High-dose regions versus likelihood of cure after prostate brachytherapy
- Department of Radiation Oncology, Puget Sound Health Care System, Department of Veterans Affairs, Seattle, WA (United States) and Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA (United States) and Group Health Cooperative, Seattle, WA (United States)
- Schiffler Cancer Center, Wheeling, WV (United States)
- Department of Radiation Oncology, Puget Sound Health Care System, Department of Veterans Affairs, Seattle, WA (United States)
- Department of Pathology, University of Washington School of Medicine, Seattle, WA (United States)
Purpose: To analyze the effect of high-dose regions on biochemical cancer control rates after prostate brachytherapy. Methods and Materials: Patients with 1997 American Joint Committee on Cancer clinical Stage T1c-T2a prostate carcinoma (Gleason grade 5-6, prostate-specific antigen level 4-10 ng/mL) were randomized to implantation with {sup 125}I (144 Gy) vs. {sup 103}Pd (125 Gy, National Institute of Standards and Technology 1999). Isotope implantation was performed by standard techniques, using a modified peripheral loading pattern. Of the 313 patients entered in the protocol, 270 were included in this analysis. The {sup 125}I source strength ranged from 0.4 to 0.89 mCi (median, 0.55 mCi), and the {sup 103}Pd source strength ranged from 1.3 to 1.6 mCi (median, 1.5 mCi). CT was performed within 4 h after implantation. The dosimetric parameters analyzed included the percentage of the postimplant prostate volume covered by the 100%, 150%, 200%, and 300% prescription dose (V{sub 100}, V{sub 150}, V{sub 200}, and V{sub 300}, respectively). The median time to the last follow-up for patients without failure was 2.7 years. Freedom from biochemical failure was defined as a serum prostate-specific antigen level of {<=}0.5 ng/mL at last follow-up. Patients were censored at last follow-up if their serum prostate-specific antigen level was still decreasing. Results: The mean V{sub 100}, V{sub 150}, V{sub 200}, and V{sub 300} value was 90% ({+-}8%), 63% ({+-}14), 35% ({+-}13%), and 14% ({+-}7%), respectively. Patients with a V{sub 100} of {>=}90% had a 3-year freedom from biochemical failure rate of 96% vs. 87% for those with a V{sub 100} of <90% (p = 0.0029). Overall, patients with more high-dose regions had a greater chance of biochemical control. However, when only patients with a V{sub 100} of {>=}90% were analyzed, no relationship was found between higher dose regions and the likelihood of cancer control. This lack of effect on biochemical control was apparent for both isotopes. Conclusion: High-dose regions do not appear to affect cancer control rates, as long as >90% of the prostate volume is covered by the prescription dose.
- OSTI ID:
- 20698424
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 62, Issue 1; Other Information: DOI: 10.1016/j.ijrobp.2004.09.021; PII: S0360-3016(04)02581-7; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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