-01. J Clin Oncol 25:5366-5373, 2007[Abstract/Free Full Text]

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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 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 Nguyen, P. L. Articles by D'Amico, A. V. Search for Related Content PubMed Articles by Nguyen, P. L. Articles by D'Amico, A. V. Social Bookmarking                            What's this?