Radiation dose and late failures in prostate cancer

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• 作者：Peter B. Morgan ; Alex ; ra L. Hanlon ; Eric M. Horwitz ; Mark K. Buyyounouski ; Robert G. Uzzo ; Alan Pollack
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：2007
• 期刊代码：136_03603016
• 类别：med
• 出版时间：15 March 2007
• 卷：67
• 期：4
• 页码：1074-1081
• 文件大小：369 K

摘要

Purpose: To quantify the impact of radiation dose escalation on the timing of biochemical failure (BF) and distant metastasis (DM) for prostate cancer treated with radiotherapy (RT) alone.

Methods: The data from 667 men with clinically localized intermediate- and high-risk prostate cancer treated with three-dimensional conformal RT alone were retrospectively analyzed. The interval hazard rates of DM and BF, using the American Society for Therapeutic Radiology and Oncology (ASTRO) and Phoenix (nadir + 2) definitions, were determined. The median follow-up was 77 months.

Results: Multivariate analysis showed that increasing radiation dose was independently associated with decreased ASTRO BF (p < 0.0001), nadir + 2 BF (p = 0.001), and DM (p = 0.006). The preponderance (85%) of ASTRO BF occurred at ≤4 years after RT, and nadir + 2 BF was more evenly spread throughout Years 1–10, with 55%of BF in ≤4 years. Radiation dose escalation caused a shift in the BF from earlier to later years. The interval hazard function for DM appeared to be biphasic (early and late peaks) overall and for the <74-Gy group. In patients receiving ≥74 Gy, a reduction occurred in the risk of DM in the early and late waves, although the late wave appeared reduced to a greater degree.

Conclusion: The ASTRO definition of BF systematically underestimated late BF because of backdating. Radiation dose escalation diminished and delayed BF; the delay suggested that local persistence may still be present in some patients. For DM, a greater radiation dose reduced the early and late waves, suggesting that persistence of local disease contributed to both.