TY - JOUR
T1 - Radiation dose and late failures in prostate cancer
AU - Morgan, Peter B.
AU - Hanlon, Alexandra L.
AU - Horwitz, Eric M.
AU - Buyyounouski, Mark K.
AU - Uzzo, Robert G.
AU - Pollack, Alan
PY - 2007/3/15
Y1 - 2007/3/15
N2 - 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.
AB - 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.
KW - Biochemical failure
KW - Distant metastasis
KW - Hazard function
KW - Prostate cancer
KW - Radiation dose
UR - http://www.scopus.com/inward/record.url?scp=33847332625&partnerID=8YFLogxK
U2 - 10.1016/j.ijrobp.2006.10.023
DO - 10.1016/j.ijrobp.2006.10.023
M3 - Article
SN - 0360-3016
VL - 67
SP - 1074
EP - 1081
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 4
ER -