Breast Cancer

Proton therapy for breast cancer lowers the risk of side effects by delivering significantly less radiation to surrounding organs like the heart and lungs, compared to traditional radiation (x-ray/IMRT).

Proton Therapy for Breast Cancer Treatment

When treating breast cancer, a patient’s treatment plan will often include a combination of treatment methods, such as surgery, chemotherapy, and radiation therapy. Proton therapy is a safe and effective an alternative to traditional radiation therapy that shows remarkable advantages for the patient’s quality of life.

The precision of proton therapy allows physicians to deliver the prescribed radiation dose to the targeted area of the breast, while avoiding unnecessary radiation to healthy tissue and vital organs. This is especially important for patients with left-sided breast cancer, where the cancer is closer to the heart and lungs. Proton therapy minimizes damage to those vital organs and lowers the risk of side effects during and after treatment.


Breast cancer is a malignant tumor that originates from tissues of the breast. The breast cancer tumor usually occurs in the lobules and ducts of the breast, which are used in the production and delivery of breast milk.

Breast cancer is the second leading cause of cancer death, surpassed only by lung cancer. It is the most common cancer among women, aside from skin cancer. Men are also susceptible to breast cancer, although the disease is rare among males.


Symptoms of breast cancer can vary. Early breast cancer usually does not cause pain and may have no symptoms at all. Some breast cancers never cause symptoms or other indications of a problem. For patients that do experience symptoms, the most common include:

  • A lump or mass in or near the breast
  • Enlarged lymph nodes in the armpit
  • Change in breast size, shape, skin texture, or color
  • Skin redness
  • Nipple discharge, erosion, inversion, or tenderness
  • Dimpling or puckering
  • Scaliness in touch


Physicians may perform several tests and procedures in the diagnosis of breast cancer:

  • Breast exam: A doctor examines both breasts to feel for any lumps or abnormalities.
  • Mammogram: An x-ray of the breast is used to identify a breast lump.
  • Breast ultrasound: Sound waves are used to produce images of structures deep within the body. Breast ultrasounds show whether the lump is solid or fluid-filled.
  • Breast biopsy: A biopsy is used to remove a sample of breast cells to determine whether or not the cells are cancerous.
  • Breast MRI: Magnetic and radio waves are used to produce images of the breast. An MRI helps better identify the breast lump or evaluate an abnormal change on a mammogram.
  • Sentinel lymph node biopsy: A procedure in which the sentinel lymph node is removed and examined under a microscope to determine whether cancer cells are present. It is used to see if the cancer has spread to areas beyond the breast.


Proton therapy is not a substitute for chemotherapy or surgery. Rather, it is an alternative to traditional radiation therapy. After surgery, a breast cancer patient is often prescribed radiation therapy.

The penetration depth of traditional x-ray radiation is difficult to control, which means it will continue beyond the tumor and expose more healthy tissue to unnecessary radiation. This can be especially worrisome for patients with left-sided breast cancer, because the cancer is closer to the heart. In fact, recent studies show a link between left-sided breast cancer x-ray treatments with an increased risk of heart disease.1

Proton therapy is a more precise form of radiation that can be controlled to stop at a very specific target. Clinical studies show that proton therapy for breast cancer results in an average of 88% less radiation to the heart and 44% less radiation to the treatment-side lung, compared to traditional x-ray therapies.2


Breast cancer patients may benefit from proton therapy if any of the following are true:

  • Patient has stage I-III breast cancer, especially if the cancer is located on the left side of the body
  • Lymph node irradiation is part of the treatment plan
  • Patient will also be receiving chemotherapy
  • Patient has preexisting vascular disorders, cardiac disease, lung disease, or increased risk of developing a secondary malignancy
  • Patient has unfavorable anatomy that places healthy organs at elevated risk of radiation exposure

In addition to the clinically-proven reduction in radiation exposure, proton therapy for breast cancer treatment offers a number of compelling quality-of-life benefits:

  • Treatment is non-invasive and painless
  • Proton therapy is effective for treating early stage breast cancer3
  • Treatment offers faster recovery time with lower risk of side effects
  • Causes less cosmetic damage compared to traditional radiation4
  • Treatment is provided in an outpatient setting
  • Proton therapy has little to no impact on a patient’s energy level

Clinical Benefits of Proton Therapy for Breast Cancer Treatment

Reduced risk of cardiac side effects 5,6
of Proton Therapy cases result in good to excellent cosmetic results for partial breast radiation patients at 5 years 4
Patient Satisfaction Rating

88% less radiation dose to the heart for left sided breast cancer.2,6

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.4

Well tolerated – Less than 4% serious side effects (grade 3) in locally advanced breast cancer.2

Nashville, TN

Telehealth now available. Speak to a physician from the safety of your own home. For information or to schedule a consultation, contact us to speak with a Cancer Care Expert.

Knoxville, TN

Telehealth now available. Speak to a physician from the safety of your own home. For information or to schedule a consultation, contact us to speak with a Cancer Care Expert.

Sources and Studies

  1. Darby S, et al. Risk of Ischemic Heart Disease in Women after Radiotherapy for Breast Cancer. N Engl J Med 368;11. Read More
  2. Early Toxicity in Patients Treated With Postoperative Proton Therapy for Locally Advanced Breast Cancer. Read More
  3. Phase II Study of Proton Beam Radiation Therapy for Patients with Breast Cancer Requiring Nodal Irradiation. Journal of Medical Oncology Read More
  4. Partial Breast Radiation Therapy With Proton Beam: 5-Year Results With Cosmetic Outcomes. Read More
  5. Taylor CW et al. Exposure of the Heart in Breast Cancer Radiation Therapy: A Systematic Review of Heart Doses Published During 2003 to 2013. Int J Radiat Oncol Biol Phys. 2015 Nov 15;93(4):845-53. PMID: 26530753 Read More
  6. Lin LL et al. Proton beam versus photon beam dose to the heart and left anterior descending artery for left-sided breast cancer. Acta Oncol. 2015 Jul;54(7):1032-9. PMID:25789715 Read More
  7. Phase III randomized trial proton vs photon therapy for patients with non-metastatic breast cancer receiving comprehensive nodal radiation: A radiotherapy comparative effectiveness (RADCOMP) Consortium trial. Read More
  8. MacDonald S, Specht M, Isakoff S, et al. Prospective pilot study of proton radiation therapy for invasive carcinoma of the breast following mastectomy in patients with unfavorable anatomy – first reported clinical experience. Int J Radiat Oncol. 2012;84(Suppl 3):S113-S114. Abstract 281
  9. Moon SH, Shin KH, Kim TH, et al. Dosimetric comparison of four different external beam partial breast irradiation techniques: three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, helical tomotherapy, and proton beam therapy. Radiother Oncol. 2009;90:66-73.