Radiation dose response in patients with favorable localized prostate cancer (Stage T1-T2, biopsy Gleason ≤ 6, and pretreatment prostate-specific antigen ≤ 10)

Patrick A. Kupelian, Jeffrey C. Buchsbaum, Chandana A. Reddy, Eric A. Klein

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

Purpose: To study the radiation dose response as determined by biochemical relapse-free survival in patients with favorable localized prostate cancers, i.e., Stage T1-T2, biopsy Gleason score (bGS) ≤ 6, and pretreatment prostate-specific antigen (iPSA) ≤ 10 ng/mL. Methods and Materials: A total of 292 patients with favorable localized prostate cancer were treated with radiotherapy alone between 1986 and 1999. The median age was 69 years. Sixteen percent of cases (n = 46) were African-American. The distribution by clinical T stage was as follows: T1/T2A, 243 (83%); and T2B/T2C, 49 (17%). The distribution by iPSA was as follows: ≤ 4 ng/mL, 49 (17%); and > 4 ng/mL, 243 (83%). The mean iPSA level was 6.2 (median, 6.4). The distribution by bGS was as follows: ≤ 5 in 89 cases (30%) and 6 in 203 cases (70%). The median radiation dose was 70.0 Gy (range, 63.0-78.0 Gy). Doses of ≤ 70.0 Gy were delivered in 175 cases, 70.2-72.0 Gy in 24 cases, 74 Gy in 30 cases, and 78 Gy in 63 cases. For patients receiving < 72 Gy, the median dose was 68 Gy, vs. 78 Gy for patients receiving ≥ 72 Gy. A conformal technique was used in 129 (44%) of cases. The median follow-up was 43 months (range, 3-153). Results: For the entire cohort, the projected 5- and 8-year biochemical relapse-free survival (bRFS) rates were both 81%. For patients receiving ≥ 72 Gy, the 5- and 8-year bRFS rates were both 95% vs. only 77% for patients receiving < 72 Gy, p = 0.010. For patients receiving 74 Gy, the 4-year bRFS rate was 94% vs. 96% for patients receiving 78 Gy, p = 0.90. A multivariate analysis for factors affecting bRFS rates using Cox proportional hazards was performed for all cases using the following variables: age (continuous variable), race (black vs. white), iPSA (continuous variable), bGS (≤ 5 vs. 6), Stage (T1-2A vs. T2B-C), radiation dose (continuous variable), and radiation technique (conformal vs. standard). From the multivariate analysis, only iPSA (p = 0.017, χ 2 = 5.7), and radiation dose (p = 0.021, χ 2 = 5.3) were independent predictors of outcome. Age (p = 0.94), race (p = 0.89), stage (p = 0.45), biopsy GS (p = 0.40), and radiation technique (p = 0.45) were not. Conclusion: There is a clear radiation dose response in patients with favorable localized prostate cancers (i.e., Stage T1-T2, biopsy Gleason score ≤ 6, and iPSA ≤ 10 ng/mL). At least 74 Gy should be delivered to the prostate and periprostatic tissues. With our cohort of patients, longer follow-up will be needed to assess the importance of doses exceeding 74 Gy.

Original languageEnglish (US)
Pages (from-to)621-625
Number of pages5
JournalInternational Journal of Radiation Oncology Biology Physics
Volume50
Issue number3
DOIs
StatePublished - Jul 1 2001

Keywords

  • Biochemical relapse-free survival
  • Localized prostate cancer
  • Radiation dose
  • Radiotherapy

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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