Biologically Effective Dose (BED) Correlation With Biochemical Control After Low-Dose Rate Prostate Brachytherapy for Clinically Low-Risk Prostate Cancer

Journal Article · Sat May 01 04:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.04.052· OSTI ID:21372252

Nelson, John W; Alkaissi, Ali K; Das, Shiva; Clough, Robert W ^[1]; Broadwater, Gloria ^[2]; Anscher, Mitchell S; Chino, Junzo P; Oleson, James R ^[1]

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1. Department of Radiation Oncology, Duke University Medical Center, Durham, NC (United States)
2. Cancer Center Biostatistics, Duke University Medical Center, Durham, NC (United States)

Purpose: To assess the correlation of postimplant dosimetric quantifiers with biochemical control of prostate cancer after low-dose rate brachytherapy. Methods and Materials: The biologically effective dose (BED), dose in Gray (Gy) to 90% of prostate (D{sub 90}), and percent volume of the prostate receiving 100% of the prescription dose (V{sub 100}) were calculated from the postimplant dose-volume histogram for 140 patients undergoing low-dose rate prostate brachytherapy from 1997 to 2003 at Durham Regional Hospital and the Durham VA Medical Center (Durham, NC). Results: The median follow-up was 50 months. There was a 7% biochemical failure rate (10 of 140), and 91% of patients (127 of 140) were alive at last clinical follow-up. The median BED was 148 Gy (range, 46-218 Gy). The median D{sub 90} was 139 Gy (range, 45-203 Gy). The median V{sub 100} was 85% (range, 44-100%). The overall 5-year biochemical relapse-free survival (bRFS) rate was 90.1%. On univariate Cox proportional hazards modeling, no pretreatment characteristic (Gleason score sum, age, baseline prostate-specific antigen, or clinical stage) was predictive of bRFS. The BED, D{sub 90}, and V{sub 100} were all highly correlated (Pearson coefficients >92%), and all were strongly correlated with bRFS. Using the Youden method, we identified the following cut points for predicting freedom from biochemical failure: D{sub 90} >= 110 Gy, V{sub 100} >= 74%, and BED >= 115 Gy. None of the covariates significantly predicted overall survival. Conclusions: We observed significant correlation between BED, D{sub 90}, and V{sub 100} with bRFS. The BED is at least as predictive of bRFS as D{sub 90} or V{sub 100}. Dosimetric quantifiers that account for heterogeneity in tumor location and dose distribution, tumor repopulation, and survival probability of tumor clonogens should be investigated.

• OSTI ID: 21372252
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 1 Vol. 77; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BODY
BRACHYTHERAPY
CONTROL
CORRELATIONS
DISEASES
DOSE RATES
DOSES
DOSIMETRY
GLANDS
MALE GENITALS
MEDICINE
NEOPLASMS
NUCLEAR MEDICINE
ORGANS
PROSTATE
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
THERAPY