About

Gary Freedman, M.D., is a Professor of Radiation Oncology at the Hospital of the University of Pennsylvania within the Perelman School of Medicine. His clinical expertise is focused exclusively on breast cancer, and he has been recognized for clinical excellence by Penn Medicine through induction into the Academy of Master Clinicians in 2013. His academic and research interests are centered on breast cancer treatment, with particular emphasis on shortening radiation courses through hypofractionation, utilizing intensity modulated radiation therapy (IMRT) with concurrent boost, proton beam radiation, and exploring cardiac effects of radiation therapy as well as techniques to reduce cardiac dose in breast cancer patients. Dr. Freedman has contributed extensively to the field, publishing over 100 peer-reviewed manuscripts, review articles, and book chapters related to breast cancer and radiation therapy techniques, indications, and side effects.

Research topics

• Medicine
• Internal medicine
• Oncology
• Surgery
• Nuclear medicine

Selected publications

• Experimental validation and calibration of Cherenkov imaging for real-time surface dosimetry in photon breast therapy

  2026-03-05

  article

  Cherenkov imaging holds promise as a non-invasive, real-time method for surface dosimetry during photon-based external beam radiation therapy (EBRT). In this study, we evaluated the feasibility of using Cherenkov emission as a quantitative surrogate for surface dose in breast cancer treatment through Monte Carlo simulation and experimental validation. A Monte Carlo model was developed to simulate both dose deposition and corresponding Cherenkov photon emission for breast patients undergoing photon EBRT. Validation was performed using phantoms with homogeneous optical properties and varying geometries, enabling direct comparison between simulated and measured Cherenkov emission. Additionally, the simulated surface dose was validated against in-vivo measurements acquired using in-vivo dosimeters. Results show strong correlation between simulated and measured Cherenkov emission and surface dose, except at the field edges, where additional optical and geometric considerations are required. Based on these comparisons, a correction factor was derived to calibrate Cherenkov intensity to absolute surface dose. Finally, Cherenkov images acquired from breast cancer patients were compared with simulation results to assess the clinical utility of this approach. These findings support the use of Cherenkov imaging, when properly corrected, as a viable tool for real-time, patient-specific surface dosimetry in photon EBRT.

  PublisherDOI

• Boost Approaches in Patients Undergoing Postoperative Radiotherapy

  Journal of Surgical Oncology · 2026-03-08

  articleOpen accessSenior authorCorresponding

  The use of breast conservation surgery for early-stage breast cancer is common, and adjuvant radiotherapy is often recommended to reduce the risk of ipsilateral breast tumor recurrence. Historical trials have used sequential boost techniques with favorable outcomes with reduction in local recurrence and acceptable cosmetic outcomes. In recent years, there has been renewed interest in incorporating a concurrent tumor bed boost to reduce the number of radiation treatments delivered. This focused review summarizes the literature surrounding the indications, outcomes, and treatment planning considerations for radiation tumor bed boost for early-stage breast cancer patients.

  PublisherDOI

• The Relationship of Radiation Therapy Parameters and Perioperative Morbidity and Toxicities on Breast Reconstruction Outcomes

  Annals of Plastic Surgery · 2026-02-02

  article

  BACKGROUND: Postmastectomy radiation therapy (PMRT) is a key component of breast cancer care, reducing locoregional recurrence in appropriately selected patients. Concurrently, use of mastectomy with implant-based breast reconstruction has expanded, heightening attention to how patient, surgical, and radiation factors interact. There is a knowledge gap in how reconstructive strategies and PMRT parameters jointly influence complications, toxicities, and treatment timing across the expander-implant continuum. OBJECTIVE: The aim of this study was to determine how reconstructive and radiation therapy (RT) parameters relate to surgical-site complications, delays in PMRT initiation, acute radiation toxicities, delays in expander-to-implant exchange, and capsular contracture. METHODS: This study examined a single-center retrospective cohort of women undergoing mastectomy with immediate tissue expander or direct-to-implant reconstruction and PMRT (2017-2022). Complications classified as postmastectomy pre-RT, intra-RT, and post-RT. Associations between clinical and radiation factors and complications, toxicities, and delays were estimated using generalized estimating equation logistic models. RESULTS: One hundred forty-six patients underwent 260 mastectomies, and 152 reconstructions received PMRT. The majority underwent dual-stage reconstruction (87.5%). Adverse surgical site outcomes occurred in approximately one-quarter of breasts before PMRT and in a similar proportion after PMRT. Neither pre-RT surgical site outcomes delayed PMRT ( P = 0.61) nor did severe dermatitis delay expander-to-implant exchange ( P = 0.63). Severe dermatitis was less frequent with intensity-modulated RT ( P < 0.01) and proton therapy ( P < 0.02) than with three-dimensional conformal RT, whereas bolus use increased the risk of dermatitis ( P < 0.01). Severe capsular contracture occurred less frequently after prepectoral versus submuscular reconstruction, but the difference did not reach statistical significance ( P = 0.30). CONCLUSIONS: In an integrated care setting where PMRT and reconstruction are performed in the same institution, pre-RT complications do not correlate with delaying PMRT, nor do post-RT complications or acute toxicities alter the implant exchange course. Complications were substantial during the pre-RT period, suggesting further opportunities for improvement. These findings emphasize the importance of multidisciplinary planning/communication to optimize patient treatment and outcomes.

