Partial breast irradiation with proton therapy
For partial breast irradiation, the conformal dose patterns produced by proton therapy are designed to focus on the lumpectomy site in the breast and to avoid heart and lung tissue.

Radiation oncologists at Penn Medicine are conducting a clinical trial to determine the feasibility and safety of accelerated partial breast irradiation (APBI) using proton radiotherapy (PRT) in women with stage 0, I and II breast cancer who have undergone breast-conserving surgery.

Currently, 3D-conformal external beam radiotherapy (3D-CRT) is the leading method of non-invasive APBI delivery. External beam radiation has the advantage of being flexible for a wide range of eligible patients, and has a higher relative dose to other quadrants of the breast than internal radiation therapy (i.e., interstitial breast brachytherapy).

Interstitial breast brachytherapy offers a highly conformal and localized dose to the tumor bed, but is invasive and more restricted in eligible patients.

As an alternative to these well-established therapies, proton beam radiotherapy (PRT) for APBI offers an opportunity to benefit from the therapy’s unique dosimetric characteristics, providing the convenience and noninvasiveness of 3D-CRT and the superior conformality of brachytherapy. Proton therapy deposits dose at a finite range dependent upon the energy of the beam. Thus, the exit dose seen with protons is dramatically reduced compared to that of photon therapy.

This decrease in dose would be expected to significantly reduce the volume of normal breast tissue receiving the prescription dose and to dramatically reduce exit dose to the underlying heart and/or lung. The comparative brevity of the treatment period offers a further advantage for proton therapy: five to ten days versus six weeks for standard radiotherapy.

A clinical trial is currently enrolling at Penn Medicine to evaluate the safety and feasibility of PRT for APBI in women with early stage breast cancer.

A feasibility and Phase II trial of accelerated partial breast irradiation using proton therapy for women with stage 0, I and II breast cancer

Objectives: The purpose of the APBI Proton Therapy study is to examine the feasibility, side effects and clinical efficacy of proton therapy on only the tumor bed of women being treated for breast cancer after surgical removal of malignancy (as opposed to whole breast treatment).

Methods: Informed consent will be gathered from patients at the Hospital of the University of Pennsylvania. To be eligible, the patient must be female and older than 50 years of age with either invasive ductal, medullary, papillary, colloid (mucinous) or tubular histologies of stage 0, IA-IIA breast cancer; ECOG performance status of 0-2; have margins > 2mm; be lymph node negative or have only microscopic node disease; and have estrogen- or progesterone-positive breast cancer, among other criteria.

A pre-treatment planning CT scan will determine a variety of parameters, including the clinical target volumes, defined as the gross tumor volume with a small additional margin to account for microscopic extension of disease. Organs at risk to be avoided (i.e., lung and heart tissue) will be located on the CT. Dose constraints will be delineated for the skin, ipsilateral and contralateral whole breast reference volumes, thyroid, lung (right/left), heart and spinal cord.

Treatment: A total dose of 38.5 CGE will be prescribed. Two fractions, each of 3.85 CGE, separated by at least 6 hours, will be administered on 5 treatment days (over a period of 5 to 10 days) for a total of 10 fractions. Proton radiation therapy (a 230 MeV proton beam) will be completed within two weeks of treatment initiation in most instances.

Principal Investigator: Gary M. Freedman, MD

Contact: 215.614.0756

For a full description of this trial, see Identifier NCT01839838.

Information about clinical studies in cancer at Penn Medicine can be found here.


Penn Radiation Oncology
Perelman Center for Advanced Medicine
Concourse Level
3400 Civic Center Boulevard
Philadelphia, PA 19104

Abramson Cancer Center
Penn Presbyterian Medical Center
Medical Arts Building, Suite 103A
51 N 39th Street
Philadelphia, PA 19104

Published on: June 1, 2017


APBI Proton Feasibility and Phase II Study: Clinical Identifier NCT01839838.

About Penn Radiation Oncology

Among the largest and most respected programs in the world, Penn Radiation Oncology offers a variety of innovative treatment options to patients with cancer. In addition, as a national leader in basic science, translational research and clinical trials, Penn Radiation Oncology offers patients access to the latest treatment options — including proton therapy — before they are widely available elsewhere.

Penn Faculty Team

Gary M. Freedman, MD

Chief, Women's Health Service, Radiation Oncology

Professor of Radiation Oncology at the Hospital of the University of Pennsylvania

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