Bridget Koontz

Overview:

Clinical: Board-certified in radiation treatment for all cancer locations/types.
Research: The long-term goal of Dr. Koontz’s research is to minimize treatment-related side effects of radiotherapy.  To that end she has a laboratory studying the mechanisms of radiation induced erectile dysfunction and testing interventions to treat and prevent this devastating side effect of radiotherapy.  Her clinical research investigates optimizing prostate cancer treatment and utilizes collaborations with colleagues in surgery and psychiatry to pursue further understanding of how sexual dysfunction develops after radiotherapy and how to improve patient-provider interactions regarding the sexuality and intimacy consequences of cancer therapy.

Positions:

Associate Professor of Radiation Oncology

Radiation Oncology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

B.S. 1998

Allegheny College

M.D. 2002

Harvard University

Internship

University of North Carolina at Chapel Hill School of Medicine

Residency Training, Radiation Oncology

Duke University School of Medicine

Grants:

Publications:

Tolerance doses for late adverse events after hypofractionated radiotherapy for prostate cancer on trial NRG Oncology/RTOG 0415.

PURPOSE/OBJECTIVE: Hypofractionated radiotherapy (HRT) regimens for prostate cancer are emerging, but tolerance doses for late adverse events are scarce. The purpose of this study is to define dose-volume predictors for late gastrointestinal and genitourinary (GI and GU) toxicities after HRT in the multi-center NRG Oncology/RTOG 0415 low-risk prostate cancer trial (N = 521). MATERIAL/METHODS: Treatment in the studied HRT arm was delivered as 70 Gy at 2.5 Gy/fraction with 3D-CRT/IMRT (N = 108/413). At a median follow-up of 5.9 years, the crude late ≥Grade 2 GI and GU toxicities were 19% and 29%, respectively. For modeling, the complete HRT cohort was randomly split into training and validation (70% and 30%; preserved toxicity rates). Within training, dose-response modeling was based on dose-volume cut-points (EQD2Gy; bladder/rectum: α/β = 6 Gy/3Gy), age, acute ≥Grade 2 toxicity, and treatment technique using univariate and multivariate logistic regression on bootstrapping (UVA and MVA). Candidate predictors were determined at p ≤ 0.05, and the selected MVA models were explored on validation where model generalizability was judged if the area under the receiver-operating curve in validation (AUCvalidation) was within AUCtraining ± SD with p ≤ 0.05, and with an Hosmer-Lemeshow p-value (pHL) > 0.05. RESULTS: Three candidate predictors were suggested for late GI toxicity: the minimum dose to the hottest 5% rectal volume (D5%[Gy]), the absolute rectal volume <35 Gy, and acute GI toxicity (AUC = 0.59-0.63; p = 0.02-0.04). The two generalizable MVA models, i.e., D5%[Gy] with or without acute GI toxicity (AUCvalidation = 0.64, 0.65; p = 0.01, 0.03; pHL = 0.45-0.56), suggest that reducing late GI toxicity from 20% to 10% would require reducing D5%[Gy] from ≤65 Gy to ≤62 Gy (logistic function argument: 17+(0.24D5%[Gy])). Acute GU toxicity showed only a trend to predict late GU toxicity (AUCtraining = 0.57; p = 0.07). CONCLUSION: Late GI toxicity, following moderate HRT for low-risk prostate cancer, increases with higher doses to small rectal volumes. This work provides quantitative evidence that limiting small rectal dose 'hotspots' in clinical practice of such HRT regimens is likely to further reduce the associated rates of GI toxicity.
Authors
Thor, M; Deasy, JO; Paulus, R; Robert Lee, W; Amin, MB; Bruner, DW; Low, DA; Shah, AB; Malone, SC; Michalski, JM; Dayes, IS; Seaward, SA; Gore, EM; Albert, M; Pisansky, TM; Faria, SL; Chen, Y; Koontz, BF; Swanson, GP; Pugh, SL; Sandler, HM
MLA Citation
Thor, Maria, et al. “Tolerance doses for late adverse events after hypofractionated radiotherapy for prostate cancer on trial NRG Oncology/RTOG 0415..” Radiother Oncol, vol. 135, June 2019, pp. 19–24. Pubmed, doi:10.1016/j.radonc.2019.02.014.
URI
https://scholars.duke.edu/individual/pub1373470
PMID
31015166
Source
pubmed
Published In
Radiother Oncol
Volume
135
Published Date
Start Page
19
End Page
24
DOI
10.1016/j.radonc.2019.02.014

Development and Preliminary Evaluation of a Murine Model of Chronic Radiation-Induced Proctitis.

