For patients with breast cancer, your doctor may recommend considering radiation therapy as part of your treatment. Radiation therapy may be needed if you have undergone a mastectomy, if the tumor is large, or if the cancer has metastasized to lymph nodes or other parts of the body. Radiation therapy also helps prevent cancer recurrence after breast-conserving surgery.
The most common form of radiation therapy for breast cancer is external radiation therapy, one of which is proton therapy, which can target only the tumor without damaging surrounding healthy tissue; another name for this is intensity modulated proton therapy (IMPT).
Proton therapy can be used for cancers near vulnerable or critical areas of the body if the radiation can cover them. The breast is one area that is very close to critical organs like the heart and lungs. Doctors believe that proton therapy can help patients get better results while reducing the risk of radiation damage to these vital organs.
How is proton therapy different?
Proton therapy destroys tumors in the same way as traditional cancer radiation therapy, by destroying the DNA inside the cancer cells.
Standard radiation therapy (X-rays) uses high-energy light waves called photons to do this. When X-rays pass through a patient’s body, they radiate the entire body, and they do not stop after they have attacked the tumor; they continue on through the treated area, which can cause damage to healthy tissue.
Proton therapy uses beams of electrically charged particles called protons to kill cancer cells. Protons deliver a large amount of strike energy directly to the tumor and do not cross the treatment area, which means that tissue near the tumor is much less likely to be damaged by the radiation.
What are the benefits of proton therapy for breast cancer?
Patients with left-sided breast cancer who receive conventional x-ray therapy (or radiation therapy) are more likely to develop ischemic heart disease, a serious heart problem caused by narrowing of the arteries. This risk begins about 5 years after treatment and lasts for at least 20 years. The higher the dose of radiation therapy, the higher the risk for patients.
Proton therapy helps avoid this risk as well as other complications, and other benefits include:
- Painless.
- Non-invasive (no surgery or incisions required).
- Can be used in combination with other anti-cancer treatments.
- Can be used in patients with breast implants.
Proton therapy has almost no side effects, and patients seem to tolerate this type of radiation therapy better than standard radiation therapy.
What types of breast cancer can proton therapy be used for?
Patients can talk to their doctor about whether proton therapy is available for them, depending on their type and stage of breast cancer.
Proton therapy may be available for those who meet the following criteria:
- Stage I, II, or III breast cancer.
- Breast cancer that has metastasized to the chest wall, skin, or axillary lymph nodes but not to other organs (locally advanced breast cancer).
- Breast cancer cells found in the lymph nodes (lymph node positive breast cancer).
Studies exploring the benefits of proton therapy for breast cancer are ongoing, and some providers are recruiting patients to participate in the studies.
How is it treated?
Radiologists and clinicians will work together to develop a proton treatment plan for patients.
A few days before the first treatment, the patient will receive a mock treatment where the radiation team will mark the treatment site on the patient’s body so they know where to aim the beam. They may use a permanent marker to draw lines, circles, or perhaps a small spot-like pattern.
During treatment, patients need to lie still to allow the right amount of radiation to reach the tumor. If moved or shifted, the rays may miss the target area. There may be a frame or mold to help keep the patient in place. The treatment may last up to 30 minutes.
Patients may receive this treatment several times in about 6 weeks.