  PublisherDOI

• Phase III Randomized Trial of Proton vs. Photon Therapy for Patients with Non-metastatic Breast Cancer Receiving Comprehensive Nodal Radiation: A Radiotherapy Comparative Effectiveness (Radcomp) Consortium Trial: Health-Related Quality of Life Outcomes

  International Journal of Radiation Oncology*Biology*Physics · 2025-10-14 · 3 citations

  article
  PublisherDOI

• Cardiac Effects of Modern Breast Radiation Therapy in Patients Receiving Systemic Cancer Therapy

  JACC CardioOncology · 2025-03-04 · 9 citations

  articleOpen access

  BACKGROUND: Radiation therapy (RT) improves breast cancer outcomes, but cardiac morbidity remains a concern. OBJECTIVES: This study sought to evaluate changes in cardiac function after RT and the relationship between cardiac dose metrics and echocardiography-derived measures of function. METHODS: In a longitudinal cohort study of women with breast cancer, radiation cardiac dose metrics and core lab quantitated echocardiographic measures of cardiac function were evaluated. Dose metrics included the whole heart, left ventricle, right ventricle, and left anterior descending artery (LAD). Echocardiographic measures included left ventricular ejection fraction (LVEF), longitudinal strain, circumferential strain, E/e' (ratio of early diastolic mitral inflow velocity to early diastolic mitral annular tissue velocity), Ea/Es (ventricular arterial coupling; ratio of effective arterial elastance to end systolic elastance), and right ventricular fractional area change. The mean change in echocardiographic measures over time and the association between cardiac dose metrics and echocardiographic measures were estimated by repeated-measures multivariable linear regression via generalized estimating equations. RESULTS: The cohort included 303 participants (median age 52 years, 33.3% African American) who received adjuvant RT (2010-2019) with a median mean heart dose of 1.19 Gy (Q1-Q3: 0.75-2.61 Gy), were followed over a median of 5.1 years (Q1-Q3: 3.2-7.1 years). Across all participants, there was a modest increase in LVEF (52.1% pre-RT to 54.3% at 5 years; P < 0.001) but a worsening in sensitive measures of function, such as circumferential strain (-23.7% pre-RT to -21.0% at 5 years; P = 0.003). Among left-sided/bilateral breast cancer participants, changes in cardiac function were observed across all parameters (P < 0.05). The maximum LAD dose was associated with a modest worsening in LVEF, longitudinal strain, circumferential strain, and E/e'. CONCLUSIONS: Over a median of 5.1 years, modest changes in cardiac function were observed with RT. Maximum LAD dose was associated with a worsening in systolic and diastolic function parameters.

  PublisherDOI

• 3D Echocardiographic Phenotyping of Left Ventricular Mechanics and Function With Contemporary Radiation Therapy

  Advances in Radiation Oncology · 2025-04-16

  articleOpen access

  Purpose: Our objective was to characterize the early changes in cardiac function after thoracic radiation therapy (RT) using 3D echocardiography. Methods and Materials: In a prospective longitudinal cohort study of 69 patients with breast cancer, lung cancer, or mediastinal lymphoma treated with chemotherapy and RT, clinical and 3D echocardiographic data were assessed before, immediately after, and 5 to 9 months after RT completion. 3D left ventricular ejection fraction, global circumferential strain, global longitudinal strain (GLS), average 3D strain, twist, and torsion were quantified. Associations among mean heart dose (MHD), V5, and V30 and early changes in echocardiography-derived measures of cardiac function were assessed with generalized estimating equations. Results: > .05). Conclusions: Early abnormalities in cardiac function as measured by 3D echocardiography can be detected following RT. Additional work is needed to define the determinants of changes in cardiac function with RT and long-term impact of early changes on clinical outcomes.