PURPOSE: Radiotherapy (RT) is commonly used to treat most pelvic malignancies. While treatment is often effective, curative radiation doses to the rectum can result in chronic radiation-induced proctitis, which is characterized by diarrhea, tenesmus, and/or rectal bleeding, recently termed pelvic radiation disease. An animal model of chronic radiation-induced proctitis would be useful to test both preventative and therapeutic strategies to limit this morbidity but has been elusive because of the high rodent mortality associated with acute bowel RT injury. The objective of this research was to develop a novel mouse model of chronic radiation-induced proctitis using advanced technology. METHODS AND MATERIALS: Using an X-RAD 225-Cx (Precision X-Ray) small animal irradiator, multiple plan configurations were evaluated for planning treatment volume and organ-at-risk avoidance to deliver a 15 Gy 3D conformal treatment plan. The final plan was verified by high resolution 3D dosimetry (PRESAGE/optical-CT), and delivered using a single arc. Mice were monitored for mortality for 250 days, followed by histopathological correlates including mucicarmine, Masson's trichrome, and fecal pellet length. RESULTS: Six beam arrangements were considered: single and parallel-opposed fields with whole-pelvis coverage, and collimated fields in parallel-opposed, 3-field, 4-field, and arc geometries. A collimated arc plan offered superior planning treatment volume coverage and organ-at-risk avoidance compared to whole-pelvis irradiation. Treatment verification with PRESAGE 3D dosimetry (Heuris Inc) showed >99% of voxels passing gamma analysis with 2%/2 mm criteria. Our treatment resulted in no acute mortality and 40% mortality at 250 days. Histopathological analysis showed increased mucous production and fibrosis of the irradiated colon, but no change in fecal pellet length. CONCLUSIONS: Our model was able to target successfully lower colon and rectum with lower mortality than other published models. This permitted measurement of late effects that recapitulate some features of rectal damage in humans.
Authors
Ashcraft, KA; Miles, D; Sunday, ME; Choudhury, KR; Young, KH; Palmer, GM; Patel, P; Woska, EC; Zhang, R; Oldham, M; Dewhirst, MW; Koontz, BF
MLA Citation
Ashcraft, Kathleen A., et al. “Development and Preliminary Evaluation of a Murine Model of Chronic Radiation-Induced Proctitis..” Int J Radiat Oncol Biol Phys, vol. 101, no. 5, Aug. 2018, pp. 1194–201. Pubmed, doi:10.1016/j.ijrobp.2018.04.061.
URI
https://scholars.duke.edu/individual/pub1331278
PMID
30012529
Source
pubmed
Published In
Int J Radiat Oncol Biol Phys
Volume
101
Published Date
Start Page
1194
End Page
1201
DOI
10.1016/j.ijrobp.2018.04.061

Stereotactic Body Radiation Therapy for Oligometastatic Prostate Cancer: The Hunt for the Silver Bullet.

Authors
MLA Citation
Koontz, Bridget F. “Stereotactic Body Radiation Therapy for Oligometastatic Prostate Cancer: The Hunt for the Silver Bullet..” Int J Radiat Oncol Biol Phys, vol. 99, no. 4, Nov. 2017, pp. 761–63. Pubmed, doi:10.1016/j.ijrobp.2017.05.020.
URI
https://scholars.duke.edu/individual/pub1314236
PMID
29063841
Source
pubmed
Published In
Int J Radiat Oncol Biol Phys
Volume
99
Published Date
Start Page
761
End Page
763
DOI
10.1016/j.ijrobp.2017.05.020

Etiology of Radiation-Induced Erectile Dysfunction: Vessel or Nerve?

