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Breast Cancer

Proton Therapy for Breast Cancer

Proton therapy is a non-surgical, non-invasive form of radiation therapy. Proton therapy has unique attributes that reduce radiation exposure to normal, healthy tissue and organs such as the lungs, heart, and important blood vessels. Compared to intensity modulated radiation therapy (IMRT) and 3-D conformal radiotherapy (3-D CRT), the radiation dose to the heart and lungs is significantly reduced when treating breast cancer with proton therapy. In many cases, the impact on the heart from proton therapy can be the same as in women who have never received radiation therapy.

Thompson Proton Center is the ONLY proton therapy center in East Tennessee, allowing you to receive state-of-the-art care close to home.

About Breast Cancer

  • Breast cancer occurs when cells of the breast grow out of control. 
  • 1 in 8 women will develop breast cancer in their lifetime. 
  • Both men and women can develop breast cancer. 
  • When detected and treated early, the survival rate for breast cancer patients is extremely high. 

How Proton Therapy Works

Proton therapy can treat head and neck cancers precisely while lowering the risk for side effects during and after treatment. 

Proton therapy uses charged particles (protons) rather than x-rays to destroy cancer cells. Protons can be focused directly on the tumor and stop at that target in the body. With extreme accuracy, proton therapy results in excellent rates of cancer control with a lower risk for side effects than other forms of radiation therapy. 

The controlled delivery and dosage of proton energy allows direct, customized targeting of the tumor, for the maximum prescribed dosage of radiation. These characteristics of proton therapy can benefit the patient:

  • Improved quality of life, during and after treatment, from greater precision in treating the tumor.
  • Lower risk of side effects and impact to bodily functions, as unnecessary radiation to nearby healthy tissue and vital organs is prevented.
  • Cancer in critical areas or close to organs and structures that could be damaged by radiation can be safely targeted and treated.
  • Patients with cancer recurrence, who have previously been treated with radiation can often safely and effectively be retreated with proton therapy to achieve local control. 

The physical properties of protons, described by the Bragg-Peak (Figure 1), and the increased conformality of pencil beam scanning to conform to the exact shape of the cancer, make it possible to spare healthy surrounding organs from exposure to unnecessary radiation. 

Proton therapy is able to deliver a more targeted dose of energy to the tumor site compared to traditional radiation therapy.
As shown here in the Bragg-Peak, proton therapy is able to deliver a more targeted dose of energy to the tumor site compared to traditional radiation therapy.
Proton therapy reduces radiation exposure to healthy tissue and vital organs in breast cancer patients, compared to traditional radiation.
Radiation Exposure in Proton Therapy vs. Traditional Radiation for Breast Cancer Patients

Clinical Benefits of Proton Therapy in Breast Cancer

  • 88% less radiation dose to the heart for left-sided
    breast cancer(1,2)
  • 44% reduction in clinically significant radiation doses to
    the lung(2)
  • 90% of partial breast irradiation cases result in good to
    excellent cosmetic outcomes at 5 years(3)
  • Less than 4% serious side effects (grade 3) in locally
    advanced breast cancer(2)

NOTE: Sources available below. 

Learn More:

Thompson Proton Center

Frequently Asked Questions

What to Expect with Proton Therapy

Common Terms 




1. ClinicalTrials.gov Identifier: NCT02603341 Compare the effectiveness of proton vs. photon therapy in reducing major cardiovascular events (MCE), defined as atherosclerotic coronary heart disease or other heart disease death, myocardial infarction, coronary revascularization, or hospitalization for major cardiovascular event (heart failure, valvular disease, arrhythmia, or unstable angina).
2. Cuaron JJ, Chon B, Tsai H, et al. Early Toxicity in Patients Treated With Postoperative Proton Therapy for Locally Advanced Breast Cancer. International Journal of Radiation Oncology • Biology • Physics. 2015;Volume 92;Issue 2;284 – 291.
3. Bush D, Do S, et. al. Partial Breast Radiation Therapy With Proton Beam: 5 Year Results With Cosmetic Outcomes International Journal of Radiation Oncology • Biology • Physics. 2014;Volume 90;Issue 3;501 – 505.