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Fight Breast Cancer
with Laser-like Precision

Proton Therapy for Breast Cancer

California Protons’ intensity-modulated pencil beam scanning technology is a highly precise form of cancer radiation treatment that enables our doctors to selectively target breast tumors with high-dose radiation within this intricate area.

Compared with older passive-scattering proton therapy treatment, our pencil beam scanning technology precisely delivers proton radiation treatment for breast cancer within 2 millimeters and with the utmost care. We attack tumors layer by layer and minimize harmful exposure to surrounding healthy tissue and organs. This is important for breast cancer patients who may face the risk of secondary cancers, lung injuries and major cardiac events later in life due to previous radiation exposure. The reduction of radiation-related toxicity also increases the likelihood that patients can complete treatment with fewer interruptions or delays.

Breast Cancer
Treatment Details

What We Treat

  • Early stage breast cancer
  • Locally advanced breast cancer (Stage II and III)
  • Ductal carcinoma in-situ
  • Triple-negative breast cancer
  • Recurrent cancer

What We Do

  • Target the tumor only
  • Protect your heart, lungs and spinal cord
  • Maintain your quality of life during treatment
  • Reduce side effects of radiation therapy, including risk of cardiac events, lung cancer and pneumonitis
  • Lower the risk of secondary cancer due to radiation

A test of treatment plans for women with left-sided breast cancer undergoing breast-conserving therapy found that compared to X-ray radiation, proton therapy resulted in:

Reduced radiation dose to the lung1
Reduced radiation to the other breast1
Reduced radiation dose to the heart1

Benefits of Proton Therapy for Breast Cancer

  • Our pencil beam scanning technology precisely controls protons to place the Bragg peak—the point at which they deposit their maximum energy—directly in the tumor. This allows us to treat more complex tumor shapes and vary the dose within the tumor.
  • Advanced proton therapy allows doctors to more selectively deliver high-dose radiation to cancerous breast tumors and tissues, and reduce the dose to surrounding healthy tissues and critical organs. In some cases, this has been shown to deliver higher cure rates than X-ray radiation treatment even in some of the most challenging situations.
  • Studies have found that proton therapy provides better coverage of the lymph nodes, while substantially reducing average radiation doses to the heart and lungs. This ultimately results in a reduced risk of cardiac events, lung cancer and pneumonitis.
  • Partial breast irradiation (PBI) with proton therapy provides a more even distribution of radiation and reduces exposure to healthy breast tissue, heart and lungs compared with photon and X-ray PBI techniques. It has also been associated with reduced toxicity and many excellent outcomes.
  • Unlike with older technology, the treatment plan can be loaded into the computer and completed within a matter of minutes. Treatments are also noninvasive and convenient so patients can get back to their daily activities quicker.

Proton Therapy
Right for You?


Depending on the stage of breast cancer, combined treatments of mastectomy or lumpectomy surgery, chemotherapy and radiation may be needed for some breast tumors. Treatment options also are affected by the type of breast cancer, age, overall health and personal preferences.

Breast cancer is relatively small at this stage and has not spread to the lymph nodes at all, or has spread to only a very small area in the sentinel lymph node. While surgery is the most common treatment, radiation therapy for stage I breast cancer is often recommended after surgery to reduce the risk of cancer spreading or returning.

These breast cancers are larger than stage I cancers and/or have spread to a few lymph nodes. While surgery is the most common treatment, radiation therapy is often recommended after surgery to reduce the risk of cancer spreading or returning.

Tumors at this stage are larger than 5 cm, or the cancer is growing into nearby skin or muscle tissue or has spread to many nearby lymph nodes. While surgery is the most common treatment, radiation therapy is often recommended after breast cancer surgery to reduce the risk of cancer spreading or returning.

At this stage, cancer has spread beyond the breast and nearby lymph nodes to other parts of the body. Drug therapy such as chemotherapy and/or hormone therapy are the main treatments recommended for women with stage IV breast cancer. At this stage, proton radiation treatment may be used to shrink tumors or control pain.

Treatment for
Recurrent Cancer

Proton therapy is often the best way to treat recurrent tumors in areas that have previously been treated with radiation therapy.

Treating previously irradiated areas can be challenging. The healthy tissues around the recurrent tumor do not fully “forget” the previous radiation dose, and any added dose continues to increase the risk of normal tissue injury. Proton beam therapy may enable doctors to better concentrate the dose to the target and limit it elsewhere, allowing re-treatment with radiation in select patients.

Treatment Outcomes &
Long-Term Effects

Proton therapy treatment at California Protons Cancer Therapy Center in San Diego may offer similar outcomes to standard X-ray radiation, while reducing long-term and potentially life-threatening side effects such as heart attacks due to radiation damage to the heart. It also offers the possibility of lower chances for secondary cancers later in life due to the reduced radiation exposure to your surrounding healthy tissues and organs.

However, all cancer treatments have advantages and disadvantages. Be sure to discuss all of the potential risks, as well as treatment options, with your oncologist.

Marti Shelton
I wanted to live a long life and didn’t want to risk having a heart attack or heart damage, so I chose proton therapy. After my consultation with Dr. Chang, I just knew that California Protons is where I wanted to be. He spent so much time with me and I felt very confident in his ability.
Marti Shelton
Breast Cancer Patient

About Proton Therapy

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