Authors
Koontz, BF; Ashcraft, K; Faught, A; Patel, P; Woska, E; Mao, L; Dewhirst, MW
MLA Citation
Koontz, B. F., et al. “Etiology of Radiation-Induced Erectile Dysfunction: Vessel or Nerve?.” Int J Radiat Oncol Biol Phys, vol. 96, no. 2S, Oct. 2016, pp. E590–91. Pubmed, doi:10.1016/j.ijrobp.2016.06.2107.
URI
https://scholars.duke.edu/individual/pub1146598
PMID
27675100
Source
pubmed
Published In
Int J Radiat Oncol Biol Phys
Volume
96
Published Date
Start Page
E590
End Page
E591
DOI
10.1016/j.ijrobp.2016.06.2107

External beam radiation therapy for clinically localized prostate cancer

© Springer-Verlag London 2015. All rights reserved. Radiation therapy is used in approximately one-third of patients newly diagnosed with prostate cancer. External beam radiotherapy alone to doses of 75.6 Gy or higher is appropriate for patients with low risk disease (T1, GS<7, PSA≤10 ng/ml). For intermediate or high risk disease, numerous randomized trials indicate that outcomes are improved by addition of androgen deprivation. In the postoperative setting, Level I evidence supports the use of adjuvant radiotherapy for certain pathologic feature’s (pathologic T3 or positive surgical margins) but debate continues whether early salvage radiotherapy (post-operative PSA <0.5 ng/ml) will be just as effective. Radiation technology continues to improve, with both intensity-modulated and image-guided radiotherapy commonly available. These techniques allow significant reduction in dose to normal tissues, lowering the risk of radiation toxicities. Additionally, this technology has allowed for hypofractionation (fewer, larger treatment fractions) which significantly shorten treatment courses.
Authors
MLA Citation
Koontz, B. F., and W. R. Lee. “External beam radiation therapy for clinically localized prostate cancer.” Urological Oncology, 2015, pp. 731–42. Scopus, doi:10.1007/978-0-85729-482-1_42.
URI
https://scholars.duke.edu/individual/pub1108471
Source
scopus
Published Date
Start Page
731
End Page
742
DOI
10.1007/978-0-85729-482-1_42

Research Areas:

Adult
Aged
Androgen Antagonists
Animals
Antibodies, Monoclonal
Biological Markers
Bone Neoplasms
Brachytherapy
Breast Neoplasms
Chemotherapy, Adjuvant
Clinical Trials as Topic
Combined Modality Therapy
Disease Models, Animal
Disease-Free Survival
Dose-Response Relationship, Radiation
Epidemiologic Methods
Erectile Dysfunction
Follow-Up Studies
Head and Neck Neoplasms
Health Facilities
Heart Diseases
Hospitals
Humans
Indicators and Reagents
Indium Radioisotopes
Inflammation
Lymph Nodes
Lymphatic Irradiation
Male
Mammary Glands, Human
Matched-Pair Analysis
Middle Aged
Models, Molecular
Morbidity
NADPH Oxidase
NADPH Oxidases
Neoadjuvant Therapy
Neoplasm Grading
Neoplasm Invasiveness
Neoplasm Recurrence, Local
Neoplasm Staging
Neoplasms, Hormone-Dependent
Neoplasms, Radiation-Induced
North Carolina
Organ Specificity
Oxidative Stress
Palliative Care
Patient Care Team
Patient Selection
Pelvis
Penile Erection
Penile Prosthesis
Penis
Preoperative Care
Prostate
Prostate-Specific Antigen
Prostatectomy
Prostatic Neoplasms
Radiation Dosage
Radiation Injuries
Radiation Injuries, Experimental
Radiosurgery
Radiotherapy
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Adjuvant
Radiotherapy, Conformal
Radiotherapy, High-Energy
Rats
Rats, Sprague-Dawley
Retrospective Studies
Risk Assessment
Risk Factors
Salvage Therapy
Soft Tissue Neoplasms
Survival Rate
Tomography, X-Ray Computed
Treatment Outcome
Tumor Markers, Biological
Urinary Bladder