  PublisherDOI

• 1167 Trajectories of Change in Cancer-related Fatigue and Insomnia over 12 Weeks of Radiation Therapy

  SLEEP · 2025-05-01

  articleOpen access

  Abstract Introduction The impact of radiation therapy (RT) on insomnia and cancer-related fatigue (CRF) among individuals with cancer is not well understood. Our study aimed to 1) examine trajectories of insomnia and CRF across RT and 2) understand whether these trajectories depend on age or sex. Methods Patients with cancer (all types) undergoing RT were recruited immediately prior to starting treatment (N=128; Mage=58.6±12.4y, 38% female, 80% White, 2% Hispanic or Latino). Subjects were asked to report on insomnia and CRF symptoms at baseline and then every 2 weeks for 3 months. Mixed effects models accounting for linear and quadratic effects of time were used to examine change in CRF and insomnia over 12-weeks. Additional models evaluated baseline age and sex as moderators of these relationships. All models were adjusted for the presence of other interventions (e.g., surgery, medications). Results There was no significant linear (p=0.11) or quadratic (p=0.29) effect of time on fatigue, and sex did not moderate this effect. However, age moderated this effect (est=0.003, S.E.=0.001, p=0.03) such that those &amp;lt; 47y reported decreased CRF while those &amp;gt;72y reported increased CRF. There was also no significant linear (p=0.09) or quadratic (p=0.16) effect of time on insomnia, and sex did not moderate this effect. Again, age moderated the effect of time on insomnia (est=0.007, S.E.=0.003, p=0.03) such that those either &amp;lt; 47y or &amp;gt;72y reported reductions in insomnia symptoms with those &amp;lt; 47y reported greater reductions in insomnia symptoms compared to those &amp;gt;72y, while those between 47-72y reported slight increases in insomnia symptoms. Conclusion Findings indicate that those who are older (&amp;gt;72y) report increased CRF during and after RT compared to those who are younger (&amp;lt; 47y), where fatigue decreased more in this age cohort. Changes in both groups were modest. Results suggest that insomnia and CRF function independently in this population, as CRF increased while insomnia decreased within the full sample. Future research should explore additional risk- and maintenance-factors for insomnia and CRF during and after RT. Support (if any) This work was partially supported via a trainee grant provided by Penn’s Department of Radiation Oncology.

  PublisherOA PDFDOI

• Improving Cherenkov-to-dose linearity in tissue for quantitative surface dosimetry during whole breast radiation therapy

  2024-03-13 · 1 citations

  article

  Imaging Cherenkov photons emitted during radiation therapy can provide real-time information of the external beam field. It is well established that Cherenkov emission is correlative to dose deposited; however, differential photon energies and tissue attenuation properties, along with complicated camera geometries, entangle this relationship and introduce variability in the Cherenkov emission-to-dose ratio from patient-to-patient. This study aims to better understand the effects of optical properties, skin color, and patient-specific geometries (i.e. angle of camera incidence and curvature) on the Cherenkov emission-to-dose relationship. To do so, a series of phantom experiments were conducted with tissuesimulating optical phantoms and an andromorphic breast phantom in which optical properties, curvature, and camera angle of incidence were all examined as a function of normalized Cherenkov emission-to-dose. To acquire clinical Cherenkov data along with patient skin color, Cherenkov images and OSLD measurements for the ground-truth surface dose were collected weekly on 13 whole-breast radiotherapy patients, alongside high-resolution 3D color and texture scans. Phantom results suggest there to be a moderately strong correlation between dose percent error and patient curvature (R² = 0.57), as well as angle of camera incidence (R² = 0.56). Initial patient results suggest there to be a correlation between the redness of a patient’s skin, and the Cherenkov emission-to-dose ratio, with higher amounts of redness correlating to lower Cherenkov signal. By better characterizing these trends, we are potentially able to find generalizable optics-based corrections that improve the accuracy in mapping Cherenkov emission to real-time skin dose.

  PublisherDOI

• ASO Visual Abstract: Guideline-Concordant Surgical Care for Lobular Versus Ductal Inflammatory Breast Cancer

  Annals of Surgical Oncology · 2024-07-15

  article
  PublisherDOI

• Radiation-Associated Secondary Cancer in Patients With Breast Cancer Harboring <i>TP53</i> Germline Variants

  JAMA Oncology · 2024-09-12 · 2 citations

  articleOpen access

  This cohort study examines the risk of radiation-associated sarcoma in patients with breast cancer harboring germline TP53 variants.

  PublisherOA PDFDOI

Frequent coauthors

• André Konski

  University of Pennsylvania

  72 shared

• Penny R. Anderson

  67 shared

• John P. Hoffman

  57 shared

• Lawrence B. Marks

  UNC Lineberger Comprehensive Cancer Center

  47 shared

• Neil K. Taunk

  42 shared

• Joachim Yahalom

  Memorial Sloan Kettering Cancer Center

  41 shared

• William Small

  Loyola University Medical Center

  41 shared

• Michelle L. Klem

  Princess Margaret Cancer Centre

  41 shared

Education

• MD, School of Medicine

  Temple University

  1993

Awards & honors

• Induction into the Academy of Master Clinicians (2013)
• Castle Connolly / Philadelphia Top Doctors (2009 - 2025)